Difference between revisions of "131.1 Design Exception Process"

From Engineering_Policy_Guide
Jump to navigation Jump to search
m (Updated Design Exception Info form by adding line for State Design Engineer's signature)
(16 intermediate revisions by 4 users not shown)
Line 3: Line 3:
 
|align-"center"|'''Forms'''
 
|align-"center"|'''Forms'''
 
|-style="background:#f5f5f5"
 
|-style="background:#f5f5f5"
|valign="top" align="center"| [[media:131.4 Design Exception Info 2013.doc|Design Exception Information Form]]
+
|valign="top" align="center"| [[media:131.1 Design Exception 2020.docx|Design Exception Information Form]]
 
|-
 
|-
|[http://ghepg01/forms/BR/Vertical%20Clearance%20Design%20Exception%20Coordination%20with%20SDDCTEA%20Form.doc Vertical Clearance Design Exception Coordination with SDDCTEA]
+
|[[media:131.1 Vertical Clearance Coord Form Jul 2018.pdf|Vertical Clearance Design Exception Coordination with SDDCTEA]]
 
|}
 
|}
  
==131.1.1  When to complete a design exception==
 
  
A design exception is encouraged wherever the potential for additional value lies outside of written engineering policy. They should not be considered breaches of policy as much as opportunities to add practicality to design.
+
==131.1.1 When to Complete a Design Exception==
  
Exceptions are not requests for permission; rather, they simply document deliberate variances from engineering policy. It is equally important to document those variances that exceed written standards as well as those that fail to attain them.  That is not to say a designer should attempt to exceed policy although such a course of action is, at times, the most practical solution.
+
A design exception documents design elements of an improvement that vary from engineering policy. In most cases the need for an exception results from an inability to reasonably meet the design criteria.
  
Documentation of a design exception is necessary for MoDOT to defend itself from litigation. Litigation may take place many years after the actual construction of an improvement.  Permanent documentation is necessary to determine the justification for the design exception.
+
An approved exception simply documents the engineering-based determination that variance from MoDOT’s engineering policy is necessary and appropriate. It is the primary tool to detail not only the decision itself, but also what was considered when the decision was made.  
  
A design exception consists of items that vary from preferred criteria for the design of an improvement.  In most cases the need for an exception is the result of an inability to reasonably meet the preferred design criteria.  However, there are occasions where specific design elements for a project may exceed the normal criteria recommended for the type of improvement.  These variations must also be documented through the design exception process.  When there is doubt if a design exception is required, the Design Division liaison engineer is to be consulted.
+
When there is doubt whether a design exception is required, the Assistant State Design Engineers, Assistant State Bridge Engineer or the Design Liaison Engineer (DLE) for the district should be consulted.  
  
==131.1.2  How to complete a design exception==
+
A design exception is encouraged whenever it is feasibly or technically impossible to reasonably meet the preferred design criteria or wherever there is potential for additional value outside of written engineering policy. Design exceptions should not be considered breaches of policy as much as opportunities to add practicality or value to the design.
  
When the need for a design exception has been identified, the appropriate person (listed below) is responsible for completing the standard [[media:131.4 Design Exception Info 2013.doc|Design Exception Information Form.]]  Use of this form is more effective official documentation than a casual notation.  The form must include a detailed description of the rationale for the change.
+
An approved exception is not a request for permission; rather, it simply documents deliberate variances from engineering policy.
  
After completion of the form, the order of approval by transportation officials, for each project category, is given below. A copy of every design exception is provided to the Design Division for the permanent project file.  A copy of the form is also kept in the district file.
+
==131.1.2 The 10 Controlling Criteria==
  
'''Full FHWA Oversight Projects''' (See [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|EPG 123.1.1 FHWA Oversight - National Highway System]])
+
There are 10 controlling criteria that the FHWA has identified as the most important or critical elements for the design of projects on the NHS. Projects designated for federal involvement on design exceptions in the PODI matrix, located on an NHS Route, require a MoDOT and FHWA approved written design exception if a controlling criteria, as established in MoDOT’s EPG, is not met for any of the 10 elements listed in Table 131.1.2.
# district project manager
 
# district engineer
 
# State Design and/or State Bridge Engineer
 
# FHWA
 
'''Exempt Roadway Projects'''
 
# district project manager
 
# district engineer
 
'''Exempt Bridge Projects'''
 
# district project manager
 
# district engineer
 
# State Bridge Engineer
 
'''Consultant Designed or Cost Share Projects'''
 
# consultant or local public agency
 
# appropriate project-specific path shown above
 
  
 +
The controlling criteria, which vary based upon the type of route and design speed, are described below:
  
The Federal Highway Administration (FHWA) reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight.
+
<center>'''Table 131.1.2 Controlling Criteria'''
 +
{| style="margin: 1em auto 1em auto"
 +
|-
 +
! style="background:#BEBEBE" |NHS with Design Speed > 50 mph!!width="25"| !! style="background:#BEBEBE" |NHS with Design Speed < 50 mph !! width="25"| !!style="background:#BEBEBE" |Non-NHS
 +
|-
 +
|Design Speed|| ||Design Speed|| || (No Controlling Criteria)
 +
|-
 +
|Design Loading Structural Capacity|| ||Design Loading Structural Capacity ||
 +
|-
 +
|Lane Width||
 +
|-
 +
|Shoulder Width ||
 +
|-
 +
|Horizontal Curve Radius||
 +
|-
 +
|Superelevation Rate||
 +
|-
 +
|Stopping Sight Distance||
 +
|-
 +
|Maximum Grade||
 +
|-
 +
|Cross Slope||
 +
|-
 +
|Vertical Clearance||
 +
|}
 +
 
