902.22 Maintenance Guidelines

902.22.1 Controllers and Equipment

902.22.1.1 Controller and Cabinet Replacement Program

Guidance. Routine replacement of control equipment assists in maintaining and operating a reliable system. Signal controllers should be replaced at 10 years of age or older and cabinets should be replaced at 25 years of age or older.

Option. Cabinets and controllers may be replaced sooner than the recommended age. Controllers or cabinets experiencing higher than normal maintenance should be considered for replacement regardless of age.

Support. Controllers replaced under this replacement program do not automatically generate a need to modify ADA-related pedestrian accommodations. However, some controller replacements will lead to a need for such changes. For more information on this subject, see EPG 642.4 Impact of the Project Category on ADA.

902.22.1.2 Approved Product List and Equipment Evaluations

Support. MoDOT has developed an Approved Products List (APL) containing many items used in signals and lighting. The APL is based on equipment that meets department specifications and has been tested for a specified test period with satisfactory performance. This list helps MoDOT purchase reliable products for traffic signals and highway lighting. This list is included in the bid requests for applicable equipment purchases and is also included in construction contracts that include signals or lighting.

MoDOT frequently tests new products and equipment for signals. These new products can be installed on a construction project, purchased on parts orders or with controller orders. Only a limited number of units will be accepted for test statewide until an item is added to the approved products list.

Standard. All equipment evaluations are coordinated through Traffic and are reviewed by the Traffic Signal Quality Circle. The vendor supplying the equipment must fill out the New Product Evaluation Form and provide equipment specifications and a certification that the equipment meets MoDOT specifications before the test is performed. The equipment is tested for the period specified on the approved products list.

Option. Products that are not performing satisfactorily may be replaced at any time if the vendor cannot provide timely correction of the problem or if unsatisfactory operation of the intersection results.

Standard. Upon completion of the test, the district shall complete the Product Evaluation Form - Signal and Lighting Equipment and submit it to Traffic. The evaluation is reviewed by the Traffic Signal Quality Circle for addition to the APL or for rejection.

If a vendor is proposing a product that does not meet department specifications, the vendor shall provide a written explanation to Traffic of why the product does not meet the current specifications and why the product should be evaluated. If approved for evaluation, the product is tested for the specified period as described above. After evaluation and if the product is satisfactory, Traffic will consider making a recommendation to revise the applicable specifications. If specifications are not revised, then the products that does not meet specifications will not be added to the approved products list.

902.22.1.3 Experimental Equipment

Guidance. MoDOT often evaluates experimental equipment for traffic signals. Experimental equipment can be new products or products that vary considerably from our current standards or practices. The evaluation of experimental products can be initiated by district or Central Office staff, as part of a research project, as an implementation of an employee idea, etc.

The evaluation of experimental equipment for traffic signals is coordinated through Traffic and may involve other functional units such as Research. If the evaluation is part of a research project, then the project will provide guidelines for testing. Products can be evaluated in a similar manner to that described in EPG 902.22.1.2 Some items to consider before evaluating experimental equipment are as follows:

• What improvement will the equipment provide?
• Does the equipment conform to National and State standards?
• Is the equipment cost effective?
• Are funds available?
• What are the advantages and disadvantages of the equipment?
• How will the effectiveness of the equipment be tracked?
• What criteria will be used to determine if the equipment is satisfactory?

The Product Evaluation Form – Signal and Lighting Equipment can be used for evaluation of experimental equipment.

902.22.2 Annual Orders and District Signal and Lighting Equipment Purchases

Guidance. Highway Safety and Traffic Division will coordinate annual orders for signal and lighting equipment purchases. The intent of annual orders is to combine orders from all districts to develop larger quantities and to save duplication of work.

Standard. Annual orders are limited to items that will be purchased in larger quantities and can be bid competitively. For signal and lighting annual orders, it is important that only these types of items be included in the requests. Proprietary items, model specific replacement parts, and small quantity items are to be purchased at the district level.

Option. There are many common "off-the-shelf" items that can be purchased at local suppliers, saving time, and in many cases money. Traffic staff may ask the districts to order some items from annual orders on their own if it does not appear they will benefit from the annual order process.

Standard. District purchases are to follow General Services’ guidelines for purchasing.

Support. Some information that General Services might need to include in equipment bids are:

• Reference to the Standard Specifications (if applicable). Indicate the exact section that applies.

• Reference to the approved products list (if applicable). Include a copy of the current list.

• Supplemental specifications (if applicable). Include a copy of the specifications. An example is signal controller purchases. Traffic maintains supplemental purchase specifications for controllers and other items.

902.22.3 Signal Maintenance

Support. Traffic signal maintenance activities can be divided into three major areas: preventive maintenance, emergency repairs, and follow-up work. Signal maintenance personnel are responsible for these tasks.

