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REVISION REQUEST 4165

Several foundational documents guide MoDOT’s TSMO program:

• TSMO Program and Action Plan – outlines MoDOT’s statewide TSMO vision, goals, and implementation strategies.
• TSMO Informational Memoranda – provides background, technical details, and
• TSMO Benefit-Cost Reference Memo – provides the benefit-cost information on TSMO applications that are critical to MoDOT’s TSMO program and future work.
• Work Zone Management Guidebook – provides a comprehensive set of tools and strategies for work zone management and describes “advanced work zone” practices, guidance, and resources
• Connected and Automated Vehicle Action Plan – articulates MoDOT’s mission, vision, strengths, and strategic focus areas for leveraging CV/AV technologies, and lays out actions across institutional capability-building, outreach and education, and partnership development to support safe, efficient deployment.

Transportation Systems Management and Operations (TSMO) consists of operational strategies and systems that cost-effectively optimize the safety, reliability, efficiency, and capacity of the transportation system. TSMO emphasizes maximizing the performance of the existing system through proactive management and operational improvements.

909.1 Introduction to TSMO

909.1.1 Overview of TSMO Strategies

TSMO strategies are the day-to-day operational actions MoDOT uses to actively manage the transportation system and address the primary causes of congestion without relying solely on capacity expansion.

Congestion generally falls into two categories:

• Non-recurring delays arise from unplanned or irregular events such as incidents, disasters, weather, work zones, and special events. These disruptions are inherently unpredictable, vary in severity and duration, and often require dynamic traffic management and interagency coordination to reduce their impact.
• Recurring delays occur regularly at specific locations, most often during peak traffic periods. This type of congestion is usually the result of demand exceeding the capacity of the existing system. Transportation agencies do not have the resources to construct enough highway capacity to eliminate all recurring congestion. Instead, TSMO strategies provide more cost-effective ways to manage demand and improve flow.

By addressing both types of congestion, TSMO supports MoDOT’s mission of moving Missourians safely and reliably while making the best use of available resources. These strategies are organized based on whether they address non-recurring delays or recurring delays, as described below.

909.2 Non-Congested Route (Non-Recurring Delays) – These strategies focus on managing temporary (whether short-term or long-term) capacity reductions caused by irregular or time-limited events that disrupt normal traffic conditions, with the goal of restoring mobility and safety efficiently and consistently.

• 909.2.1 Traffic Incident Management: Coordinates detection, response, and clearance across multiple agencies to minimize secondary crashes and return roadways to normal operation quickly.
• 909.2.2 Transportation Operations for Emergency Incidents or Disasters: Supports system readiness and coordinated response during natural or human-caused disasters through planning, communication, and multimodal evacuation procedures.
• 909.2.3 Road Weather Management: Integrates environmental monitoring, data-driven decision support, and targeted maintenance to mitigate the effects of adverse weather on safety and mobility.
• 909.2.4 Work Zone Traffic Management: Applies smart work zone technologies and comprehensive traffic management plans to maintain safe and reliable travel through construction and maintenance areas.
• 909.2.5 Planned Special Event Management: Coordinates transportation, enforcement, and communication activities for scheduled events to maintain efficient system operations and traveler safety.

909.3 Congested Route (Recurring Delays) – These strategies address predictable and routine congestion caused by daily travel demand and capacity constraints on specific facilities or corridors, emphasizing active traffic management, system integration, and multimodal coordination.

• 909.3.1 Freeway Operations and Management: Improves freeway performance through corridor-level monitoring, adaptive control, and coordinated operations to enhance safety and travel-time reliability.
• 909.3.2 Arterial Operations and Management: Optimizes signal timing, intersection design, and corridor coordination to improve mobility and safety on surface streets.
• 909.3.3 Freight Operation: Enhances the efficiency and safety of freight movement through improved access, parking management, and technology-based monitoring along key freight corridors.
• 909.3.4 Vulnerable Road Users: Improves safety, accessibility, and comfort for VRUs through targeted infrastructure, operational strategies, and multimodal coordination.
• 909.3.5 Transit Operation: Strengthens transit reliability and accessibility through operational strategies such as priority treatments, multimodal hubs, and corridor management.

909.1.2 Relationship with Other Programs

TSMO is not a standalone initiative—it complements and enhances MoDOT’s other programs:

• Safety Programs: TSMO contributes to MoDOT’s safety goals, as outlined in the Strategic Highway Safety Plan and the SAFER Program (see EPG 907.9 Safety Assessment For Every Roadway (SAFER)), by reducing secondary crashes, improving work zone management, and advancing road weather management capabilities.
• Asset Management: Proper maintenance of TSMO strategies and supporting systems can improve how facilities operate, reduce incidents that accelerate wear, and extend the life of infrastructure investments.
• Planning and Design: TSMO principles should be incorporated early in the planning and design process so that operational strategies are built into projects from the start.
• Maintenance: Maintenance activities can be coordinated with TSMO tools such as smart work zones and ITS devices to reduce traffic disruptions.
• Traveler Information: TSMO strengthens customer service by providing real-time, accurate, and actionable information to the traveling public.

In practice, TSMO serves as the operational thread that connects safety, planning, design, maintenance, and customer service into a unified system-management approach.

909.0.3 Roles and Contributions for TSMO Implementation

This guide is designed to provide MoDOT staff and partners with a clear, practical reference for TSMO strategies. Table 909.1.3 highlights the typical roles and potential TSMO contributions of different staff in implementing and supporting TSMO strategies, as applicable based on project context, needs, and available resources. These contributions are intended to guide coordination and consideration of TSMO strategies and may vary depending on the specific application.

Table 909.1.3. Typical Roles and Potential Contributions for TSMO Implementation

Role	Potential TSMO Contribution
Transportation Management Center (TMC) Operator	Monitor traffic conditions, manage information systems, and coordinate incident response and traveler communication to maintain safe and efficient roadway operations.
Emergency Response Operator	Provide on-scene incident management, motorist assistance, and roadway clearance to restore normal traffic flow and enhance safety during disruptions.
Maintenance Technician	Implement maintenance related TSMO strategies; provide feedback and effort for continual improvement of these strategies and tools.
Traffic Operations Engineer	Implement traffic operations related TSMO strategies; provide feedback and effort for continual improvement of these strategies and tools.
Transportation Planner	Incorporate TSMO and other traditional transportation improvement strategies into planning efforts, as appropriate.
Design Staff	Consider TSMO as a key element of design, where applicable, either as a direct improvement for the specific application or as an opportunity for the continuation of existing TSMO strategies.
Construction Inspector	Coordinate with appropriate personnel when modifying design elements or inspecting TSMO related infrastructure.
Work Zone Specialists	Oversee temporary traffic control in construction zones; review and manage Transportation Management Plans (TMPs), ensure proper setup and quality of traffic control devices, assess risks, and provide input during planning and post-construction reviews to enhance safety and minimize disruptions.
Information Systems Manager	Provide oversight and management of field and central communications systems, computer and software, and other information systems resources.
Human Resources Specialist	Incorporate relevant related skills and experience into position descriptions where TSMO expertise is needed; assist with training programs to improve the knowledge, skills, and abilities of existing operations personnel.
Emergency Management Agencies	Support TSMO implementation by providing coordinated incident response, traffic control, emergency medical services, and roadway clearance; collaborate with MoDOT and TMC staff, when applicable, to improve incident management, responder safety, and system recovery during emergencies and planned events.

909.1.4 TSMO Implementation Framework

The TSMO Implementation Framework provides a structured approach for MoDOT to translate its mission and agency goals into actionable objectives and strategies. It supports the development of purpose-driven, measurable strategies aligned with statewide priorities. This framework serves as a bridge between MoDOT’s overarching mission and the specific strategies implemented across the TSMO program. Effective implementation of these goals relies on coordination across disciplines, integration throughout project phases, and collaboration with internal and external partners.

Table 909.1.4.1 identifies the core programmatic elements, MoDOT’s goals and associated objectives, that guide how TSMO is planned, implemented, and evaluated.

Table 909.1.4.1 Programmatic Element

Goal	Objective
Safety	Reduce crash frequency and severity through proactive deployment of TSMO strategies (e.g., incident management, work zone safety, network operations).
Reliability	Support predictable and consistent travel times across the system by proactively managing congestion and incidents.
Efficiency	Operate MoDOT’s existing system efficiently and effectively through the application of TSMO strategies, as appropriate, to improve performance and inform decisions regarding potential capacity expansion.
Customer Service	Support timely, accurate, and useful traveler information that enables informed decision-making.

Table 909.1.4.2 links MoDOT’s mission to measurable outcomes and example TSMO strategies, demonstrating how operations initiatives directly support statewide goals.

Table 909.1.4.2. Linking MoDOT Mission to Outcomes and Example TSMO Strategies

Mission	High-Level Outcome	Example TSMO Strategy
Improving safety (Moving Missourians safely)	Reduction in crashes, fatalities, and serious injuries; safer travel for all users	• 909.2.1 Traffic Incident Management • 909.2.3 Road Weather Management • 909.2.4 Work Zone Traffic Management • 909.3.1 Freeway Operations and Management • 909.3.2 Arterial Operations and Management
Providing high-value, impactful solutions (Delivering efficient and innovative transportation projects; asset management)	Cost-effective improvements that maximize existing infrastructure and delay costly expansions	• 909.3.1 Freeway Operations and Management • 909.3.2 Arterial Operations and Management • 909.3.3 Freight Operation • 909.3.4 Vulnerable Road Users
Improving reliability and mobility (Operating a reliable transportation system; Building a prosperous economy for all Missourians)	Predictable travel times and improved system performance for people and freight	• 909.2.1 Traffic Incident Management • 909.2.4 Work Zone Traffic Management • 909.2.5 Planned Special Event Management • 909.3.1 Freeway Operations and Management • 909.3.5 Transit Operation
Providing useful and timely traveler information (Providing outstanding customer service)	Informed travel decisions by the public, increased user satisfaction	• 909.2.2 Transportation Operations for Emergency Incidents or Disasters • 909.2.3 Road Weather Management

909.1.5 Performance Metrics

Performance metrics provide the foundation for evaluating how TSMO strategies contribute to the safety, reliability, efficiency, and customer experience of Missouri’s transportation system. MoDOT currently tracks performance through a combination of federal performance measures and internal performance management tools (e.g. Tracker: Measures of Departmental Performance). The following tables present example performance measures that may be used to assess the effectiveness of TSMO strategies related to both non-recurring delays (Table 909.1.5.1) and recurring delays (Table 909.1.5.2).

These measures are not intended to represent required or standalone reporting metrics, but rather a menu of potential measures that can support analysis, planning, and evaluation efforts, as appropriate to the specific application, study type, or operational need. When applied, these metrics can help users identify opportunities for improvement and support data-driven decision-making.