 +
</center>
 +
A MoDOT (only) approved design exception is required for all other non -complying design elements on projects which are designated for federal involvement for design exceptions and for all non-complying design elements on all of other projects  not designated for federal involvement for design exceptions.
 +
 
 +
==131.1.3 Approval Requirements==
 +
 
 +
<center>'''Table 131.1.3 Design Exception Required Approvals'''
 +
 
 +
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
 +
|+
 +
! style="background:#BEBEBE" |Category!! style="background:#BEBEBE" |PODI Designated !! style="background:#BEBEBE" |Controlling Criteria'''*'''!! style="background:#BEBEBE" |FHWA!! style="background:#BEBEBE"|MoDOT
 +
|-
 +
|rowspan="3"|'''NHS'''||rowspan="2"|Yes||Yes||✓|| ✓
 +
|-
 +
|No|| ||✓
 +
|-
 +
|No||Yes or No|| ||✓
 +
|-
 +
|'''Non-NHS'''||Yes or No||N/A|| ||✓
 +
|-
 +
|align="left" colspan="5"|'''*''' Applicable Controlling Criteria as indicated in EPG 131.1.2.
 +
|}
 +
</center>
 +
 
 +
 
 +
===131.1.3.1 Projects of Divisional Interest (PODI)===
 +
 
 +
 
 +
See [http://epg.modot.org/index.php?title=Category:123_Federal-Aid_Highway_Program#123.1.1_FHWA_Oversight_-_National_Highway_System EPG 123.1.1 FHWA Oversight - National Highway System] for information on federal involvement on projects and for the PODI matrix. 
 +
 
 +
==131.1.4 The Design Exception Process==
 +
 
 +
Requests for design exceptions are submitted when the need first arises; however, they may be submitted at any time and specifically along with the [[:Category:128 Conceptual Studies|conceptual study]], [[:Category:235 Preliminary Plans|preliminary plan]], right of way certification, or plans, specifications, and estimate (PS&E).  In general, it is best to identify and consider the design exception as early as practical in the design process.
 +
 
 +
When the need for a design exception has been identified, the project manager, Structural Project Manager or consultant representative is responsible for completing the standard [[media:131.1 Design Exception 2020.docx|Design Exception Information Form]]. The form must include a detailed description of the rationale for the change and the appropriate supporting documentation to satisfactorily justify the decision and document any mitigation efforts associated with varying from the engineering policy. Examples of approved Design Exceptions can be found here<provide link>. (Please note that previous approval of an item should not be considered approval of the item on any future project. Approval for future projects must be sought on a case-by-case basis.)
 +
 
 +
Project managers (consultant, transportation or bridge) and their design staff should recognize the importance of an open and transparent decision making process while considering the suitability and appropriateness of a given design element that is not consistent with our current policies.  Since our engineering policy is established through a collaborative effort, it is critical to engage all appropriate staff when making the decision not to meet our policies.  While completing the form, communication with the appropriate staff, including the Design Liaison Engineer, a representative of any affected MoDOT division and FHWA (when applicable), is critical to ensure efficient and effective review and approval.  For efficient processing and to avoid delays, this communication should occur prior to the formal submittal.  Depending upon the item being excepted and the type of project, the appropriate review staff and signatory parties will vary. 
 +
<div id="A copy of every fully approved"></div>
 +
 
 +
Central Office staff should be consulted and provide review of the draft design exception prior to district approval.  A link to the electronic copy of every fully approved design exception is provided to the [http://sharepoint/sites/de/Pages/default.aspx Central Office Design Division] and [http://sharepoint/systemdelivery/br/Pages/default.aspx Central Office Bridge Division], as appropriate.  A final copy of the design exception is saved in [http://eprojects/SitePages/Home.aspx eProjects] using the appropriate content type: DE Letting Documents.  Staff should include any pertinent information in the Comments Section within eProjects. 
 +
 
 +
PODI design exceptions are processed through the Design Liaisons for the State Design Engineer and FHWA signatures of approval.  The Design Liaisons provide the electronic copy of the fully approved design exception back to the PM for placement in eProjects. 
 +
 
 +
It should be noted that the Federal Highway Administration (FHWA) reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight.
 +
 
 +
===131.1.4.1 The Development, Concurrence and Approval Process===
 +
 
 +
In addition to the applicable process requirements described below, vertical clearance design exceptions on the interstate must also follow the additional requirement described in [[#131.1.7 Deficient Vertical Clearances on Interstates|EPG 131.1.7 Deficient Vertical Clearances on Interstates]].
 +
 
 +
====131.1.4.1.1 Roadway Design Exceptions====
 +
Upon the core team's determination that a design exception is warranted, the following process should be used for design exception submittals relating to roadway items only:
 +
 
 +
'''Conceptual Approval:'''
 +
 
 +
:1) The Transportation Project Manager (TPM) working with the Consultant Project Manager, if applicable, submits the design exception form, submittal letter and supporting information to the Design Liaison Engineer (DLE), the District Design Engineer (DDE), FHWA (if applicable) and any other pertinent district and division staff.
 +
 
 +
:2) The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue.
 +
 
 +
:3) The TPM works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.
 +
 
 +
:4) The TPM submits the design exception for signature according to flowchart below.
 +
 