See EPG 902.1.10 for MUTCD content regarding traffic signal maintenance.

Guidance. If a traffic signal is dark for signal maintenance, consideration should be given to notifying the police agency whose jurisdiction the signal is located in. If the signal can be flashed instead of dark, a request for police assistance might not be necessary unless the time of day, traffic volumes and congestion dictate a need.

If it is necessary to turn the signal off or a malfunction occurs and traffic cannot be handled by a flashing operation or stop signs cannot be installed immediately, the police should be notified that their assistance is requested until the signal can be repaired or stop signs can be installed.

902.22.3.1 Preventive Maintenance

Support. Preventive maintenance (PM) for traffic signals, includes the systematic inspection, cleaning, testing, adjustment and completion of non-emergency repairs needed to ensure it will function as efficiently and reliably as intended throughout its expected life cycle.

A warranted and well-maintained signalized intersection is one of the best services that can be offered to the public by the department. When efficiently operated it represents a direct savings through reductions in delay, fuel consumption, and greenhouse gas emissions while providing safe intersection traffic control. In the long run, a well-executed preventive maintenance program will reduce the number of emergency maintenance calls and will help ensure reliable and efficient traffic control.

Standard. A schedule of inspections shall be prepared for the purpose of preventive maintenance in accordance with the recommended guidelines set forth herein and administrative supervision shall be maintained to see that maintenance is performed as scheduled. MoDOT’s standard for performing these inspections is to evaluate each traffic signal within a two-year time span.

Guidance. Several factors should be considered when preparing the preventive maintenance schedule to ensure the effort is focused in the most useful locations. Each traffic signal will differ as to the maintenance attention required at different times in its expected life cycle. Preventive maintenance efforts in addition to that described in the Department’s standard should be focused on traffic signals identified through review and consideration of the following.

• Review of the frequency of call reports

A statistical report should be prepared at least once each year from the MoDOT Customer Service Center call report database. Those signals producing the highest 20% of call reports should be reviewed to determine if extra maintenance efforts could improve reliability. Call reports that proved to be signal timing related rather than maintenance related should be removed from this analysis and forwarded to engineering staff for review.

• Review of recent modifications, additions, or contract work

Signals that have received recent modifications and newly constructed signals can certainly benefit from a thorough, post-project inspection. Inspection by trained signal maintenance personnel can help ensure that any potential maintenance issues are discovered early and resolved before problems develop. Any traffic signal that has undergone modifications or construction since the last inspection cycle should be considered for an additional preventive maintenance review.

• Review of previous inspection reports

Traffic signals that might have structures or features nearing the end of their life cycle might need more frequent inspections to help determine and prioritize replacement needs. The type of signal structure, vulnerability to accident damage and exposure to extreme weather might also be cause for more frequent inspections. Signals needing this additional focus can be identified through review of any concerns noted on previous preventive maintenance inspection reports and should be considered for inclusion in the preventive maintenance inspection schedule.

Reports in checklist format are available to aid the preventive maintenance process for cabinet and control equipment and for signal supports, signal heads and pull boxes. More detailed preventive maintenance guidance can often be found in the manufacturer’s equipment manuals for the many varied components of signal structures and control.

A preventive maintenance program should include the following:

LED Signal Indications

Scheduled replacement of LED indications should be accomplished every 10 years. Inspection of the indications between changes should include visual verification that each indication is operating and is oriented properly within the signal head.

Signal Heads

All signal heads should be plumb and in proper alignment to be visible from the appropriate lane. Signal heads capable of programmable viewing angles should be checked for visibility and non-visibility from the appropriate lanes. The points of signal head attachment, especially on span-wire installations and post top mounting should be checked to see that all components are sound and secure. If top mounted signal heads are loose and cannot be tightened, consideration should be given to installing a longer pedestal post and side mounting the head. Check that all setscrews are in place and tight.

Overhead signals and associated hardware should be checked for proper clearance over the roadway. Signal section doors should be observed to see that they are tightly secured to the signal section housing. The condition of the signal heads should be evaluated to determine if replacement might be necessary. Backplates and signal visors should be checked for proper attachment and condition and replaced if necessary.

Signal Supports

Signal support posts should be plumb or raked as planned. Steel posts and mast arms should be inspected at seams and joints for signs of stress or fatigue. Particular attention should be directed to the base plate and mast arm plate joints and associated welds. Any indication of stress or cracking should be marked and called to attention for further evaluation. Bolts and nuts should be checked for tightness and rust. Where possible anchor bolts should be visually examined for signs of rust or deterioration. Steps should be taken to replace any missing handhole or post top covers. Wooden support poles should be checked for bending and general condition.