Table 909.1.5.1 Linking MoDOT TSMO Strategies for Non-Recurring Delays to Performance Metrics

Strategy	Goals	Example Performance Metric
909.2.1 Traffic Incident Management	Enhance the safety of traveling public and incident responders	• Number of secondary crashes per incident • Severity (fatalities/serious injuries) of secondary crashes • Percent of incidents with secondary crashes recorded • Number of responders struck-by crashes • Severity of responder-involved crashes • Percent of incidents with responder crash data recorded
	Enhance reliability and efficiency of Missouri’s transportation system	• Average roadway clearance time • Average incident clearance time • Percent of incidents meeting clearance time targets
	Strengthen coordination, communication, and collaboration between MoDOT and TIM partners	• Number of formalized agreements signed • Number of multi-agency TIM meetings held annually • Number of TIM trainings held annually • Partner participation rate in meetings/exercises
	Establish TIM policies, procedures, and protocols within MoDOT	• Number of formal TIM policies/protocols adopted • Percent of TIM coordinator positions filled and active
909.2.2 Transportation Operations for Emergency Incidents or Disasters	Enhance safety and responder protection during emergency incidents	• Number of emergency-related crashes • Severity (fatal/serious injury) of emergency-related crashes • Percent of emergency incidents with responder safety data recorded
	Improve reliability and speed of emergency response and system restoration	• Time to activate emergency operations • Duration of emergency lane/road closures • Percent of priority routes restored within target timeframes • Emergency communication system uptime • Average time to deploy emergency traffic control
909.2.3 Road Weather Management	Improve safety under adverse weather conditions	• Number of weather-related crashes, fatalities, and serious injuries • Crash rate per weather event
	Enhance operational readiness and timely roadway treatment	• Time to treat priority routes during storms • Percent of network treated within specific time thresholds • Materials usage efficiency (salt, brine, abrasives)
	Improve traveler information accuracy during weather events	• Traveler information system accuracy rate during storms • Number of travel information interactions (511 apps, CMS messages)
909.2.4 Work Zone Traffic Management	Enhance safety for workers and motorists in work zones	• Number and rate of work zone crashes • Number of work zone fatalities and serious injuries • Number of work zone intrusions (near-miss events)
	Improve mobility and reduce unexpected work zone delays	• Work-zone related delays • Percent of work zones meeting mobility targets (queue length, speed, travel time) • Average incident clearance time for work zone-related incidents
909.2.5 Planned Special Event Management	Ensure safe travel conditions during special events	• Number and rate of special event-related crashes • Vulnerable Road User (VRU) level of comfort/safety index near event venues
	Improve mobility and minimize event-related congestion	• Travel time reliability during event periods • Vehicle and pedestrian throughput at key access points • Percent of events meeting planned operational performance targets

Table 909.1.5.2 Linking MoDOT TSMO Strategies for Recurring Delays to Performance Metrics

Strategy	Goals	Example Performance Metric
909.3.1 Freeway Operations and Management	Support safety on managed freeway facilities	• Number and rate of crashes on freeway segments • Number of secondary crashes
	Improve travel reliability on freeway corridors	• Travel time reliability index • Planning time index
	Enhance operational efficiency on freeway corridors	• Average travel speed and delay • Vehicle and truck throughput • Number of recurring congestion hotspots mitigated
909.3.2 Arterial Operations and Management	Enhance safety at signalized intersections and arterials	• Crash frequency and severity at signalized intersections • Pedestrian and bicycle crash rate
	Improve efficiency of arterial traffic flow	• Arterial travel time and delay • Signal progression quality (arrival on green, bandwidth) • Number of mitigated congestion hotspots
	Enhance reliability of multimodal arterial operations	• Transit signal delay at signals (if applicable) • Pedestrian crossing delay
909.3.3 Freight Operation	Improve efficiency on key freight corridors	• Truck delay at bottlenecks • Freight throughput (corridor or intermodal facility)
	Enhance reliability of freight travel	• Truck travel time reliability index • Number of freight-related congestion hotspots mitigated
909.3.4 Vulnerable Road Users	Enhance safety and comfort for Vulnerable Road Users (VRUs)	• Number and rate of VRU crashes • VRU level of comfort/safety index
	Improve connectivity for walking and bicycling	• Miles of connected pedestrian/bicycle facilities • Percent of network meeting connectivity standards
	Support sustainable, multimodal travel options	• Share of trips completed using active modes
909.3.5 Transit Operation	Enhance mobility of transit users	• Passenger throughput per route or corridor • Average transit travel time
	Improve transit reliability and on-time performance	• Percent of on-time arrivals • Transit travel time reliability (travel adherence)
	Improve customer experience and multimodal access	• Customer satisfaction survey results • Pedestrian access quality (stop accessibility index)

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909.2.1 Traffic Incident Management

Traffic Incident Management (TIM) can help reduce the impact of roadway incidents by coordinating detection, response, and clearance activities among transportation, law enforcement, fire, EMS, towing, and other partners.

While crashes, disabled vehicles, and cargo spills are the most common focus of TIM programs, there are a broader set of disruptions that can also be monitored including:

• Debris in the roadway
• Grass fires
• Lane-blocking emergency vehicles
• Vehicle fires
• Heavy congestion

By incorporating this broader incident set, TIM strategies ensure operators and responders are prepared for a wide range of events that may impact traveler safety and network performance. The following sections outline strategies for TIM.

Users:

• TMC Operators → Detect and coordinate response (909.2.1.3 Components), disseminate traveler information (909.2.1.1 Traffic Incident Management Plans).
• Maintenance Technicians → Assist with clearance and roadway restoration (909.2.1.3 Components).
• Emergency Management Agencies → Critical frontline responders (909.2.1.2 Stakeholders).

909.2.1.1 Traffic Incident Management Plans

Traffic incidents occur without warning at any time and location on the highway system. On all segments of the interstate and freeway highway system, TIM plans should be developed in coordination with law enforcement and local responders to:

• Reduce response and clearance times.
• Develop alternate plans for handling affected traffic.
• Communicate and coordinate between first responders.
• Communicate traffic impacts to motorists.

Reference EPG 948 Incident Response Plan and Emergency Response Management for additional information.

909.2.1.2 Stakeholders

Effective TIM depends on collaboration among a wide range of partners. Law enforcement, fire/rescue, EMS, and towing operators provide immediate on-scene response, while MoDOT personnel and TMCs deliver critical support through detection, traffic control, and traveler information. Each stakeholder brings unique capabilities, and coordinated multi-agency response supports faster clearance, safer conditions for responders, and more reliable outcomes for the traveling public.

909.2.1.3 Components

The core components of TIM—detection, verification, response, clearance, and recovery—create a structured framework for managing roadway incidents. Detection and verification confirm the incident type and location; coordinated response mobilizes the appropriate agencies; clearance restores traffic lanes and removes hazards; and recovery ensures the roadway is returned to normal operation. Addressing each component systematically reduces incident duration and enhances both safety and reliability.

909.2.2 Transportation Operations for Emergency Incidents or Disasters

Emergency operations support safe and effective evacuation and mobility during disasters such as floods, tornadoes, earthquakes, or other emergencies. The following sections outline strategies for emergency operations during disasters.

Users:

• Emergency Management Agencies → Coordinate disaster response (909.2.2.1 Frameworks and Coordination).
• Transportation Planners → Prepare evacuation plans (909.2.2.2 Preparedness and Planning).
• Traffic Operations Engineers → Manage ingress and egress traffic flow (909.2.2.3 Operational Strategies During Disasters).
• TMC Operators → Monitor evacuation routes and push real-time traveler information (909.2.2.3 Operational Strategies During Disasters).

909.2.2.1 Frameworks and Coordination

MoDOT’s emergency transportation operations should align with the National Incident Management System (NIMS) and the Incident Command System (ICS). These frameworks establish the standard structure, terminology, and coordination processes for incident and disaster response at the local, state, and federal levels.

National Incident Management System (NIMS):

• Provides a nationwide approach for incident management and coordination.
• Provides emergency transportation operations guidance for interoperable collaboration with law enforcement, fire, EMS, emergency management, and federal partners.
• Establishes common terminology, communication protocols, and resource management procedures to support multi-agency operations.

Incident Command System (ICS):

• Serves as the on-scene management structure for all types of incidents.
• Defines clear roles, responsibilities, and reporting relationships across agencies.
• Provides guidance on unified command structures, filling roles such as transportation branch directors, field observers, or technical specialists.
• Provides flexibility to scale operations for localized or statewide events.

For detailed response information, please contact MoDOT’s Safety and Emergency Management.

909.2.2.2 Preparedness and Planning

• Develop and exercise evacuation and emergency operations plans.
• Use simulation and scenario testing to identify gaps and strengthen interagency protocols.
• Establish pre-designated staging areas for resource allocation, evacuation support, and vehicle marshaling.

909.2.2.3 Operational Strategies During Disasters

• Traffic Management: Complete rapid damage assessment and plan and publish routes for ingress and egress to the impacted area.
• Multimodal Evacuations: Utilize buses, school buses, and regional transit providers to assist in large-scale evacuations.
• Route Monitoring: Employ field observations, cameras, and sensors to track evacuation route conditions in real time.
• Public Information: Provide timely traveler information, evacuation messaging, and updates in coordination with media partners.

909.2.3 Road Weather Management

Road Weather Management strategies improve mobility, reliability, and safety during weather events through strategies such as targeted traveler information, warnings, and operational interventions. The following sections outline strategies for road weather management.

Users:

• TMC Operators → Operate dynamic message signs and push alerts (909.2.3.1 Road Weather Warnings/Alerts and Dynamic Message Signs; 909.2.3.2 Road Weather Information Systems).
• Maintenance Technicians → Respond to weather conditions, deploy treatment (909.2.3.2 Road Weather Information Systems).
• Traffic Operations Engineers → Integrate road weather information systems data (909.2.3.1 Road Weather Warnings/Alerts and Dynamic Message Signs; 909.2.3.2 Road Weather Information Systems).

909.2.3.1 Road Weather Warnings/Alerts and Dynamic Message Signs

Used to display real-time information to warn motorists of roadway incidents, construction or congestion ahead that could pose a hazard or cause delays.

Procedures for Dynamic Message Signs are outlined in EPG 910.3 Dynamic Message Signs (DMS).

909.2.3.2 Road Weather Information Systems

Road Weather Information Systems (RWIS) provide real-time data on weather and roadway conditions to support transportation system operations and maintenance activities. These systems collect information such as air and pavement temperatures, precipitation, visibility, and surface conditions to help inform operational decisions. Data may be collected through field sensors, third-party weather service providers, or a combination of both, depending on system needs and available resources.

909.2.4 Work Zone Traffic Management

Work zone strategies reduce risk to workers and travelers while minimizing delays during construction and maintenance activities. These strategies apply to both short-term and long-term work zones, recognizing that every project, regardless of duration, can significantly affect roadway operations and safety. The following sections outline strategies for work zone traffic management.

Users:

• Design Staff → Incorporate TMP and ITS strategies into project design, when practical (909.2.4.1 Traffic Management Plan; 909.2.4.4 Use of Intelligent Transportation Systems).
• Work Zone Specialists → Review and manage TMPs, oversee traffic control device setup, and ensure compliance with MoDOT standards (909.2.4.1 Traffic Management Plan; 909.2.4.2 Traffic Incident Management Plan).
• Construction Inspectors → Enforce work zone traffic control measures (909.2.4.2 Traffic Incident Management Plan).
• Traffic Operations Engineers → Oversee ITS integration and system strategies (909.2.4.3 Smart Work Zones; 909.2.4.4 Use of Intelligent Transportation Systems).
• TMC Operators → Monitor work zones and disseminate real-time traveler information (909.2.4.4 Use of Intelligent Transportation Systems).

909.2.4.1 Traffic Management Plan

The Transportation Management Plan (TMP) consists of strategies to manage the work zone impacts of a project. Each TMP is tailored to the unique conditions of a project and typically incorporates three coordinated elements: Traffic Control Plan (TCP), Traffic Operations (TO), and Public Information and Outreach (PIO).

As an initial step, a project design should be selected to eliminate or minimize additional delays and traffic queueing during construction. EPG 616.19 Work Zone Capacity, Queue and Travel Delay provides tools to assess the traffic impact of the proposed project design(s).

For additional detail on the required elements, development process, and documentation standards for TMPs, reference EPG 616.20.9 Work Zone Transportation Management Plan. For additional information on developing Work Zone Traffic Management JSPs for use in core team meetings, reference EPG 616.20.7 Significant Projects.

909.2.4.2 Traffic Incident Management Plan

When traffic incidents occur within a work zone, it is important to clear the incident and restore traffic as quickly as possible. To aid in this effort, a project-based traffic incident management (TIM) plan should be developed for all significant projects on interstate and freeways.

Reference EPG 909.2.1.1 Traffic Incident Management (TIM) Plans for additional information.

909.2.4.3 Smart Work Zones

Once a project design has been determined, the MoDOT Work Zone Impact Analysis Spreadsheet will assist in determining which smart work zones strategies should be included in the project to provide information and warnings to motorists to improve work zone safety and traffic mobility.

Additionally, the Work Zone Management Guidebook provides information about tools and strategies for work zone management that will maximize safety and minimize the impacts to traffic. The Work Zone Management Guidebook Presentation provides additional information about the guidebook.

The nonstandard Work Zone Intelligent Transportation System special provision is available for reference in EPG 616.19.6.3 Smart Work Zone (SWZ) Strategy Selection. Additional information can also be found in EPG 616.19 Work Zone Capacity, Queue and Travel Delay and EPG 616.20 Work Zone Safety and Mobility Policy.

909.2.4.4 Use of Intelligent Transportation Systems

Intelligent Transportation Systems (ITS) devices (cameras, sensors, communication systems) provide detection and real-time monitoring of work zones.