 +
'''Formal Approval: '''
 +
 
 +
Signatures for approval should be obtained in accordance with the following flowchart:
 +
 
 +
[[image:131.1.4.1.1 2015.jpg|center|650px|thumb|<center>'''Route as appropriate to obtain approvals in the appropriate order.'''</center><br/>'''*''' Note: Concurrence only if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.<br/>'''**''' Note: Omitted if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix. ]]
 +
 
 +
 
 +
====131.1.4.1.2 Bridge Design Exceptions====
 +
The following process should be used for design exception submittals relating to bridge items:
 +
 
 +
'''Conceptual Approval:'''
 +
 
 +
:1. The Structural Project Manager (SPM), or the Structural Liaison Engineer (SLE) working with the Consultant Project Manager submits the design exception form, submittal letter and supporting information to the Assistant State Bridge Engineer, the Design Liaison Engineer (DLE), the Transportation Project Manager, FHWA (if applicable) and any other pertinent district and division staff.
 +
 
 +
:2. The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue (if significant objection is determined).
 +
 
 +
:3. The SPM/SLE works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.  
  
The request for travelway design exceptions must be initiated and signed by the project manager in charge of the project. The project manager will submit the design exception information form to the district engineer and following approval to the Design Division as necessary.
+
:4. The SPM/SLE submits the design exception for signature according to the flowchart below.
  
If a consultant is designing the project, their project manager will initiate the request and sign the design exception form first and then submit it to the district project manager.  All consultant design exceptions are reviewed by the district and signed by the district's project manager prior to submittal to the district engineer and following approval to the Design Division as necessary.
+
'''Formal Approval:'''
  
Design exceptions that contain only bridge related items are initiated by the Bridge Division and should adhere to the following process:
+
Signatures for approval should be obtained in accordance with the following flowchart:
  
:'''1'''. The Bridge Division prepares the design exception information form.
+
[[image:131.1.4.1.2 2015.jpg|center|600px|thumb|<center>'''Route as appropriate to obtain approvals in the appropriate order.'''</center><br/>'''*''' Note: Concurrence only if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.<br/>'''**''' Note: Omitted if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix. ]]
  
:'''2'''. The design exception is reviewed and/or approved by the State Bridge Engineer.
 
  
:'''3'''. The structural project manager transmits the signed design exception information form to the district project manager for review and signature.
+
====131.1.4.1.3 Both Roadway and Bridge Item Related Design Exceptions====
 +
Occasionally, both roadway and bridge items will need to be included. In these instances, the TPM and the SLE/SLM should agree to a single point of contact for the review, concurrence and approval of the design exception and will ensure that the appropriate staff members are properly engaged throughout the process.
  
:'''4'''. The district project manager will submit the design exception information form to the district engineer and the Design Division as necessary for final processing.
+
===131.1.4.2 Issue Resolution===
  
:'''5'''. The Design Division will be responsible for obtaining approval signatures as necessary and furnish the district and the Bridge Division with copies of the final approved document.
+
The review and concurrence process is intended to avoid any significant objections, questions or concerns during the approval process, however, occasionally these issues may arise. In this instance, the design exception approval process may be put on hold until the issue can be resolved by the appropriate staff members.  The TPM or SLE/SLM will remain the primary contact to address any request for additional information or consideration.
  
Design exceptions that contain both travelway and bridge related items will adhere to the following process:
+
===131.1.4.3 Design Exception Numbering and Logging===
  
:'''1'''. The Bridge Division completes the information related to the bridge items on the design exception form.   
+
As design exceptions serve as the permanent record of the design decision, providing a design exception numbering and logging system will benefit tracking the submittal and return of each exception and to ensure that all design exceptions are acknowledged and accounted for. The preferred design exception numbering system is the job number followed by a sequential number for each design exception.  For example, the first roadway design exception for project JXPXXXX would be Design Exception (DE) # JXPXXXX-R1.  The second would be JXPXXXX-R2, and so forth.  The first bridge design exception for project JXPXXXX would be DE# JXPXXXX-B1.  If a design exception includes both roadway and bridge items, it will be numbered and logged according to who initiates the design exception.  The logging system in each project file should indicate the design exception number and the date submitted and date received.  If a design exception is not approved, the number should be recorded and noted that it was not approved.  The next design exception would be numbered with the next available number.  Additionally, as a best management practice, the design exception log and the design exceptions themselves may be located in the project file or a project SharePoint site.
  
:'''2'''. The structural project manager will transmit, electronically if possible, the design exception information form to the district project manager for review.
+
==131.1.5 Required Information==
  
:'''3'''. The district project manager will add the information related to the travelway items and sign the form.
+
Whenever the engineering policy cannot be met, data for only those non-standard items is listed. This data includes a brief description of the project and the improvement goals that are being attempted. This information is required since the context of the project often helps in deciding if approval of the exception is appropriate. Additionally, the data should include the details related to the existing feature (if applicable), the desired design criteria for that feature, the proposed solution, and the location (limits) associated with the solution. The column shown for existing features is not applicable to new construction. The appropriate values for desired design criteria are shown in the second column. The design criteria for new construction on rural and urban highways are stated in individual articles pertaining to each geometric element discussed in the [[:Category:200 GEOMETRICS|EPG 200 Geometrics]] articles. Design criteria for 3R and 4R projects are discussed in [[:Category:128 Conceptual Studies|EPG 128 Conceptual Studies]]. The criteria for proper access management can be found in [[:Category:940 Access Management|EPG Access Management]].  
  