Procedures for ITS devices are outlined in EPG 910 Intelligent Transportation Systems.

909.1.5 Planned Special Event Management

Special event management strategies ensure safe and efficient mobility during large gatherings, sporting events, and other planned activities. The following sections outline key strategies for planned special event management.

Users:

• Transportation Planners → Develop TMPs for special events and coordinate agencies (909.1.5.1 Pre-Event Planning; 909.1.5.4 Post-Event Evaluation).
• Traffic Operations Engineers → Design strategies for traffic flow and multimodal support (909.1.5.2 Implementation).
• TMC Operators → Manage day-of-event operations and traveler communications (909.1.5.3 Day-of-Event Operations).
• Emergency Management Agencies → Manage access, safety, and enforcement (909.1.5.2 Implementation).

909.1.5.1 Pre-Event Planning

• Develop Transportation Management Plans (TMPs) with input from MoDOT, local agencies, law enforcement, transit providers, and event organizers.
• Identify needs for Emergency Operations Center (EOC) and Joint Operations Center (JOC) activation, staffing augmentation, and resource staging for high-profile or large-scale events (e.g., sporting events, major concerts, parades, funerals, festivals, eclipse, political events).
• Plan for multimodal access (transit, walking, biking) and freight restrictions, where applicable.

909.1.5.2 Implementation

• Deploy traffic control devices, signage, and ITS in advance of the event.
• Coordinate with law enforcement and emergency management on enforcement zones, access control, and responder staging.
• Conduct interagency briefings to confirm roles, responsibilities, and communication protocols.

909.1.5.3 Day-of-Event Operations

• Manage traffic and crowd circulation using TMC monitoring, field staff, and real-time traveler information (dynamic message signs, push alerts, social media).
• Coordinate with EOC/JOC if activated to ensure situational awareness and resource support.
• Adjust plans dynamically to address congestion, incidents, or security needs.

909.1.5.4 Post-Event Evaluation

• Conduct after-action reviews with MoDOT staff, law enforcement, emergency management, and event organizers.
• Document lessons learned, identify gaps in staffing or coordination, and refine TMPs for future events.
• Capture performance measures such as clearance times, delay estimates, and traveler feedback.

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909.2.1 Freeway Operations and Management

Freeway operations strategies enhance safety, reduce recurring congestion, and improve travel time reliability on major corridors. The following sections outline key strategies for freeway operations and management.

Users:

• TMC Operators → Monitor and adjust dynamic controls, coordinate corridor operations, and manage incident response (909.2.1.1 Ramp Management and Control; 909.2.1.3 Dynamic Speed Limits; 909.2.1.4 Queue Warning; 909.2.1.5 Integrated Corridor Management; 909.2.1.6 Traffic Management Centers).
• Traffic Operations Engineers → Design freeway operations strategies, oversee policy-sensitive strategies, and evaluate corridor performance (909.2.1.2 Part-Time Shoulder Use; 909.2.1.5 Integrated Corridor Management; 909.2.1.6 Traffic Management Centers; 909.2.1.7 Managed Lanes).
• Information Systems Managers → Maintain ITS infrastructure, support automated detection, and ensure system integration for real-time operations (909.2.1.5 Integrated Corridor Management; 909.2.1.6 Traffic Management Centers; 909.2.1.8 Automated Incident Detection).

Policy Coordination – Any consideration or application of the following strategies in Missouri should be closely coordinated with MoDOT’s Central Office of Highway Safety and Traffic (COHST) to ensure consistency with policy, design standards, and operational oversight.

909.2.1.1 Ramp Management and Control

Ramp management and control strategies, including ramp metering and adaptive ramp management, regulate vehicle entry onto freeways to improve merging operations, reduce conflicts, and smooth overall traffic flow. This remains a dynamic application where it is implemented, with operational adjustments based on corridor conditions.

Currently, Missouri does not operate continuous ramp metering systems. Instead, ramp meters are activated dynamically based on real-time traffic conditions when metrics (such as speed, volume, and/or density) exceed predefined thresholds.

909.2.1.2 Part-Time Shoulder Use (Hard Shoulder Running)

Part-time shoulder use, also known as hard shoulder running, allows roadway shoulders to serve as temporary travel lanes during peak periods, incidents, or emergencies. Applications may be designed for all vehicles or limited to transit operations.

This strategy is increasingly being implemented by peer agencies across the country, particularly in corridors with limited right-of-way or peak-period capacity needs. While Missouri does not currently have any active applications of part-time shoulder use, the concept may present opportunities in select corridors - especially where traditional widening is not feasible and where shoulders are constructed to full-depth pavement standards.

909.2.1.3 Dynamic Speed Limits

Dynamic speed limits adjust posted speed limits in real time based on conditions such as traffic flow, weather, or incidents. This approach has been applied by several peer agencies to improve safety, smooth traffic flow, and reduce crash risk.

In Missouri, there are no permanent applications of dynamic speed limits in routine freeway operations. However, the strategy may hold value in targeted, temporary contexts—particularly in work zones where changing conditions require more flexible speed management.

909.2.1.4 Queue Warning

Queue warning systems are designed to alert motorists of slow or stopped traffic ahead, reducing the likelihood of sudden braking and rear-end collisions in congested conditions. These systems typically consist of roadside sensors and Changeable Message Signs (CMS) that detect traffic slowdowns and display real-time warnings to approaching drivers. When sensors identify slowed or stopped vehicles, signals are transmitted to the CMS, which then display queue warning messages. Placement of sensors and signs is critical-warnings should activate when a queue extends to within 1-2 miles upstream, depending on speed, to provide adequate driver reaction time. In Missouri, current applications of queue warning rely exclusively on Dynamic Message Signs (DMS) rather than flashing beacons.

909.2.1.5 Integrated Corridor Management

Integrated Corridor Management (ICM) refers to coordinated operations across multiple facilities within a corridor—primarily freeways and parallel arterials. The goal is to manage congestion holistically by making better use of available capacity, balancing demand, and improving traveler information.

909.2.1.6 Transportation Management Centers

Transportation Management Centers (TMCs) serve as the operational backbone of ICM. From TMCs, MoDOT staff monitor real-time traffic conditions, manage ITS devices, coordinate incident response, and adjust strategies such as ramp metering or queue warning. This centralized approach enables proactive management of corridors, ensuring safety and reliability during incidents, work zones, and peak travel periods.

909.2.1.7 Managed Lanes

Managed lanes are roadway segments where access and use are actively regulated to improve traffic flow, safety, or reliability. Common approaches used nationally include bus-only lanes and truck-only lanes. These treatments are typically considered in locations with recurring congestion, limited right-of-way, or freight movement challenges.

At present, Missouri has no active managed lane facilities.

909.2.1.8 Automated Incident Detection

Automated incident detection systems use roadside sensors, video feeds, and software algorithms to identify crashes, stalled vehicles, or other disruptions in real time. These systems often integrate AI-based analytics with CCTV camera footage to detect unusual traffic patterns or stopped vehicles more quickly than traditional operator observation alone. By providing earlier notification of likely incidents, automated detection enhances safety, reduces secondary crashes, and improves response times for emergency and traffic management personnel.

909.2.2 Arterial Operations and Management

Arterial operations strategies improve mobility, safety, and reliability on surface streets through targeted improvements, signal operations, and multimodal accommodations. These strategies focus on reducing congestion at bottlenecks, enhancing intersection performance, and supporting consistent travel across urban and suburban corridors.

In Missouri, arterial management is often a shared responsibility between MoDOT and regional or local partners. For example, the Kansas City region’s Operation Green Light program coordinates arterial signal timing and corridor operations in collaboration with MoDOT and multiple local jurisdictions. Other examples include MoDOT’s partnership with St. Charles in the St. Louis region and collaboration with the City of Springfield and the Ozarks Transportation Organization. Similar arrangements may exist in other regions where MPOs, cities, or counties lead day-to-day arterial management. Practitioners should recognize that depending on the corridor and location, responsibility for arterial operations may rest with another entity, requiring coordination and partnership to ensure consistent system performance.

The following sections outline key strategies for arterial operations and management.

Users:

• Traffic Operations Engineers → Manage signals, coordination, and adaptive timing (909.2.2.3 Traffic Signal Program Management; 909.2.2.4 Traffic Signal Timing and Coordination; 909.2.2.5 Transit Signal Priority).
• Design Engineers → Implement innovative intersections and targeted improvements (909.2.2.1 Targeted Infrastructure Improvements; 909.2.2.2 Innovative Intersection Designs).
• TMC Operators → Oversee corridor signal adjustments and incident response (909.2.2.4 Traffic Signal Timing and Coordination; 909.2.2.6 Arterial Dynamic Shoulder Use).

Policy Coordination – Any consideration or application of the following strategies in Missouri should be closely coordinated with MoDOT’s Central Office of Highway Safety and Traffic (COHST) to ensure consistency with policy, design standards, and operational oversight.

909.2.2.1 Targeted Infrastructure Improvements

Targeted infrastructure improvements are localized enhancements that address recurring bottlenecks or multimodal safety concerns on arterial corridors. Common treatments include new or extended turn lanes to reduce delay at intersections, access control to improve traffic flow and safety, and bus pullouts to minimize transit-related delays. Pedestrian and bicyclist accommodations such as crosswalk improvements, refuge islands, and protected lanes also support safer and more reliable mobility for all users.

909.2.2.2 Innovative Intersection Designs

Innovative intersection designs apply alternative layouts to improve safety and efficiency where traditional designs are constrained. Examples include restricted crossing U-turns (RCUTs), median U-turns, and displaced left-turn (continuous flow) intersections, which reduce conflict points and increase throughput. These designs are increasingly considered where right-of-way is limited, traffic volumes are high, or safety issues persist with conventional layouts.

Additional information can be found in EPG 233.5 Intersection Alternatives.

909.2.2.3 Traffic Signal Program Management

A comprehensive traffic signal program provides the framework for maintaining effective corridor operations. Program elements include monitoring and evaluating existing signal systems, scheduling recurring retiming efforts, and integrating new technologies over time. A proactive, programmatic approach ensures that signals are managed consistently across jurisdictions, providing reliable performance and minimizing inefficient, piecemeal adjustments.

Procedures for signal operation and maintenance are outlined in 902.1.10 Responsibility for Operation and Maintenance (MUTCD Section 4A.10).

909.2.2.4 Traffic Signal Timing and Coordination

Traffic signal timing and coordination strategies are a cost-effective approach to improve arterial operations. By updating signal timing plans and coordinating operations across intersections, agencies can reduce delays and support more predictable travel along corridors. These strategies allow signal operations to reflect current traffic conditions, land use patterns, and system changes, while also providing a foundation for integrating advanced technologies such as adaptive control.

Applications:

• Traffic Signal Retiming – Updating the timing plans for one signalized intersection or a corridor of intersections based on the latest traffic volumes. Retiming is recommended every few years or after significant changes to transportation systems or land use within a given area.
• Traffic Signal Coordination – Coordinating traffic signal timing along a corridor to enable a “green wave” of vehicles traveling through a sequence of signals. Coordination optimizes the splits and offsets of signals to allow for smoother, progressive traffic flow.
• Adaptive Traffic Signal Control – Coordinating traffic signal timing across a network using real-time detector data to accommodate current, prevailing traffic patterns. This allows for dynamic adjustment of timing in response to fluctuating traffic conditions.

909.2.2.5 Transit Signal Priority

Transit signal priority (TSP) strategies adjust signal phasing to reduce delay for buses and improve the efficiency of transit operations. TSP can extend green phases and/or provide early green intervals to help transit vehicles move more consistently through intersections. By enhancing the speed and reliability of bus service, TSP supports multimodal goals and encourages greater use of transit along arterial corridors.

909.2.2.6 Arterial Dynamic Shoulder Use

Arterial dynamic shoulder use provides additional capacity and improves multimodal efficiency by repurposing existing roadway space under defined conditions. Dynamic shoulder use allows roadway shoulders to operate as travel lanes during peak periods or special events, while maintaining their primary role for emergency access during off-peak times. This strategy can help reduce delays, improve vehicle-throughput, and support multimodal goals in areas where right-of-way is constrained and traditional widening is not feasible. Successful implementation requires clear operational policies, appropriate signing and striping, and coordination with enforcement and transit partners to ensure safety and effectiveness.