:'''4'''. The district project manager will submit the design exception information form to the district engineer and the Design Division as necessary for final processing. This will include signature by the State Bridge Engineer and the State Design Engineer.
+
All design exceptions must suitably explain the justification for the exception. It is imperative that this justification be sufficiently complete to clearly reflect that the designer exercised reasonable care in the selection of a particular highway design. Design exceptions  often arise because it is impractical or impossible to reasonably meet engineering policy. The justification may include appropriate economic analysis, discussion of applicable accident location and type or discussion of avoidance of [[127.10 Section 4(f) Public Lands#127.10.2.1.1 Section 4(f) Properties|Section 4(f)]] or [[127.10 Section 4(f) Public Lands#127.10.2.1.2 Section 6(f) Properties|Section 6(f)]] lands. The justification supports the concept that maximum service and safety benefits were realized for the cost invested. Engineering judgment is used when balancing the economic and engineering reasons for the justification. A design exception is based on sound engineering judgment rather than being solely an attempt to save cost.
  
:'''5'''. The Design Division will be responsible for obtaining approval signatures as necessary and will furnish the district and the Bridge Division with copies of the final approved document.
+
In general all design exceptions should include the following:
  
Requests for [[media:131.4 Design Exception Info 2013.doc|design exceptions]] are made when the need first arises; specifically at submittal of the conceptual study, preliminary plan, right of way certification, or plans, specifications, and estimate (PS&E).
+
:* Specific design criteria that will not be met.
 +
:* Existing roadway characteristics.
 +
:* Alternatives considered.
 +
:* Comparison of the safety and operational performance of the roadway and other impacts such as right-of-way, community, environmental, cost, and usability by all modes of transportation.
 +
:* Proposed mitigation measures.
 +
:* Compatibility with adjacent sections of roadway.
  
Whenever desired design criteria cannot be met, data for only those non-standard items is listed.  This data includes the existing feature (if applicable), the desired design criteria for that feature, the proposed feature, and the location of the feature.  The column shown for existing features is not applicable to new construction.  The appropriate values for desired design criteria are shown in the second column.  The design criteria for new construction on rural and urban highways are stated in individual articles pertaining to each geometric element discussed in the [[:Category:200 GEOMETRICS|EPG 200 Geometrics]] articles.  Design criteria for [[:Category:128 Conceptual Studies#128.3 Pavement Rehabilition Projects - Non - Freeway Roadways|3R]] and [[:Category:128 Conceptual Studies#128.4 Pavement Rehabilition Projects for Freeways|4R]] projects are discussed in EPG 128.  The criteria for proper access management can be found in MoDOT’s [[:Category:940 Access Management|Access Management Guidelines]].  A Design Exception Information Form is not required if all desired design criteria are used for the improvement project.
+
Note: The level of analysis should be commensurate with the complexity of the project.
  
All requests must contain reasons to justify the exceptions.  It is imperative that the justification be sufficiently complete to clearly reflect that the designer exercised reasonable care in the selection of a particular highway design.  It must be kept in mind when writing the justification that design exceptions arise because it is impractical or impossible to reasonably meet a specific design criteria.  If the criteria can be reasonably met, then the item in question is built to the criteria.  The justification may include appropriate economic analysis, discussion of applicable accident location and type or discussion of avoidance of [[127.10 Section 4(f) Public Lands#127.10.2.1.1 Section 4(f) Properties|Section 4(f)]] or [[127.10 Section 4(f) Public Lands#127.10.2.1.2 Section 6(f) Properties|Section 6(f)]] lands.  The justification supports the concept that maximum service and safety benefits were realized for the cost invested.  Engineering judgment is used when balancing the economic and engineering reasons for the justification.  A design exception is based on sound engineering judgment rather than an attempt to save cost.
+
In addition to the information above, exceptions for the Design Speed and Design Loading Structural Capacity criteria should include the following information;
<div id="If the design exception request"></div>
 
  
If the design exception request involves any features that are safety related, then sufficient accident data and history is attached to the request to support the reasons for justification.  A summary report of the accident information is acceptable if the volume of the data is excessive.  Examples of safety related features are included in, but not limited to, the following list: lane width, shoulder width, shoulder type, rumble strips, turn lanes, bridge width, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance,
+
Design Speed exceptions:
guardrail, etc. Any other items that may be perceived as a safety concern will also follow these requirements.
+
:* Length of section with reduced design speed compared to overall length of project
 +
:* Measures used in transitions to adjacent sections with higher or lower design or operating speeds.
  
In addition, if the design exception request involves safety related features that are adequately addressed in the AASHTO ''Highway Safety Manual'', then documentation of the exception should include a safety analysis as described in the manual. In general, this safety analysis should compare the expected number of crashes for the facility with the design exception to the expected number of crashes of the facility without the design exception. Currently, not all safety related features are explicitly addressed in the ''Highway Safety Manual''. A list of features currently addressed by the manual include: lane width, shoulder width, shoulder type, center line rumble strips, horizontal alignment (length, radius), grade, roadside hazard rating, fixed objects, driveway density, median width, sideslope, lighting, intersection skew angle and turn lanes. Not all features in the manual are addressed for each facility type.
+
Design Loading Structural Capacity exceptions:
 +
:* Verification of safe load-carrying capacity (load rating) for all state unrestricted legal loads or routine permit loads, and in the case of bridges and tunnels on the interstate, all federal legal loads.
  
A transmittal letter that describes the nature of the exceptions that are requested will accompany each design exception request.  This letter will also include a brief description of the purpose and need of the project and the improvement goals that it is intended to accomplish.  This information is required since the context of the project often helps in deciding if the exception is to be approved.
+
'''Safety related features'''
  
All exception requests for [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|"non-exempt"]] projects (interstate in excess of $5 million, NHS projects in excess of $20 million and all bridges with any span length of 500 ft. or more, see [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|EPG 123.1.1]]) are submitted to the Design Division for approval, where the design liaison engineer reviews and forwards them to the State Design Engineer.  After approval by the State Design Engineer (State Traffic Engineer for access management items or the State Bridge Engineer for bridge items), the design liaison engineer will provide the information to the FHWA for their approval. Once approved by the FHWA the design liaison engineer will provide a copy of the signed exception to the district and/or other affected divisions at the Central Office.
+
If the design exception request involves any features that are safety related, then sufficient crash data and history is attached to the request to support the reasons for justification. A summary report of the crash information is acceptable if the volume of the data is excessive. Examples of safety related features include, but not limited to, the following: design speed, stopping sight distance, passing sight distance, lane width, shoulder width, shoulder type, rumble strips, turn lanes, bridge width, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance, guardrail, etc.  Any other items that may be perceived as a safety concern will also follow these requirements.
  
Exception requests for "exempt" projects (all other projects) do not require direct federal oversight and therefore will not require FHWA approval.  For these projects where a design exception is required the district engineer has final approval authority.  However, the district must submit a copy of the approved design exception to the Design Division.
+
In addition, if the design exception request involves safety related features that are adequately addressed in the AASHTO ''Highway Safety Manual'', then documentation of the exception should include a safety analysis as described in the manual. Typically, this process will involve two primary determinations:
 +
*Calculate the expected change in crashes from existing conditions to standard design conditions
 +
*Calculate the expected change in crashes from existing conditions to the proposed design.
  
Changes in project scope or design criteria can result in changes to design exceptions that have previously been considered.  There may also be additional features that were not included on an earlier exception request that now requires approval. In these cases, an [[media:131.4 Design Exception Info 2013.doc|amended Design Exception Information Form]] must be completed and approved (as described above).  The amended form should include all exceptions previously approved in addition to the new features.  The transmittal letter will include sufficient information to indicate the items that have received prior design exception approval.
+
The proposed design should take into account any design exceptions as well as any additional safety features above and beyond the standard design.  
  
The Design Division maintains the design exceptions in a permanent project file. A copy of the form is also kept in the district file and any other affected Central Office divisions.
+
By making these two determinations, a quantitative safety comparison can be made between existing conditions, the standard design, and the proposed design. This information, along with other project considerations, can be used to help determine the best design alternative. A list of features currently addressed by the manual include: lane width, shoulder width, shoulder type, center line rumble strips, horizontal alignment (length, radius), grade, roadside hazard rating, fixed objects, driveway density, median width, sideslope, lighting, intersection skew angle and turn lanes. Not all features in the manual are addressed for each facility type.
  
==131.1.3 Deficient Vertical Clearances on Interstates==
+
===131.1.6 Revising an Approved Design Exception ===
  
Maintaining the integrity of interstates for national defense purposes has long been recognizedInterstates are intended to be constructed and maintained to meet AASHTO Policy as stated in ''A Policy on Design Standards - Interstate System'', which is incorporated by reference in [http://www.fhwa.dot.gov/legsregs/directives/fapg/cfr0625.htm 23 CFR 625].  Maintaining standard vertical clearances to the extent possible for defense mobilization is considered particularly important and is a focus at the national level.   As a result, the [http://www.fhwa.dot.gov/ FHWA] has agreed that all exceptions to a 16 ft. vertical clearance standard for the rural interstate and certain single routings on the urban interstates be coordinated with the [http://www.tea.army.mil/ Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA)] of the Department of Defense.  This agreement applies whether it is a new construction project, a project that does not provide for the correction of an existing substandard condition, or a project that creates a substandard condition at an existing structure. The steps involved are:   
+
Changes in project scope or design criteria can result in changes to design exceptions that have previously been consideredIn these cases, a revised design exception must be completed and approved (as described above).  The original design exception should accompany the revised information in order to illustrate the changes. The transmittal letter should address the changes and an explanation of the circumstances leading to the revision.  
  
-  For a vertical clearance over any interstate highway that will be less than 16 ft. meeting the above criteria, the district submits to the [http://wwwi/design/default.htm Design Division] a completed SDDCTEA Interstate Vertical Clearance Coordination Form along with a Design Exception for vertical clearance.
+
==131.1.7 Deficient Vertical Clearances on Interstates==
  
- The Design Liaison Engineer emails the Bridge Inventory Analysts and requests the Structure NBI number for box 2 on the Vertical Clearance Design Exception Coordination with SDDCTEA Form.
+
Maintaining the integrity of interstates for national defense purposes has long been recognized. Interstates are intended to be constructed and maintained to meet AASHTO Policy as stated in ''A Policy on Design Standards - Interstate System'', which is incorporated by reference in [http://www.fhwa.dot.gov/legsregs/directives/fapg/cfr0625.htm 23 CFR 625].  Maintaining standard vertical clearances to the extent possible for defense mobilization is considered particularly important and is a focus at the national level.  As a result, the [http://www.fhwa.dot.gov/ FHWA] has agreed that all exceptions to a 16 ft. vertical clearance standard for the rural interstate and certain single routings on the urban interstates be coordinated with the Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA) of the Department of Defense. This coordination applies whether it is a new construction project, a project that does not provide for the correction of an existing substandard condition, or a project that creates a substandard condition at an existing structure. The steps involved are:   
  
-  The Design Liaison Engineer submits the Design Exception for full oversight projects to FHWA. If the project does not require full FHWA oversight, the Design Liaison routes the Design Exception for the necessary internal MoDOT signatures.  
+
:1. For a vertical clearance over any interstate highway that will be less than 16 ft. meeting the above criteria, the district submits to the [http://wwwi/design/default.htm Design Division] a completed SDDCTEA Interstate Vertical Clearance Coordination Form along with a Design Exception for vertical clearance.
 