Although Missouri does not currently implement arterial dynamic shoulder use, the approach may offer targeted benefits in select corridors-especially where traditional widening is not feasible and where shoulders are constructed to full-depth pavement standards.

909.2.3 Freight Operation

Freight operations strategies address truck mobility, parking, and safety near freight generators such as ports and distribution centers. The following sections outline key strategies for freight operations.

Users:

• Transportation Planners → Coordinate freight corridors, permitting, and parking strategies (909.2.3.1 Freight Operations Around Ports and Generators; 909.2.3.2 Truck Parking; 909.2.3.3 Regional Permitting).
• Traffic Operations Engineers → Oversee technology applications and truck restrictions (909.2.3.1 Freight Operations Around Ports and Generators; 909.2.3.4 Technology Applications for Freight; 909.2.3.5 Connected and Automated Freight Vehicles).

Reference MoDOT’s 2022 State Freight and Rail Plan Documents for additional information.

909.2.3.1 Freight Operations Around Ports and Generators

Freight hubs such as ports, intermodal yards, and distribution centers generate concentrated truck activity that can create localized congestion and safety concerns. Targeted operational improvements may include intersection upgrades, dedicated freight lanes, improved signage, or optimized signal timing along key freight corridors. These measures reduce bottlenecks, improve travel time reliability for trucks, and minimize conflicts between freight and passenger vehicles in high-demand areas.

909.2.3.2 Truck Parking

Adequate truck parking is essential for driver safety, freight efficiency, and regulatory compliance. Strategies include the development of new truck parking facilities, upgrades to existing rest areas, and the integration of real-time availability systems that help drivers locate spaces. Reservation tools and wayfinding applications can further support efficient parking use and reduce the safety risks associated with unauthorized shoulder or ramp parking.

909.2.3.3 Regional Permitting

Freight often crosses multiple jurisdictions, and inconsistent permitting processes can add delay and administrative burden. Regional permitting strategies streamline requirements by coordinating across state, county, and local agencies. Harmonizing size, weight, and routing approvals enhances efficiency for carriers while reducing redundant processes for agencies, particularly along high-volume freight corridors.

909.2.3.4 Technology Applications for Freight

Technology provides powerful tools for managing freight mobility. Examples include routing platforms that help drivers avoid weight-restricted bridges or low-clearance structures, monitoring systems that track freight movement in real time, and automated clearance technologies at weigh stations or ports of entry. Collectively, these applications enhance efficiency, improve safety, and provide data to better manage freight corridors.

909.2.3.5 Connected and Automated Freight Vehicles

The freight industry is a leading sector for testing and deploying connected and automated vehicle (CV/AV) technologies. Applications may include platooning, automated truck-mounted attenuators, or fully automated long-haul freight operations. These technologies have the potential to improve safety, reduce driver fatigue, and increase efficiency in freight corridors. Early deployment efforts require coordination with industry, agencies, and technology providers to ensure infrastructure readiness and to evaluate operational impacts.

909.2.4 Vulnerable Road Users

Vulnerable road users (VRUs) are individuals who travel without the protection of an enclosed vehicle and therefore face a greater risk of serious injury in a collision. VRUs include pedestrians, roadway workers, individuals using wheelchairs or other personal mobility devices, bicyclists, motorcyclists, and users of electric scooters and other micromobility devices. The following sections outline key strategies to improve safety, access, and comfort for these users within the transportation system.

Users:

• Design Engineers → Implement bike lanes, pedestrian facilities, and safety enhancements (909.2.4.1 Safety Enhancements; 909.2.4.2 Pedestrian and Accessibility Facilities; 909.2.4.3 Bicycle Lanes and Cycle Tracks).
• Transportation Planners → Support multimodal planning and education programs (909.2.4.1 Safety Enhancements; 909.2.4.4 VRU Education).

909.2.4.1 Safety Enhancements

Selective deployment of safety enhancements should be informed by EPG Category:907 Traffic Safety and tailored to the needs of VRUs. Enhancements may include improved crossings, lighting, signing and pavement markings, speed management strategies, traffic calming measures, work zone protections for roadway workers, and design treatments that reduce conflicts involving motorcyclists and micromobility users.

909.2.4.2 Pedestrian and Accessibility Facilities

Sidewalks, shared-use paths, accessible curb ramps, transit stop connections and enhanced or grade-separated crossings should be prioritized where safety risks, accessibility needs, or network gaps are identified. Integrating these facilities in alignment with Complete Streets principles (EPG 907.10 Complete Streets) helps ensure safe, efficient access for pedestrians and individuals using wheelchairs or other mobility devices.

909.2.4.3 Bicycle Lanes and Cycle Tracks

Where conditions and community priorities warrant, dedicated bike lanes or protected cycle tracks can significantly enhance comfort and safety for bicyclists and other micromobility users, including users of electric scooters and similar devices. MoDOT’s Complete Streets guidance (EPG 907.10 Complete Streets) supports integrating these features into designs that serve all users – including VRUs – within roadway corridors.

909.2.4.4 VRU Education and Outreach

Support community-informed education and outreach programs that promote safe behaviors among VRUs. Programs may address the needs of pedestrians, bicyclists, micromobility users, motorcyclists, individuals with disabilities, and drivers, and may include collaboration with local schools, community organizations, advocacy groups, employers, transit agencies, and public safety partners.

909.2.5 Transit Operation

Transit operations strategies improve speed, reliability, and accessibility of transit services. The following sections outline key strategies for transit operations.

Users:

• Transit Agencies → Operate BRT, implement TSP, and manage transit vehicles (909.2.5.1 Transit Signal Priority; 909.2.5.2 Bus Rapid Transit; 909.2.5.3 Transit-Only Lanes; 909.2.5.4 Transit Operation Vehicles).
• Transportation Planners → Plan multimodal centers and support dynamic transit strategies (909.2.5.2 Bus Rapid Transit; 909.2.5.3 Transit-Only Lanes; 909.2.5.5 Multimodal Transportation Centers).
• Traffic Operations Engineers → Support signal priority and corridor treatments (909.2.5.1 Transit Signal Priority; 909.2.5.2 Bus Rapid Transit; 909.2.5.3 Transit-Only Lanes).

909.2.5.1 Transit Signal Priority

Transit Signal Priority (TSP) strategies modify traffic signal operations to reduce delay and improve on-time arrivals for buses and other transit vehicles.

Additional information on TSP is provided in EPG 909.2.2.5 Transit Signal Priority.

909.2.5.2 Bus Rapid Transit

Bus Rapid Transit (BRT) incorporates a combination of dedicated lanes, intersection treatments, and enhanced stations to provide faster and more reliable bus service. Treatments such as queue jump lanes and high-capacity vehicles further enhance performance. BRT can serve as a cost-effective alternative to rail in high-demand corridors, delivering rapid, frequent, and reliable service with improved passenger amenities.

909.2.5.3 Transit-Only Lanes

Transit-only lanes provide additional capacity and improve multimodal efficiency by repurposing existing roadway space under defined conditions. Transit-only lanes dedicate roadway space to buses, enabling more reliable service and improving schedule adherence in congested corridors. This strategy can help reduce delays, improve person-throughput, and support multimodal goals in areas where right-of-way is constrained and traditional widening is not feasible. Successful implementation requires clear operational policies, appropriate signing and striping, and coordination with enforcement and transit partners to ensure safety and effectiveness.

This strategy may offer targeted benefits in select corridors where shoulders are constructed to full-depth pavement standards.

Policy Coordination – Any consideration or application of the following strategies in Missouri should be closely coordinated with MoDOT’s Central Office of Highway Safety and Traffic (COHST) to ensure consistency with policy, design standards, and operational oversight.

909.2.5.4 Transit Operation Vehicles

Transit vehicle operations may require unique roadway considerations. Streetcars, for example, share corridors with general traffic and necessitate signal coordination and geometric design adjustments for turning movements. Similarly, buses may require accommodations such as bus pullouts, curb extensions, or boarding islands to improve efficiency and passenger safety. These vehicle-specific considerations support smoother operations and minimize conflicts with other modes.

909.2.5.5 Multimodal Transportation Centers

Multimodal transportation centers serve as hubs that integrate multiple travel modes, including bus, rail, bike, and pedestrian connections. These facilities improve regional accessibility by consolidating transfers in a single location and providing amenities such as shelters, ticketing, and real-time traveler information.

In Missouri, existing park-and-ride facilities present opportunities to serve as future multimodal centers. When thoughtfully designed, these centers encourage greater transit use, strengthen first- and last-mile connections, and elevate the role of transit in supporting regional mobility.

REVISION REQUEST 4175 (ON HOLD)

321.2.1.2 Types of Reports

1. The soil survey report touches on foundations by pointing out possible foundation problems. It also contains basic slope recommendations which affect bridge length, soil types and properties for pavement design, depths to rock and type of rock for determining cut quantities, and cut slope recommendations for soil and rock.

2. The preliminary bridge foundation report, which is submitted by the district as an adjunct to the soil survey report, is usually furnished to the Bridge Unit for their guidance in preparing preliminary bridge layouts and to the Materials Engineering Unit for guidance in conducting a more detailed foundation investigation. (Preliminary borings for such reports may be omitted where access problems are especially difficult.)

3. The final foundation investigation report will provide the requested properties from Form A of the Bridge Division Request for Soil Properties in accordance with EPG Sections 320, 321, 700 and other applicable sections. The report will also provide seismic properties as requested on Form B. The Bridge Division or District will provide the preliminary structure layout and location of each foundation location. The Geotechnical Section will determine boring locations and sampling frequency based on guidance in, EPG 321.2 Geotechnical Guidelines, and specific site conditions. The Geotechnical Section may make recommendations for specific foundation types if site conditions require special considerations. The intent is to provide the Bridge Division or District with the information needed to develop designs for the foundation types practical for a particular site. Rules of thumb as to what is practical have been developed jointly by the Geotechnical Section and the Bridge Division. These are discussed in the applicable sections within the EPG.

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701 Drilled Shafts

Substructure foundations may be designed to transmit loads to foundation strata by concrete columns cast in drilled holes. See EPG 751.37 Drilled Shafts for design guidance and additional information.

This type of foundation is identified in Sec 701 of the Standard Specifications as Drilled Shafts. A drilled shaft is generally considered a deep foundation.

Drilled shafts for bridge structures:

Drilled shafts for bridge structures shall be constructed with a permanent casing and rock socketed. Requirements for plan reporting of steel casing are given in EPG 751.37.1.3 Casing.

The shaft portion of a drilled shaft is founded on rock (limestone, dolomite or other suitable material with q_u ≥ 100 ksf) or weak rock (shale or other suitable material with 5 ksf ≤ q_u ≤ 100 ksf) with a smaller diameter rock socket drilled into same. The inspector should carefully study all general specifications and special provisions pertaining to drilled shafts and become familiar with the designer's intent.

The integrity of the rock socket shall be verified by a foundation inspection hole. This is usually performed after the shaft is drilled. Setting up over a drilled hole can be difficult. The contractor can perform the inspection hole in advance if they submit a procedure that assures the correct location is cored. If the integrity of the cores are questionable the Bridge Division should be contacted to see if the rock socket length should be extended.

Most problems with drilled shafts occur during the concrete pour. The concrete placement requirements in Sec 701 should be reviewed carefully.

An anomaly may be detected on a Cross Hole Sonic log test. If, on further investigation, there is a confirmed defect what are some of the steps needed to remediate the defect?

1. The contractor is responsible for submitting a remediation plan for the repair.

2. The plan should include as a minimum the following:

a) The area of deficient material must be clearly defined using coring or other means.

b) The clean-out process is typically accomplished by flushing the weak material. The access holes needed, water pressure used, and disposal of the soils should be addressed.

c) Confirmation of the deficient material removal must be made. This can be accomplished by camera inspection, CSL, or by other means acceptable to the engineer.

d) The grouting plan should include: grouting type, grout mix design including w/c ratio, complete pressure grouting timeline. The grouting timeline should include placement times, pressure, volume, refusal criteria.

3. A final confirmation of the effectiveness of the grouting should be made. This is typically accomplished by coring. The number of cores required, and depth shall be submitted to the engineer for approval prior to coring. If all the CSL tubes are still usable, a final CSL can be made for acceptance. The engineer of record for the design should be consulted for final acceptance.

Question: Per Sec 701.4.17.2.1 Installation of Pipes, “The pipes shall be filled with water and plugged or capped before shaft concrete is poured.” Why is this necessary?