 
-  Concurrent with the submission or routing of the Design Exception, the Design Liaison Engineer submits the form to the SDDCTEA and copies FHWA.  This may be done electronically using the contact information on the [http://ghepg01/forms/BR/Vertical%20Clearance%20Design%20Exception%20Coordination%20with%20SDDCTEA%20Form.doc Vertical Clearance Design Exception Coordination with SDDCTEA].
 
  
- A response from SDDCTEA should occur within 10 working days following receipt of the coordination request.  Receipt of the request can be verified with SDDCTEA via telephone or fax.  If there is no response after 10 working days following receipt, it can be determined that SDDCTEA does not have any concerns about the proposed exception.
+
:2 The Design Liaison Engineer emails the Bridge Inventory Analysts and requests the Structure NBI number for box 2 on the Vertical Clearance Design Exception Coordination with SDDCTEA Form.
  
-  The Design Liaison Engineer informs FHWA as to the final outcome of the SDDCTEA request.
+
:3. Concurrent with the submission or routing of the Design Exception, the Design Liaison Engineer submits the form to the SDDCTEA and copies FHWA.  This may be done electronically using the contact information on the [[media:131.1 Vertical Clearance Coord Form Jul 2018.pdf|Vertical Clearance Design Exception Coordination with SDDCTEA]].
  
 +
:4. A response from SDDCTEA should occur within 10 working days following receipt of the coordination request. Receipt of the request can be verified with SDDCTEA via telephone or fax. If there is no response after 10 working days following receipt, it can be determined that SDDCTEA does not have any concerns about the proposed exception.
  
 +
:5. The Design Liaison Engineer informs FHWA as to the final outcome of the SDDCTEA request. 
  
 
[[category:131 Other General Procedures|131.01]]
 
[[category:131 Other General Procedures|131.01]]

Revision as of 09:08, 18 November 2020

Forms
Design Exception Information Form
Vertical Clearance Design Exception Coordination with SDDCTEA


131.1.1 When to Complete a Design Exception

A design exception documents design elements of an improvement that vary from engineering policy. In most cases the need for an exception results from an inability to reasonably meet the design criteria.

An approved exception simply documents the engineering-based determination that variance from MoDOT’s engineering policy is necessary and appropriate. It is the primary tool to detail not only the decision itself, but also what was considered when the decision was made.

When there is doubt whether a design exception is required, the Assistant State Design Engineers, Assistant State Bridge Engineer or the Design Liaison Engineer (DLE) for the district should be consulted.

A design exception is encouraged whenever it is feasibly or technically impossible to reasonably meet the preferred design criteria or wherever there is potential for additional value outside of written engineering policy. Design exceptions should not be considered breaches of policy as much as opportunities to add practicality or value to the design.

An approved exception is not a request for permission; rather, it simply documents deliberate variances from engineering policy.

131.1.2 The 10 Controlling Criteria

There are 10 controlling criteria that the FHWA has identified as the most important or critical elements for the design of projects on the NHS. Projects designated for federal involvement on design exceptions in the PODI matrix, located on an NHS Route, require a MoDOT and FHWA approved written design exception if a controlling criteria, as established in MoDOT’s EPG, is not met for any of the 10 elements listed in Table 131.1.2.

The controlling criteria, which vary based upon the type of route and design speed, are described below:

Table 131.1.2 Controlling Criteria
NHS with Design Speed > 50 mph NHS with Design Speed < 50 mph Non-NHS
Design Speed Design Speed (No Controlling Criteria)
Design Loading Structural Capacity Design Loading Structural Capacity
Lane Width
Shoulder Width
Horizontal Curve Radius
Superelevation Rate
Stopping Sight Distance
Maximum Grade
Cross Slope
Vertical Clearance

A MoDOT (only) approved design exception is required for all other non -complying design elements on projects which are designated for federal involvement for design exceptions and for all non-complying design elements on all of other projects not designated for federal involvement for design exceptions.

131.1.3 Approval Requirements

Table 131.1.3 Design Exception Required Approvals
Category PODI Designated Controlling Criteria* FHWA MoDOT
NHS Yes Yes
No
No Yes or No
Non-NHS Yes or No N/A
* Applicable Controlling Criteria as indicated in EPG 131.1.2.


131.1.3.1 Projects of Divisional Interest (PODI)

See EPG 123.1.1 FHWA Oversight - National Highway System for information on federal involvement on projects and for the PODI matrix.

131.1.4 The Design Exception Process

Requests for design exceptions are submitted when the need first arises; however, they may be submitted at any time and specifically along with the conceptual study, preliminary plan, right of way certification, or plans, specifications, and estimate (PS&E). In general, it is best to identify and consider the design exception as early as practical in the design process.