The water in the tube helps to regulate the temperature of the CSL tube. Without the water, the tube will heat up from the hydrating concrete and cause de-bonding. This de-bonding from the concrete will cause erroneous CSL readings and show up as an anomaly. Typically, de-bonding is more prevalent in the upper 6 ft. of the tube. The water also serves a second purpose: it helps the energy transmission from the wall of the tube to the probes and vice versa.

Drilled shafts for non-bridge structures:

Drilled shafts for non-bridge structures are typically designed and constructed without casing. Permanent casing is not allowed except for special designs.

The shafts may be embedded into rock when soil overburden depth is inadequate for properly anchoring the foundation. If overburden soils are unstable and conduit access is not required in the perimeter of the shaft, temporary casing may be used with an oversized shaft to allow excavation into rock at the required diameter.

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751.1.2.20 Substructure Type

Once the signed Bridge Memo and the Borings are received, the entire layout folder should be given to the Preliminary Detailer (requested by SPM, assigned by Structural Resource Manager). The Preliminary Detailer will copy the appropriate MicroStation drawings into their own directory. (Do not rename files) Consultants contact Structural Liaison Engineer. The Preliminary Detailer will then draw the proposed bridge on the plat and profile sheets. The bridge should also be drawn on the contracted profile for a perspective of the profile grade relative to the ground line for drainage considerations. The Preliminary Detailer will also generate a draft Design Layout Sheet and then return the layout folder to the Preliminary Designer for review.

The Preliminary Designer will then choose the substructure types for each of the bents. Pile cap bents without concrete encasement are less expensive than column bents but they should not be used at the following locations:

• Where drift has been identified as a problem
• Where the height of the unbraced piling is excessive and kl/r exceeds 120 (kl/r<120 is generally preferred) (take scour into account)
• Where the bent is adjacent to traffic (grade separations)

Encased pile cap bents may be considered if economical. Embed concrete encasement 2 ft. (minimum) below the top of the lowest finished groundline elevation, unless a greater embedment is required for bridge scour. Greater embedment up to 5 or 6 ft. may be considered in situations where anticipated ground line elevation can fluctuate more severely. (Be sure to account for excavation quantities for deeper embedment.) Provision for encasing piles may be considered at the following locations:

• Where drift is a concern and protection is required
• Where larger radius of gyration is necessary and therefore improved buckling resistance for locations where the exposed unbraced column length is large
• Not exclusively where the piles at the pile/wall interface may experience wet/dry cycles and/or excessive periods of ground moisture

For column bents, an economic analysis should be performed to compare drilled shafts to footings. Footings are not recommended for stream crossings where scour potential is identified. For grade separations, assume the top of drilled shaft casing is located at least one foot below the ground line. For shallow rock conditions, consideration should also be given to eliminating the cased portion of the shaft and placing the column directly over an oversized rock socket. Top of drilled shaft casing for stream crossings should consider the following criteria, and with SPM or SLE approval, select the appropriate elevation to balance risk for the anticipated conditions at time of construction:

• 10-year flood elevation
• 1 foot above ordinary high water elevation
• Elevation of nearest overbank
• 3 feet above low water elevation

End Bents are usually pile cap bents; however, if quality rock is abundant at or just below the bottom of beam elevation, a stub end bent on spread footings may be used. If you have any doubt about the suitability and uniformity of the rock, you can still use a pile cap end bent. Just include prebore to get a minimum of 10 ft. of piling. If you have concerns about temperature movements, you can require that the prebore holes be oversized to allow for this movement.

For any pile cap bents, where steel piles are to be placed near a fluctuating water line or near a ground line where aggressive soil conditions exist or anticipated to exist in the future, corrosion can result in substantial material loss in pile sections over time, either slowly or rapidly. Galvanized steel piling is required for all new pile cap bents to be used as a deterrent to both accelerated and incidental pile corrosion as commonly seen in the field. Further, conditions like known in corrosive soils, some stream crossings with known history of effects on steel piles and grounds subject to stray currents, these conditions should affect the decision of whether pile cap bents can be effectively utilized. The potential effects of corrosion and the potential deterioration from environmental conditions should always be considered in the determination and selection of the steel pile type and steel pile cross-section (size of HP pile or casing thickness), and in considering the long-term durability of the pile type in service.

Once the substructure type has been determined, re-examine your Preliminary Cost Estimate and notify the district if it needs to be adjusted.

Galvanized Steel Piles

Galvanizing shall be required for all steel piles. Utilizing galvanized steel piles and pile bracing members shall be in addition to the requirements of Standard Specifications Sec 702 except that protective coatings specified in Sec 702 will not be required for galvanized piles or galvanized bracing members.

Where galvanized steel piling is expected to be exposed to severe corrosive conditions, consideration can be given to increased steel pile thickness or consideration of a reduced loaded steel area for bearing, or conditions mitigated to prevent long term corrosivity risk . This equally applies to the potential corrosion and early deterioration of permanent steel casing used for drilled shafts though they are not required to be galvanized. For all cases, further consideration beyond normal practice should be given to investigating corrosion protection, rate of corrosion as it relates to steel thickness design and expected service life including galvanizing losses, corrosion mitigation or different substructure support in order to meet a 75 year or longer design life. For additional information refer to LRFD 10.7.5 and 10.8.1.5. Consult with the Structural Project Manager or Structural Liaison Engineer to determine options and strategy for implementation.

All Bridge and Retaining Wall Piles (For Example, abutment piles, wing wall piles, intermediate pile cap bent piles and pile cap footing piles)

All surfaces of piles shall be galvanized to a minimum galvanized penetration (elevation) or its full length based on the following guidance. The minimum galvanized penetration (elevation) shall be estimated in preliminary design and finalized in final design. The minimum galvanized penetration (elevation) or full length will be shown on the design layout.

Guidance for determining minimum galvanized penetration (elevation):

The designer shall establish the limits of galvanized structural steel pile (i.e., HP pile and CIP pile). All exposed pile plus any required length below ground shall be galvanized. Based on required galvanized pile length determine and show Minimum Galvanized Penetration (Elevation) or Full Length on the Design Layout and on the plans.

When glacial material or other hard material is identified in the geotechnical report discuss with SPM and consider galvanizing full length of pile to avoid the scenario where friction pile may potentially be cut-off once the geotechnical capacity is reached but the depth for galvanization is inadequate.

	Required Pile Galvanizing For Nonscour	Required Pile Galvanizing For Channel Scour	Required Pile Galvanizing For Channel Migration
Estimated Pile Length ≤ 50 feet	Full Length of Pile	Full Length of Pile	Full Length of Pile
Estimated Pile Length > 50 feet	20 feet (in ground)1	20 feet (in ground)1, but not less than 5 feet below max. scour depth.	20 feet (in ground)1, but not less than 5 feet below stream bed elev.
1 “In ground” is measured from finished ground line on intermediate bents, and bottom of beam cap for abutments.

For retaining walls supported on piles, the minimum galvanized penetration (elevation) for piles shall be “Full Length of Pile” for estimated pile length up to 50 feet and 15 feet below bottom of wall for estimated pile length greater than 50 feet.

For bridge end bents on piles with embankments supported by MSE walls, the minimum galvanized penetration (elevation) for piles shall be “Full Length of Pile” for estimated pile length up to 50 feet and 15 feet below top of leveling pad for estimated pile length greater than 50 feet.

Temporary Bridge Piles

Protective coatings are not required in accordance with Sec 718. Galvanized pile is not required. All HP piles driven to rock shall require pile point reinforcement.

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751.1.2.24 Drilled Shafts

Drilled shafts are to be used when their cost is comparable to that of large cofferdams and footings. Other examples include when there are subsurface items to avoid (culverts, utilities, etc.) or when there are extremely high soil pressures due to slope failures.

Drilled shafts shall be constructed with a permanent casing and rock socketed.

The Final Foundation Investigation Report (or geotechnical report) for drilled shafts should supply you with the anticipated tip of casing, nominal tip resistance, nominal tip resistance factor, nominal side resistance, nominal side resistance factor as well as the recommended elevations for which the resistance values are applicable.

The Design Layout Sheet should include the following information:

• Top of Drilled Shaft Elevation
• Anticipated Tip of Casing Elevation
• Anticipated Top of Sound Rock Elevation

Bent	Elevation	Nominal Axial Compressive Resistance (Side Resistance) (ksf)	Side Resistance Factor for Strength Limit State	Nominal Axial Compressive Resistance (Tip Resistance) (ksf)	Tip Resistance Factors for Strength Limit States

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751.4.1 Reinforced Concrete

Classes of Reinforced Concrete

Below are classes of concrete for each type or portion of structure:

Box Culverts		B-1
Retaining Walls		B or B-1
Superstructure (General)		B-2
	Curbs and Parapets	B-1
	Type A, B, C, D, G and H Barriers	B-1
	Sidewalks	B-2
	Raised Median	B-2
	Slabs	B-2
	Box Girders	B-2
	Deck Girders	B-2
	Prestressed Precast Panels	A-1
	Prestressed I - Girders	A-1
	Prestressed Double -Tee Girders	A-1
	Integral End Bents (Above lower construction joint)	B-2
	Semi-Deep Abutments (Above construction joint under slab)	B-2
Substructure (General)		B
	Integral End Bents (Below lower construction joint)	B
	Non-Integral End Bents	B
	Semi-Deep Abutments (Below construction joint under slab)	B
	Intermediate Bents	B (*)
	Intermediate Bent Columns, End Bents (Below construction joint at bottom of slab in Cont. Conc. Slab Bridges)	B-1
	Footings	B
	Drilled Shafts (except per Standard Plans 903.15)	B-2
	Drilled Shafts (per Standard Plans 903.15)	B
	Cast-In-Place Pile	B-1
(*) In special cases when a stronger concrete is necessary for design, Class B-1 may be considered for intermediate bents (caps, columns, tie beams, web beams, collision walls and/or footings).

Unit Stresses of Reinforced Concrete

Class of Concrete	Aggregate Maximumsize (Inches)	Cement Factor (barrels percubic yard)	$f^{\prime }c$ (psi)	$fc$ (psi)	$n$ (*)	$E_c$ (ksi)
A-1	3/4	1.6 (Min.)	5,000	2,000	6	4074
B	1	1.4 (Min.)	3,000	1,200	10	3156
B-1	1	1.6 (Min.)	4,000	1,600	8	3644
B-2	1	1.875 (Min.)	4,000	1,600	8	3644

(*) Values of n for computations of strength only.

Reinforcing Steel
Reinforcing Steel (Grade 60)	$F_y$ = 60 ksi

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751.37.1.2 Materials

Commentary for EPG 751.37.1.2 Materials

Concrete used for drilled shaft for traffic structures in accordance with standard plan 903.15 shall be Class B concrete with minimum compressive strength, f’_c = 3 ksi. For all other drilled shaft construction concrete shall be Class B-2 with minimum compressive strength, f’_c = 4 ksi.

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751.37.1.3 Casing

Commentary for EPG 751.37.1.3 Casing

Drilled shafts for bridge structures:

All drilled shafts shall have permanent casing installed through overburden soils to prevent caving of these soils during construction. Drilled shafts shall be socketed into bedrock. Welded or seamless steel permanent casing shall be in accordance with Sec 701.

Rock sockets shall be uncased.

Permanent Casing Thickness Design and Plan Reporting:

Any drilled shaft for a major bridge over a river or lake or any drilled shaft longer than 80 feet or any drilled shaft greater than 6 feet in diameter shall have a minimum casing thickness of 1/2 inch specified unless a greater thickness is required by design for strength. The thickness of casing in either case shall be shown on the bridge plans and noted as a minimum.

All other drilled shafts shall not have a minimum casing thickness specified unless a specific thickness is required by design for strength. The minimum thickness in the latter case shall be shown on the bridge plans and noted as a minimum.

For drilled shaft stiffness computations and load distribution analysis, use the minimum casing thickness required. When a minimum casing thickness is not required, assume a casing thickness of 3/8” for the analysis.

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751.37.1.5 Related Provisions

Commentary for EPG 751.37.1.5 Related Provisions

The provisions of these guidelines were developed presuming that design parameters required to apply the provisions are established following current MoDOT site characterization protocols as described in EPG 321. Specific attention is drawn to EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation. The provisions provided in these guidelines presume that parameter variability, as generally represented by the coefficient of variation (COV), is established following procedures in EPG 321.3.

Sign structure drilled shaft supports are the exception. Sign structure standard drilled shafts are developed using assumed soil properties and following AASHTO LRFD Bridge Design Specifications 9^th Edition for design. Site specific designs for drilled shafts for sign structure support may also follow AASHTO LRFD Bridge Design Specifications 9^th Edition if there is not enough geotechnical information available to establish the COV.

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751.37.1.6 Drilled Shaft General Detail Considerations

For Seismic detail requirements for seismic design category, SDC B, C and D, See EPG 751.9.1.2 LRFD Seismic Details.

Pay items shown in above table are for example only, show actual pay items and quantities in plan details for specific project.

Notes:

(1) Number of pipes (equally spaced) for Sonic Logging Testing (for bridge structures only):

Diameter ≤ 2.5 ft: 2 pipes

Diameter >2.5 ft but ≤ 3.5 ft: 3 pipes

Diameter >3.5 ft but ≤ 5.0 ft: 4 pipes

Diameter >5.0 ft but ≤ 8.0 ft: 5 pipes

Diameter >8.0 ft: 6 pipes

Single diameter reinforcing cage is typically used. Modify details based on design for single or multiple-diameter cages and splice location(s).

See EPG 751.37.1.3 for casing requirements for bridge structures and non-bridge structures.

When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.

See EPG 751.50, G8, for notes to include for drilled shafts and rock sockets (starting at G8.1).

(2) See EPG 751.37.1.1 Dimensions and Nomenclature for Design Aid: Minimum Rock Socket Length.

(3) When difference between drilled shaft and column diameter is 6" a single reinforcement cage is typically used for the socket and shaft and the vertical reinforcement extends into the column. A separate column steel cage is then placed around the protruding shaft reinforcement without requiring an adjustment to minimum cover for rock socket or column reinforcement. When difference between drilled shaft and column diameter is 12” either the vertical column steel or dowels will need to be extended into the shaft or the cover in the socket and shaft will need to be increased to allow the shaft reinforcement to extend into the column. In the former scenario an optional construction joint is recommended as discussed in note 4 for oversized shafts. In the latter scenario the same number of vertical bars should be used in the shaft and column to allow the shaft bars to be tied to the column cage. Any reduction in cage diameter required for fit-up shall be considered in design.

(4) When difference between drilled shaft and column diameter is greater than 12" (oversized shaft generally 18" to 24" larger than column), show "Optional construction joint" at bottom of column/dowel reinforcement in the drilled shaft and use EPG 751.50 Standard Detailing Notes G8.8 and G8.9 in plan details.

Bridge Standard Drawings (Drilled Shafts - DSS → As Built Drilled Shaft Data [DSS_01])

As Built Drilled Shaft Data (PDF)

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751.37.2 General Design Procedure and Limit States

Commentary for EPG 751.37.2 General Design Procedure and Limit States

Drilled shafts should be sized (diameter and length) to support the required factored loads in the most cost effective manner possible without excessive deflections. The initial diameter and length of drilled shafts are generally established considering vertical loading at the strength limit state(s) according to EPG 751.37.3. The resulting shaft should then be evaluated at the axial and lateral serviceability limit states (settlement and lateral deflection) according to EPG 751.37.4 and EPG 751.37.5, where the shaft dimensions shall be adjusted if serviceability requirements are not satisfied.

The Strength Limit State and applicable Extreme Event Limit States shall be investigated when calculating the soil and structural resistance of the drilled shaft. The Service I Limit State shall be used when evaluating lateral deflection and settlement.

Guidance

There is one type of drilled shaft construction for bridge structures. There are three types of drilled shaft construction for non-bridge structures, but only two types need be considered for design. See EPG 751.37.1.3 Casing.

Drilled shafts for bridge structures:

Permanently cased shaft through soil and socketed into rock. A reduced shaft diameter for rock socket is required. This case shall be used for all MoDOT bridge structures. For axial loading and settlement computations substitute D with D_s and L with L_s which are equal to the diameter and length of the rock socket since the required resistance to loading and settlement are computed for segment of the shaft in rock only (Rock sockets to be installed through casing shall have diameters 6” less than the inside diameter of the casing to allow for clearance and insertion of rock excavation re-tooling equipment).

Drilled shafts for non-bridge structures:

1. Uncased shaft through soil and not socketed into rock. For axial loading and settlement computations use D = diameter of shaft.

2. Uncased shaft through soil and rock. Similar to (1) because the shaft diameter is assumed to be constant between soil and rock.

3. Temporarily cased shaft through soil with an uncased and reduced or same shaft diameter in rock. This method is optional for the contractor in limited scenarios and requires the shaft in soil to be oversized by six inches with respect to the shaft diameter shown on the plans.

Permanently cased shafts shall not be allowed to use frictional resistance of the soil for either a drilled shaft with or without a rock socket.

Temporarily cased shafts may use the frictional resistance of the soil only for the case where a rock socket is not used (see the Geotechnical Section).

Note on Definitions:

1. Where L_,i is defined, L_i shall mean the length of the shaft segment through soil or through rock.

2. Where L is defined, L shall mean overall shaft length including the length of the rock socket.

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751.37.3 Design for Axial Loading at Strength Limit State

Commentary for EPG 751.37.3 Design for Axial Loading at Strength Limit State

Geotechnical resistance to axial loading at the relevant strength limit state shall be computed as the sum of tip resistance and side resistance unless conditions are present that may prevent reliable mobilization of tip resistance (e.g. karst conditions with known or likely voids that cannot be specifically identified or characterized). Shafts should be sized such that the factored geotechnical resistance to axial loads exceeds the factored axial loads:

$R_R=R_{sR}+R_{pR}\ge \gamma Q$

(consistent units of force)

Equation 751.37.3.1

where:

R_R = factored axial shaft resistance (consistent units of force),

R_sR = factored side resistance (consistent units of force),

R_pR = factored tip resistance (consistent units of force) and

$\mathit{\gamma }Q$ = factored load for the appropriate strength limit state (consistent units of force).

Tip resistance and side resistance shall be computed according to the provisions of EPG 751.37.3 for the material type(s) encountered. The Structural Project Manager or Structural Liaison Engineer shall be consulted before utilizing design methods other than those provided in EPG 751.37.3 for calculating the geotechnical resistance of drilled shafts.

The factored side resistance for drilled shafts shall be established from factored unit side resistance values for the relevant soil/rock conditions as provided in this article. For stratified ground conditions or where the shaft dimensions change (e.g. at tip of temporary casing for non-bridge structure, or at top of rock socket for bridge structure), the shaft shall be divided into segments with practically uniform shaft geometry and soil/rock properties and unit side resistance values determined for each shaft segment. The total factored side resistance shall then be computed as the sum of the factored resistance values for each shaft segment:

$R_{sR}=\sum _{i=1}^n(q_{sR-i}\cdot A_{s-i})=\sum _{i=1}^n({\varphi }_{qs-i}\cdot q_{s-i}\cdot \pi \cdot D_i\cdot L_i)$

(consistent units of force)

Equation 751.37.3.2

where:

n = number of shaft segments,

$q_{sR-i}={\varphi }_{qs-i}\cdot q_{s-i}$ = factored unit side resistance for shaft segment i (consistent units of stress),

$A_{s-i}=\pi \cdot D_i\cdot L_i$ = perimeter interface area for shaft segment i (consistent units of area),

${\mathit{\varphi }}_{qs-i}$ = resistance factor for unit side resistance along shaft segment i (dimensionless),

${\mathbf{q}}_{s-i}$ = nominal unit side resistance along shaft segment i (consistent units of stress),

D_i = shaft diameter for shaft segment i (consistent units of length), and

L_i = length of shaft segment i (consistent units of length).

${\mathit{\varphi }}_{qs-i}$ and ${\mathbf{q}}_{s-i}$ shall be determined in accordance with the provisions of this article, based on the material type present along the respective shaft segment.

Side resistance shall generally be neglected or reduced, as recommended by the Geotechnical Section, over shaft segments with permanent casing and over any length of rock socket that is deemed unusable.

The factored tip resistance for drilled shafts shall be established from factored unit tip resistance values for the relevant soil/rock conditions as provided in this article. The appropriate tip resistance shall be established for the soil/rock located between the tip of the shaft and two diameters below the tip of the shaft. The factored tip resistance shall be computed as

$R_{pR}=q_{pR}\cdot A_p={\varphi }_{qp}\cdot q_p\cdot \pi \cdot \frac{D^2}{4}$

(consistent units of force)

Equation 751.37.3.3

where:

$q_{pR}={\varphi }_{qp}\cdot q_p$ = factored unit tip resistance (consistent units of stress),

$A_p=\pi \cdot \frac{D^2}{4}$ = cross-sectional area of the shaft at the tip (consistent units of area),

${\mathit{\varphi }}_{qp}$ = resistance factor for unit tip resistance (dimensionless),

${\mathbf{q}}_p$= nominal unit tip resistance (consistent units of stress), and

D = shaft diameter at the tip of the shaft (consistent units of length).

${\mathit{\varphi }}_{qp}$ and ${\mathbf{q}}_p$ shall be determined in accordance with the provisions of this article, based on the material type present within a depth of 2D below the tip of the shaft.

Tip resistance shall be neglected, as recommended by the Geotechnical Section, when the shaft tip is located within karstic rock or other conditions where tip resistance cannot be reliably determined.

The specific methods and resistance factors for determining nominal and factored side and tip resistance shall be selected based on the material type(s) present along the sides and beneath the tip of the shaft:

• EPG 751.37.3.1 shall generally be followed to estimate resistance for shafts in rock from results of uniaxial compression tests on intact rock core with uniaxial compressive strengths (q_u ) greater than 100 ksf;

• EPG 751.37.3.2 shall generally be followed to estimate resistance for shafts in weak rock from results of uniaxial compression tests on rock core with uniaxial compressive strengths (q_u ) greater than 5 ksf but less than 100 ksf;

• EPG 751.37.3.3 shall generally be followed to estimate resistance for shafts in weak rock from results of Standard Penetration Tests with equivalent N-values (N_eq ) less than 400 blows/foot;

• EPG 751.37.3.4 shall generally be followed to estimate resistance for shafts in weak rock from results of Texas Cone Penetration Tests with measured penetrations (TCP) greater than 1 inch/100 blows but less than 10 inches/100 blows;

• EPG 751.37.3.5 shall generally be followed to estimate resistance for shafts in weak rock from results of Point Load Index Tests with Point Load Indices (I_s(50) ) less than 40 ksf;

• EPG 751.37.3.6 shall generally be followed to estimate resistance for shafts in cohesive soils with undrained shear strengths (s_u ) less than 5 ksf; and

• EPG 751.37.3.7 shall generally be followed to estimate resistance for shafts in cohesionless soils.

Additional guidance on selection of specific methods and resistance factors based on the material types encountered is provided in the commentary to these guidelines.

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751.37.3.7 Axial Resistance for Individual Drilled Shafts in Cohesionless Soils

Commentary for EPG 751.37.3.7 Axial Resistance for Individual Drilled Shafts in Cohesionless Soils

Side Resistance for Drilled Shafts in Cohesionless Soils

The nominal unit side resistance for shaft segments located in cohesionless soils shall be computed using the “β-method” as

$q_s=\beta \cdot {\sigma }_v^{\text{'}}$

(consistent units of stress)

Equation 751.37.3.21

where:

q_s = nominal unit side resistance for the shaft segment (consistent units of stress),

β = an empirical correlation factor (dimensionless) and

σ'_v = average vertical effective stress for the soil along the shaft segment (consistent units of stress).

The value for β shall be taken as (O’Neill and Reese, 1999)

$\beta =1.5-0.135\sqrt{z}$	(for N60 ≥ 15)	Equation 751.37.3.22a
$\beta =\frac{N_{60}}{15}\cdot (1.5-0.135\sqrt{z})$	(for N60 < 15)	Equation 751.37.3.22b

where 0.25 ≤ β ≤ 1.2 and

z = depth below ground surface to center of shaft segment (ft.) and

N₆₀ = average SPT N-value corrected for hammer efficiency (blows/ft).

If permanent casing is used, the side resistance shall be ignored for the cased portion.