When the need for a design exception has been identified, the project manager, Structural Project Manager or consultant representative is responsible for completing the standard Design Exception Information Form. The form must include a detailed description of the rationale for the change and the appropriate supporting documentation to satisfactorily justify the decision and document any mitigation efforts associated with varying from the engineering policy. Examples of approved Design Exceptions can be found here<provide link>. (Please note that previous approval of an item should not be considered approval of the item on any future project. Approval for future projects must be sought on a case-by-case basis.)

Project managers (consultant, transportation or bridge) and their design staff should recognize the importance of an open and transparent decision making process while considering the suitability and appropriateness of a given design element that is not consistent with our current policies. Since our engineering policy is established through a collaborative effort, it is critical to engage all appropriate staff when making the decision not to meet our policies. While completing the form, communication with the appropriate staff, including the Design Liaison Engineer, a representative of any affected MoDOT division and FHWA (when applicable), is critical to ensure efficient and effective review and approval. For efficient processing and to avoid delays, this communication should occur prior to the formal submittal. Depending upon the item being excepted and the type of project, the appropriate review staff and signatory parties will vary.

Central Office staff should be consulted and provide review of the draft design exception prior to district approval. A link to the electronic copy of every fully approved design exception is provided to the Central Office Design Division and Central Office Bridge Division, as appropriate. A final copy of the design exception is saved in eProjects using the appropriate content type: DE Letting Documents. Staff should include any pertinent information in the Comments Section within eProjects.

PODI design exceptions are processed through the Design Liaisons for the State Design Engineer and FHWA signatures of approval. The Design Liaisons provide the electronic copy of the fully approved design exception back to the PM for placement in eProjects.

It should be noted that the Federal Highway Administration (FHWA) reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight.

131.1.4.1 The Development, Concurrence and Approval Process

In addition to the applicable process requirements described below, vertical clearance design exceptions on the interstate must also follow the additional requirement described in EPG 131.1.7 Deficient Vertical Clearances on Interstates.

131.1.4.1.1 Roadway Design Exceptions

Upon the core team's determination that a design exception is warranted, the following process should be used for design exception submittals relating to roadway items only:

Conceptual Approval:

1) The Transportation Project Manager (TPM) working with the Consultant Project Manager, if applicable, submits the design exception form, submittal letter and supporting information to the Design Liaison Engineer (DLE), the District Design Engineer (DDE), FHWA (if applicable) and any other pertinent district and division staff.
2) The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue.
3) The TPM works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.
4) The TPM submits the design exception for signature according to flowchart below.

Formal Approval:

Signatures for approval should be obtained in accordance with the following flowchart:

Route as appropriate to obtain approvals in the appropriate order.

* Note: Concurrence only if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.
** Note: Omitted if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.


131.1.4.1.2 Bridge Design Exceptions

The following process should be used for design exception submittals relating to bridge items:

Conceptual Approval:

1. The Structural Project Manager (SPM), or the Structural Liaison Engineer (SLE) working with the Consultant Project Manager submits the design exception form, submittal letter and supporting information to the Assistant State Bridge Engineer, the Design Liaison Engineer (DLE), the Transportation Project Manager, FHWA (if applicable) and any other pertinent district and division staff.
2. The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue (if significant objection is determined).
3. The SPM/SLE works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.
4. The SPM/SLE submits the design exception for signature according to the flowchart below.

Formal Approval:

Signatures for approval should be obtained in accordance with the following flowchart:

Route as appropriate to obtain approvals in the appropriate order.

* Note: Concurrence only if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.
** Note: Omitted if not indicated that federal approval is required in accordance with EPG 131.1.3 and the PODI matrix.


131.1.4.1.3 Both Roadway and Bridge Item Related Design Exceptions

Occasionally, both roadway and bridge items will need to be included. In these instances, the TPM and the SLE/SLM should agree to a single point of contact for the review, concurrence and approval of the design exception and will ensure that the appropriate staff members are properly engaged throughout the process.

131.1.4.2 Issue Resolution

The review and concurrence process is intended to avoid any significant objections, questions or concerns during the approval process, however, occasionally these issues may arise. In this instance, the design exception approval process may be put on hold until the issue can be resolved by the appropriate staff members. The TPM or SLE/SLM will remain the primary contact to address any request for additional information or consideration.

131.1.4.3 Design Exception Numbering and Logging

As design exceptions serve as the permanent record of the design decision, providing a design exception numbering and logging system will benefit tracking the submittal and return of each exception and to ensure that all design exceptions are acknowledged and accounted for. The preferred design exception numbering system is the job number followed by a sequential number for each design exception. For example, the first roadway design exception for project JXPXXXX would be Design Exception (DE) # JXPXXXX-R1. The second would be JXPXXXX-R2, and so forth. The first bridge design exception for project JXPXXXX would be DE# JXPXXXX-B1. If a design exception includes both roadway and bridge items, it will be numbered and logged according to who initiates the design exception. The logging system in each project file should indicate the design exception number and the date submitted and date received. If a design exception is not approved, the number should be recorded and noted that it was not approved. The next design exception would be numbered with the next available number. Additionally, as a best management practice, the design exception log and the design exceptions themselves may be located in the project file or a project SharePoint site.