The resistance factor ${\mathit{\varphi }}_{qs}$ to be applied to the nominal unit side resistance shall be taken as 0.55 (LRFD Table 10.5.5.2.4-1).

Tip Resistance for Drilled Shafts in Cohesionless Soils

The nominal unit tip resistance for shafts founded on cohesionless soils shall be computed from corrected SPT N-values, N₆₀ (O’Neill and Reese, 1999).

For N_60≤50:

$q_p=1.2\cdot N_{60}\le 60ksf$

(ksf)

Equation 751.37.3.23

where:

q_p = nominal unit tip resistance for the shaft (ksf) and

N₆₀ = average SPT N-value corrected for hammer efficiency (blows/ft).

For N₆₀ ≥ 50:

$q_p=0.59\cdot {\sigma }_v^{\text{'}}\cdot \left(N_{60}\right(\frac{p_a}{{\sigma }_v^{\text{'}}}){)}^{0.8}$

(ksf)

Equation 751.37.3.24

where:

q_p = nominal unit tip resistance for the shaft (ksf),

N₆₀ = average SPT N-value corrected for hammer efficiency (blows/foot),

p_a = 2.12 ksf = atmospheric pressure (ksf).

${\sigma }_v^{\text{'}}$ = vertical effective stress for the soil at the tip of the shaft (ksf).

Note that these expressions are dimensional so values must be entered in the units specified.

The resistance factor ${\mathit{\varphi }}_{qp}$ shall be taken as 0.50 for Equation 751.37.3.23 and as 0.55 for Equation 751.37.3.24.

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751.37.4.1 Settlement of Individual Drilled Shafts using Approximate Method

Commentary on EPG 751.37.4.1 Settlement of Individual Drilled Shafts using Approximate Method

Prediction of factored settlement due to factored service loads shall be determined as follows depending on the magnitude of factored loads relative to the magnitude of factored side and tip resistance:

If $\gamma Q\le R_{sR}+0.1R_{pR}$:

${\delta }_R=0.005\cdot D\cdot \frac{\gamma Q}{R_{sR}+0.1R_{pR}}+{\delta }_{eR}$

(consistent units of lengths)

Equation 751.37.4.3

where:

$\mathit{\gamma }Q$ = factored load for the appropriate serviceability limit state (consistent units of force),

R_sR = total factored side resistance determined according to the provisions of this article (consistent units of force),

R_pR = factored tip resistance determined according to the provisions of this article (consistent units of force),

δ_R = factored total settlement of shaft due to factored service loads (consistent units of length),

D = shaft diameter (consistent units of length) and

δ_eR = factored elastic compression of the unsupported length of the shaft (consistent units of length).

If $R_{sR}+0.1R_{pR}\le \gamma Q\le R_{sR}+R_{pR}$ :

${\delta }_R=0.005\cdot D+0.045\cdot D\cdot \left(\frac{\gamma Q-R_{sR}-0.1R_{pR}}{0.9\cdot R_{pR}}\right)+{\delta }_{eR}$

(consistent units of lengths)

Equation 751.37.4.4

where:

$\mathit{\gamma }Q$ = factored load for the appropriate serviceability limit state (consistent units of force),

R_sR = total factored side resistance determined according to the provisions of this article (consistent units of force),

R_pR = factored tip resistance determined according to the provisions of this article (consistent units of force),

δ_R = factored total settlement of shaft due to factored service load (consistent units of length),

D = shaft diameter (consistent units of length) and

δ_eR = factored elastic compression of the unsupported length of the shaft (consistent units of length).

Note that if $\gamma Q\ge R_{sR}+R_{pR}$, the factored service load exceeds the maximum factored resistance of the shaft and the limit state cannot be satisfied without increasing the dimensions of the shaft.

The factored side resistance in Equations 751.37.4.3 and 751.37.4.4 shall be established from factored unit side resistance values for the relevant soil/rock conditions as provided in this article. For stratified ground conditions or where the shaft dimensions change, the shaft shall be divided into segments with practically uniform shaft geometry and soil/rock properties and unit side resistance values determined for each shaft segment. The total factored side resistance shall then be computed as the sum of the factored resistance values for each shaft segment:

$R_{sR}=\sum _{i=1}^n(q_{sR-1}\cdot A_{s-i})=\sum _{i-1}^n({\varphi }_{\delta s-i}\cdot q_{s-i}\cdot \pi \cdot D_i\cdot L_i)$

(consistent units of force)

Equation 751.37.4.5

where:

n = number of shaft segments,

$q_{sR-i}={\varphi }_{\delta s-i}\cdot q_{s-i}$ = factored unit side resistance for shaft segment i (consistent units of stress),

$A_{s-i}=\pi \cdot D_i\cdot L_i$ = perimeter interface area for shaft segment i (consistent units of area),

${\mathit{\varphi }}_{\delta s-i}$ = settlement resistance factor for side resistance along shaft segment i (dimensionless),

q_s-i = nominal unit side resistance along shaft segment i (consistent units of stress),

D_i = shaft diameter for shaft segment i (consistent units of length) and

L_i = length of shaft segment i (consistent units of length).

Values for q_s-i shall be determined in accordance with the provisions of EPG 751.37.3, based on the material type present along the respective shaft segments. Values for ${\mathit{\varphi }}_{\delta s-i}$ shall be established as provided subsequently in this article. Side resistance shall generally be neglected or reduced, as recommended by the Geotechnical Section, over shaft segments with permanent casing and over any length of rock socket that is deemed unusable for consistency with evaluations performed for strength limit states.

The factored tip resistance in Equations 751.37.4.3 and 751.37.4.4 shall be established from factored unit tip resistance values for the relevant soil/rock conditions as provided in this article. The appropriate tip resistance shall be established for the soil/rock located between the tip of the shaft and a distance of 2D below the tip of the shaft. The factored tip resistance shall be computed as

$R_{pR}=q_{pR}\cdot A_p={\varphi }_{\delta p}\cdot q_p\cdot \pi \cdot \frac{D^2}{4}$

(consistent units of force)

Equation 751.37.4.6

where:

$q_{pR}={\varphi }_{\delta p}\cdot q_p$ = factored unit tip resistance (consistent units of stress),

$A_p=\pi \cdot \frac{D^2}{4}$ = cross-sectional area of the shaft at the tip (consistent units of area),

${\mathit{\varphi }}_{\delta p}$ = settlement resistance factor for tip resistance (dimensionless),

q_p = nominal unit tip resistance (consistent units of stress) and

D = shaft diameter at the tip of the shaft (consistent units of length).

The value for q_p shall be determined in accordance with the provisions of EPG 751.37.3, based on the material type present within a depth of 2D below the tip of the shaft. The value for ${\mathit{\varphi }}_{\delta p}$ shall be established as provided subsequently in this article. For consistency with evaluations for strength limit states, tip resistance shall be neglected, as recommended by the Geotechnical Section, when the shaft tip is located within karstic rock or other conditions where tip resistance cannot be reliably determined.

The factored elastic compression of the unsupported length of the shaft shall be determined as

${\delta }_{eR}=\frac{\gamma Q(L-L_s)}{{\varphi }_{\delta e}\cdot E_p{A}_p}$

(consistent units of length)

Equation 751.37.4.7

where:

δ_eR = factored elastic compression of the unsupported length of the shaft (consistent units of length),

$\mathit{\gamma }Q$ = factored load for the appropriate serviceability limit state (consistent units of force),

L = overall shaft length (consistent units of length),

L_s = length of the rock socket (consistent units of length),

E_p = nominal modulus of elasticity for the shaft (consistent units of stress),

A_p = nominal shaft area (consistent units of area) and

${\mathit{\varphi }}_{\mathit{\delta }e}$ = settlement resistance factor for elastic compression of the shaft.

Values for the settlement resistance factor for elastic compression of the shaft shall be taken from Table 751.37.4.1 according to the operational importance of the structure.

Table 751.37.4.1 Settlement resistance factors for elastic compression of drilled shafts

Operational Importance	Settlement Resistance Factor, Φδe
Minor or Low Volume Route	0.68
Major Route	0.64
Major Bridge <$100 million	0.61
Major Bridge >$100 million	0.60

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Rock

Settlement resistance factors to be applied to side resistance for shaft segments through rock shall be determined from Figure 751.37.4.1.1 based on the coefficient of variation of the mean uniaxial compressive strength, $CO{V}_{\overline{q_u}}$. Values for $CO{V}_{\overline{q_u}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean uniaxial compressive strength for the rock over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on rock shall similarly be determined from Figure 751.37.4.1.2 based on values for $CO{V}_{\overline{q_u}}$ that reflect the variability of the mean uniaxial compressive strength for the rock over the distance 2D_s below the tip of the shaft.

Fig. 751.37.4.1.1 Settlement resistance factors for side resistance of drilled shafts in rock from uniaxial compression test measurements using approximate method.

Fig. 751.37.4.1.2 Settlement resistance factors for tip resistance of drilled shafts in rock from uniaxial compression test measurements using approximate method.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Weak Rock from Uniaxial Compression Tests on Rock Core

Settlement resistance factors to be applied to side resistance for shaft segments through weak rock shall be determined from Figure 751.37.4.1.3 based on the coefficient of variation of the mean uniaxial compressive strength, $CO{V}_{\overline{q_u}}$. Values for $CO{V}_{\overline{q_u}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean uniaxial compressive strength for the rock over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on weak rock shall similarly be determined from Figure 751.37.4.1.4 based on values for $CO{V}_{\overline{q_u}}$ that reflect the variability of the mean uniaxial compressive strength for the rock over the distance 2D_s below the tip of the shaft.

Fig. 751.37.4.1.3 Settlement resistance factors for side resistance of drilled shafts in weak rock from uniaxial compression test measurements using approximate method.

Fig. 751.37.4.1.4 Settlement resistance factors for tip resistance of drilled shafts in weak rock from uniaxial compression test measurements using approximate method.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Weak Rock from Standard Penetration Test Measurements

Settlement resistance factors to be applied to side resistance for shaft segments through weak rock shall be determined from Figure 751.37.4.1.5 based on the coefficient of variation of the mean equivalent SPT N-value, $CO{V}_{\overline{N_{eq}}}$. Values for $CO{V}_{\overline{N_{eq}}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean equivalent N-value over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on weak rock shall similarly be determined from Figure 751.37.4.1.6 based on values for $CO{V}_{\overline{N_{eq}}}$ that reflect the variability of the mean equivalent N-value over the distance 2D_s below the tip of the shaft.

Fig. 751.37.4.1.5 Settlement resistance factors for side resistance of drilled shafts in weak rock from Standard Penetration Test measurements using approximate method.

Fig. 751.37.4.1.6 Settlement resistance factors for tip resistance of drilled shafts in weak rock from Standard Penetration Test measurements using approximate method.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Weak Rock from Texas Cone Penetration Test Measurements

Settlement resistance factors to be applied to side resistance for shaft segments through weak rock shall be determined from Figure 751.37.4.1.7 based on the coefficient of variation of the mean TCP-value, $CO{V}_{\overline{TCP}}$. Values for $CO{V}_{\overline{TCP}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean TCP-value over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on weak rock shall similarly be determined from Figure 751.37.4.1.8 based on values for $CO{V}_{\overline{TCP}}$ that reflect the variability of the mean TCP-value over the distance 2D_s below the tip of the shaft.

Fig. 751.37.4.1.7 Settlement resistance factors for side resistance of drilled shafts in weak rock from Texas Cone Penetration Test measurements using approximate method.

Fig. 751.37.4.1.8 Settlement resistance factors for tip resistance of drilled shafts in weak rock from Texas Cone Penetration Test measurements using approximate method.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Weak Rock from Point Load Index Test Measurements

Settlement resistance factors to be applied to side resistance for shaft segments through weak rock shall be determined from Figure 751.37.4.1.9 based on the coefficient of variation of the mean I_s(50)-value, $CO{V}_{\overline{I_{s(50)}}}$. Values for $CO{V}_{\overline{I_{s(50)}}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean I_s(50)-value for the rock over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on weak rock shall similarly be determined from Figure 751.37.4.1.10 based on values for $CO{V}_{\overline{I_{s(50)}}}$ that reflect the variability of the mean I_s(50)-value for the rock over the distance 2D_s below the tip of the shaft.

Fig. 751.37.4.1.9 Settlement resistance factors for side resistance of drilled shafts in weak rock from Point Load Index Test measurements using approximate method.