131.1.5 Required Information

Whenever the engineering policy cannot be met, data for only those non-standard items is listed. This data includes a brief description of the project and the improvement goals that are being attempted. This information is required since the context of the project often helps in deciding if approval of the exception is appropriate. Additionally, the data should include the details related to the existing feature (if applicable), the desired design criteria for that feature, the proposed solution, and the location (limits) associated with the solution. The column shown for existing features is not applicable to new construction. The appropriate values for desired design criteria are shown in the second column. The design criteria for new construction on rural and urban highways are stated in individual articles pertaining to each geometric element discussed in the EPG 200 Geometrics articles. Design criteria for 3R and 4R projects are discussed in EPG 128 Conceptual Studies. The criteria for proper access management can be found in EPG Access Management.

All design exceptions must suitably explain the justification for the exception. It is imperative that this justification be sufficiently complete to clearly reflect that the designer exercised reasonable care in the selection of a particular highway design. Design exceptions often arise because it is impractical or impossible to reasonably meet engineering policy. The justification may include appropriate economic analysis, discussion of applicable accident location and type or discussion of avoidance of Section 4(f) or Section 6(f) lands. The justification supports the concept that maximum service and safety benefits were realized for the cost invested. Engineering judgment is used when balancing the economic and engineering reasons for the justification. A design exception is based on sound engineering judgment rather than being solely an attempt to save cost.

In general all design exceptions should include the following:

  • Specific design criteria that will not be met.
  • Existing roadway characteristics.
  • Alternatives considered.
  • Comparison of the safety and operational performance of the roadway and other impacts such as right-of-way, community, environmental, cost, and usability by all modes of transportation.
  • Proposed mitigation measures.
  • Compatibility with adjacent sections of roadway.

Note: The level of analysis should be commensurate with the complexity of the project.

In addition to the information above, exceptions for the Design Speed and Design Loading Structural Capacity criteria should include the following information;

Design Speed exceptions:

  • Length of section with reduced design speed compared to overall length of project
  • Measures used in transitions to adjacent sections with higher or lower design or operating speeds.

Design Loading Structural Capacity exceptions:

  • Verification of safe load-carrying capacity (load rating) for all state unrestricted legal loads or routine permit loads, and in the case of bridges and tunnels on the interstate, all federal legal loads.

Safety related features

If the design exception request involves any features that are safety related, then sufficient crash data and history is attached to the request to support the reasons for justification. A summary report of the crash information is acceptable if the volume of the data is excessive. Examples of safety related features include, but not limited to, the following: design speed, stopping sight distance, passing sight distance, lane width, shoulder width, shoulder type, rumble strips, turn lanes, bridge width, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance, guardrail, etc. Any other items that may be perceived as a safety concern will also follow these requirements.

In addition, if the design exception request involves safety related features that are adequately addressed in the AASHTO Highway Safety Manual, then documentation of the exception should include a safety analysis as described in the manual. Typically, this process will involve two primary determinations:

  • Calculate the expected change in crashes from existing conditions to standard design conditions
  • Calculate the expected change in crashes from existing conditions to the proposed design.

The proposed design should take into account any design exceptions as well as any additional safety features above and beyond the standard design.

By making these two determinations, a quantitative safety comparison can be made between existing conditions, the standard design, and the proposed design. This information, along with other project considerations, can be used to help determine the best design alternative. A list of features currently addressed by the manual include: lane width, shoulder width, shoulder type, center line rumble strips, horizontal alignment (length, radius), grade, roadside hazard rating, fixed objects, driveway density, median width, sideslope, lighting, intersection skew angle and turn lanes. Not all features in the manual are addressed for each facility type.

131.1.6 Revising an Approved Design Exception

Changes in project scope or design criteria can result in changes to design exceptions that have previously been considered. In these cases, a revised design exception must be completed and approved (as described above). The original design exception should accompany the revised information in order to illustrate the changes. The transmittal letter should address the changes and an explanation of the circumstances leading to the revision.

131.1.7 Deficient Vertical Clearances on Interstates

Maintaining the integrity of interstates for national defense purposes has long been recognized. Interstates are intended to be constructed and maintained to meet AASHTO Policy as stated in A Policy on Design Standards - Interstate System, which is incorporated by reference in 23 CFR 625. Maintaining standard vertical clearances to the extent possible for defense mobilization is considered particularly important and is a focus at the national level. As a result, the FHWA has agreed that all exceptions to a 16 ft. vertical clearance standard for the rural interstate and certain single routings on the urban interstates be coordinated with the Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA) of the Department of Defense. This coordination applies whether it is a new construction project, a project that does not provide for the correction of an existing substandard condition, or a project that creates a substandard condition at an existing structure. The steps involved are:

1. For a vertical clearance over any interstate highway that will be less than 16 ft. meeting the above criteria, the district submits to the Design Division a completed SDDCTEA Interstate Vertical Clearance Coordination Form along with a Design Exception for vertical clearance.
2 The Design Liaison Engineer emails the Bridge Inventory Analysts and requests the Structure NBI number for box 2 on the Vertical Clearance Design Exception Coordination with SDDCTEA Form.
3. Concurrent with the submission or routing of the Design Exception, the Design Liaison Engineer submits the form to the SDDCTEA and copies FHWA. This may be done electronically using the contact information on the Vertical Clearance Design Exception Coordination with SDDCTEA.
4. A response from SDDCTEA should occur within 10 working days following receipt of the coordination request. Receipt of the request can be verified with SDDCTEA via telephone or fax. If there is no response after 10 working days following receipt, it can be determined that SDDCTEA does not have any concerns about the proposed exception.
5. The Design Liaison Engineer informs FHWA as to the final outcome of the SDDCTEA request.