Fig. 751.37.4.1.10 Settlement resistance factors for tip resistance of drilled shafts in weak rock from Point Load Index Test measurements using approximate method.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Cohesive Soils

Settlement resistance factors to be applied to side resistance for shaft segments through cohesive soil shall be determined from Figure 751.37.4.1.11 based on the coefficient of variation of the mean undrained shear strength, $CO{V}_{\overline{s_u}}$. Values for $CO{V}_{\overline{s_u}}$ shall be determined in accordance with EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation to reflect the variability of the mean undrained shear strength for the soil over the shaft segment. Settlement resistance factors to be applied to tip resistance for shafts founded on cohesive soil shall similarly be determined from Figure 751.37.4.1.12 based on values for $CO{V}_{\overline{s_u}}$ that reflect the variability of the mean undrained shear strength for the soil over the distance 2D below the tip of the shaft.

Fig. 751.37.4.1.11 Settlement resistance factors for side resistance of drilled shafts in cohesive soil from undrained shear strength measurements using approximate method.

Fig. 751.37.4.1.12 Settlement resistance factors for tip resistance of drilled shafts in cohesive soil from undrained shear strength measurements using approximate method.

For shafts founded in soft cohesive soils, consideration shall also be given to including additional settlement induced from time dependent consolidation of the soil.

Settlement Resistance Factors for Approximate Method for Drilled Shafts in Cohesionless Soils

Settlement evaluations for individual drilled shafts in cohesionless soils shall be designed according to applicable sections of the current AASHTO LRFD Bridge Design Specifications.

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751.37.6.1 Reinforcement Design

Drilled shaft structural resistance shall be designed similarly to reinforced concrete columns. The Strength Limit State and applicable Extreme Event Limit State load combinations shall be used in the reinforcement design.

Longitudinal reinforcing steel shall extend below the point of fixity of the drilled shaft at least 10 ft. in accordance with LRFD 10.8.3.9.3 or the required bar development length whichever is larger.

If permanent casing is used, and the shell consists of a smooth pipe greater than 0.12 in. thick, it may be considered load carrying. An 1/8" shall be subtracted off of the shell thickness to account for corrosion. Casing could also be corrugated metal pipe. If casing is assumed to contribute to the structural resistance, the plans should indicate the minimum thickness of casing required.

Minimum clear spacing between longitudinal bars as well as between transverse bars shall not be less than five times the maximum aggregate size or 5 in. (LRFD 10.8.3.9.3).

For rock sockets use 3” min. clear cover. For drilled shafts for sign structure support, use 3” min. clear cover for all shaft diameters.

For longitudinal reinforcement, splicing shall be in accordance with LRFD 5.10.8.4.

For transverse reinforcement, lap splices for closed circular stirrups/ties shall be provided and staggered in accordance with LRFD 5.10.4.3. Lap length of 1.3 l_d (Class B) for closed stirrups/ties shall be provided in accordance with LRFD 5.10.8.2.6d.

For lap length, see EPG 751.5.9.2.8.1 Development and Lap Splice General.

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Commentary on EPG 751.37.1.3 Casing

Temporary or permanent casing is commonly required to support the shaft excavation during construction to prevent caving of overburden soils. Use of permanent casing generally simplifies construction by avoiding the need for multiple cranes to simultaneously place concrete and extract the casing and reduces the risk of problems during concrete placement. However, use of either temporary or permanent casing will generally reduce the side resistance of the constructed shaft over the cased length. Alternatives to use of casing for non-bridge structures include use of mineral or polymer slurry to maintain the stability of the excavation during construction, or use of no casing and no slurry when soil/rock conditions will permit the shafts to be constructed without caving of the excavation walls.

Permanent casing may also be required to provide structural resistance, especially when lateral loads are substantial (see EPG 751.37.6). For example, permanent casing may be required to:

• Achieve the required flexural resistance of the drilled shaft
• Resist large lateral loads for bridges located in seismic areas
• Facilitate shaft construction through water
• Support the shaft excavation when there is insufficient head room available for casing recovery

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751.38.1.1 Dimensions and Nomenclature

Dimensions to be established in design include the bearing depth (depth to footing base) and the footing dimensions shown in Figure 751.38.1.1. Table 751.38.1.1 defines each dimension and provides relevant minimum and/or maximum values for the respective dimension.

Fig. 751.38.1.1 Nomenclature used for spread footings.

Table 751.38.1.1 Summary of footing dimensions with minimum and maximum values

Dimension	Description	Minimum Value	Maximum Value	Comment
D	Column diameter	12”	--	--
B	Footing width	D+24”	--	Min. 3” increments
L	Footing length	D+24”1	--	Min. 3” increments
A	Edge distance in width direction	12”	--	--
A’	Edge distance in length direction	12”	--	--
t	Footing thickness	30” or D2	72”	Min. 3” increments
1 Minimum of 1/6 x distance from top of beam to bottom of footing
2 For column diameters ≥ 48”, use minimum value of 48”. Sign support structures may utilize a minimum thickness of 24”.

The nomenclature used in these guidelines has intentionally been selected to be consistent with that used in the AASHTO LRFD Bridge Design Specifications (AASHTO, 2009) to the extent possible to avoid potential confusion with methods provided in those specifications. By convention, references to other provisions of the MoDOT Engineering Policy Guide are indicated as “EPG XXX.XX” throughout these guidelines where the Xs are replaced with the appropriate article numbers. Similarly, references to provisions within the AASHTO LRFD Bridge Design Specifications are indicated as “LRFD XXX.XX”.

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751.38.1.2 General Design Considerations

Commentary for EPG 751.38.1.2 General Design Considerations

Footings shall be founded to bear a minimum of 36 in. below the finished elevation of the ground surface. In cases where scour, erosion, or undermining can be reasonably anticipated, footings shall bear a minimum of 36 in. below the maximum anticipated depth of scour, erosion, or undermining.

Footing size shall be proportioned so that stresses under the footing are as uniform as practical at the service limit state.

Long, narrow footings supporting individual columns should be avoided unless space constraints or eccentric loading dictate otherwise, especially on foundation material of low capacity. In general, spread footings should be made as close to square as possible. The length to width ratio of footings supporting individual columns should not exceed 2.0, except on structures where the ratio of longitudinal to transverse loads or site constraints makes use of such a limit impractical. For spread footings supporting overhead sign structures the length to width ratio of footings supporting individual columns may be as high as 4.0.

Footings located near to rock slopes (e.g. rock cuts, river bluffs, etc.) shall be located so that the footing is founded beyond a prohibited region established by a line inclined from the horizontal passing through the toe of the slope as shown in Figure 751.38.1.2. The boundary of the prohibited region shall be established by the Geotechnical Section. For the purposes of this provision, the toe of the slope shall be the point on the slope that produces the most severe location for the active zone. Exceptions to this provision shall only be made with specific approval of the Geotechnical Section and shall only be granted if overall stability can be demonstrated as provided in EPG 751.38.7.

Fig. 751.38.1.2 Prohibited region for spread footings placed near rock slopes unless exception is specifically approved by MoDOT Geotechnical Section.

Footings located near to soil slopes shall be evaluated for overall stability as provided in EPG 751.38.7 unless they are located a minimum distance of 2B beyond the crest of the slope.

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751.38.1.3 Related Provisions

The provisions in these guidelines were developed presuming that design parameters required to apply the provisions are established following current MoDOT site characterization protocols as described in EPG 321. Specific attention is drawn to EPG 321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation. The provisions provided in this subarticle presume that parameter variability, as generally represented by the coefficient of variation (COV), is established following procedures in EPG 321.3.

Sign structure spread footing supports are the exception. Sign structure standard spread footings are developed using assumed soil properties and following AASHTO LRFD Bridge Design Specifications 9^th Edition for design. Site specific designs for spread footings for sign structure support may also follow AASHTO LRFD Bridge Design Specifications 9^th Edition if there is not enough geotechnical information available to establish the COV.

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751.38.8.3 Details

Hooks at the end of reinforcement are not required for spread footings supporting sign structures. Include reinforcement near the top of spread footings supporting sign structures as required for uplift and in accordance with design requirements.

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G8. Drilled Shaft

(G8.1) Include underlined portion when a minimum thickness is required and shown on the plans as minimum.

Thickness of permanent steel casing shall be as shown on the plans and in accordance with Sec 701.

(G8.2) Note may not be required with drilled shafts for high mast tower lighting.

An additional 4 feet has been added to V-bar lengths and additional __-#_-P___ bars have been added in the quantities, if required, for possible change in drilled shaft or rock socket length. The additional V-bar length shall be cut off or included in the reinforcement lap if not required. The additional P bars shall be spaced similarly to that shown in elevation, if required, or to a lesser spacing if not required, but not less than 6-inch centers.

(G8.3) Note not required with drilled shafts for high mast tower lighting.

Sonic logging testing shall be performed on all drilled shafts and rock sockets.

(G8.4) Note to be used only with Drilled Shafts for High Mast Tower Lighting.

Drilling slurry, if used, shall require desanding.

(G8.5) Note to be used only with Drilled Shafts for High Mast Tower Lighting. Drilled shaft diameter is required to be at least 21 in. greater than the largest anticipated anchor bolt circle diameter per the DSP - High Mast Tower Lighting.

The following non-factored base reactions were used to design the drilled shafts for the       ft. high mast lighting towers: overturning moment = * kip-foot, base shear = * kip and axial force = * kip.

 *Values used in the design of the drilled shaft.

(G8.6) Use the following note only when the tops of drilled shafts are ≤ 3'-0" below the ground surface at centerline column / drilled shaft. Otherwise excavation quantity to the top of drilled shafts needs to be figured. Excavation diameter limit will be the 3'-0" larger than the column diameter above the drilled shaft.

The cost of any required excavation to the top of the drilled shafts will be considered completely covered by the contract unit price for other items.

(G8.7)

The tip of casing shall not extend into the rock socket elevation range reported in the Foundation Data table without approval by the engineer.

(G8.8) Use the following note when non-contact or contact lap is required at the top of drilled shaft between column/dowel reinforcement and drilled shaft reinforcement.

Column or dowel reinforcement shall be placed prior to pouring drilled shaft concrete in the area of the lap. Dowel bar or column reinforcement shall not be inserted after drilled shaft pour is complete.

(G8.9) For oversized shafts, use the following note in conjunction with callout for optional construction joint near top of drilled shaft.

Remove sediment laitance and weak concrete to sound concrete prior to setting column/dowel reinforcement if optional construction joint is used.

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Category:901 Lighting

Nonstandard Lighting Structures

If any lighting installation being considered will use a special or nonstandard structure or with dimensions exceeding those shown in the Standard Plans, Traffic should be consulted early in the project planning regarding the installation’s feasibility and necessary contract provisions. Examples of this situation are high mast lighting and exceeding lengths on the Standard Plans.

Since designing details for nonstandard installations is typically performed by an outside engineer employed by the contractor or producer and is certified to MoDOT, the project contract documents must include appropriate requirements about the design standards used. Since structures beyond MoDOT's standard designs are involved, a performance-based specification of the design signed and sealed by a Missouri Registered Professional Engineer is needed from the contractor. Certification to the current AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals including the latest fatigue provisions is required. For standard detailing notes regarding drilled shafts for High Mast Tower Lighting, see [[751.50_Standard_Detailing_Notes#G8._Drilled_Shaft|EPG 751.50 Standard Detailing Notes G8.4 and G8.5].

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901.7.6 High Mast Lighting

High mast lighting is principally used at complex interchanges and lights a large area by a group of luminaires mounted in a fixed orientation at the top of a tall mast, generally 80 ft. or taller. The district must authorize high mast lighting. The request for high mast lighting conceptual approval is to be included with the lighting warrants. Data supporting the selection of pole height, pole location and type of luminaires is to be included with the preliminary lighting plan. Where high mast lighting is used at complex interchanges, adaptation lighting is recommended for each section where vehicles enter and leave the interchange.

The district is responsible for all bid items associated with high mast lighting and to design the foundation and the structure above the foundation for inclusion in the project plans.

For standard detailing notes regarding drilled shafts for High Mast Tower Lighting, see [[751.50_Standard_Detailing_Notes#G8._Drilled_Shaft|EPG 751.50 Standard Detailing Notes G8.4 and G8.5].

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