Concrete signal post bases should be checked for settling or shifting, cracking, severe spalling or similar weather-related deterioration. The gap between the post foundation and the post base plate should be filled with galvanized wire screen. On older installations, grout might have been used to fill this gap. If this is the case, consider removing the grout and installing wire mesh if the grout is broken or appears to be retaining moisture.

Guy cables, support cables, tether cables and anchors should be checked for tautness and for signs of strain. The cable's physical condition should be checked to see that there are no broken strands. Cable attachment clamps should be checked for tightness. Anchors should be checked for movement and general condition. Anchors and guy cables can loosen up over time as they are subjected to wind loads, changing soil conditions and even vehicle accidents. This loosening can affect clearance of the signal over the roadway. Clearance between the roadway and the bottom of signal heads is to be maintained between 16 and 19 feet.

To minimize signal head movement, cable spans should not have excessive sag. Tether cables should be maintained in a straight line across the bottom of the signal heads. If excessive sag is found, the cable should be tightened. Minimizing movement does not only enhance signal head visibility but also reduces stress on the signal heads, cables and associated hardware.

Vehicle and Pedestrian Detection

Each detector should be observed to see if it is operating properly. Equipment is available for troubleshooting detectors. It is highly desirable to make and record the impedance and resistance of each loop when installed. Such information can be invaluable in trouble shooting induction loop detection systems. Each push button should be pressed to confirm that it actuates the pedestrian phase. Check pedestrian signs for condition and proper alignment.

Pull Boxes

All pull boxes should be checked for cracking of the concrete apron, and condition of the lid. Signs of settling could indicate sidewall failure. Consideration should be given to adding a drain if the pull box is holding water. Detector loop splices and the grounding system should also be checked for tightness and condition.

Cabinets

The outside surface of the cabinet should be inspected for overall physical condition. Brush and vegetation should be under control in the area around the cabinet. Doors should fit tightly when closed and the gasket should seal properly. Locks and hinges should move freely and be lubricated if necessary. The inside of the cabinet should be clean, and all assemblies should be free of dust, pests or signs of moisture intrusion. Filters should be in good condition and replaced or cleaned to ensure proper ventilation. Ventilation fans should be checked for operation and the appropriate thermostat setting should be verified. Anchor bolts on the cabinet should be checked for tightness to the base. The conditions of the duct seal and cabinet seal as well as the ground rod clamp and wire should also be evaluated. Cabinet documentation including wiring diagrams, timing sheets, work records and intersection layout or plan sheets should be present. Police door lock, flash switch and manual control should be checked for proper operation.

All terminals should be checked for tightness. Relays, plug-in modules, and connectors should also be checked for proper fit and operation. A voltage measurement should be made and recorded at the main voltage input terminal block. This voltage measurement should agree with the voltage measurement at the service disconnect and should be within the tolerances of the signal control equipment. Voltages at the field terminals should also be checked. Lightning protection devices should be examined to see that they are in condition to activate if a surge should occur. If no lightning protection is present at the service line input, it should be added.

Flashers should be checked to ensure they operate with a flash rate of 50 to 60 times per minute.

Controllers

Verify that the cabinet timing sheet matches the programming currently in the controller. Check for the proper operation of programmed functions.

Preemption Equipment

Preemption equipment should be regularly checked for proper operation. Preemption equipment is typically installed at critical intersections (near railroad tracks or emergency vehicle routes) so malfunctioning preemption equipment should be repaired or replaced as quickly as possible.

MoDOT’s preventive maintenance measures should extend only to the equipment owned and maintained by MoDOT. When preemption equipment is not owned, operated, and maintained by MoDOT, testing of preemption system operation should be coordinated with the other involved agency and can be scheduled separately from the preventive maintenance inspection.

Utility Service

The utility service should be examined to ensure that the electric meter enclosure, conduit and boxes are in sound condition and securely mounted. Surge protection should be present at the service. Circuit breakers should be sized appropriately and labeled as to their function. All electrical connections must be tight and the service should be properly grounded. Supply voltage should be measured at the service disconnect or main breaker and low or high supply voltages should be reported to the utility company for correction if tolerances are exceeded with which the signal control equipment is designed to work. If the service is an overhead drop, ensure that the drop and connection point is clear of tree limbs.

Battery Backup Power Supplies

Enclosures or cabinets for battery backup systems should be inspected using many of the same inspection points considered for traffic signal control cabinets. Inspect the cabinet for physical damage. Locks, hinges, doors, ventilation, and moisture seal should all be evaluated. Battery condition and age should be considered and noted on the inspection form. Connection points should be examined to ensure they are securely fastened and free of corrosion. Control unit self-tests and power transfer tests can be very useful in validating the system. Careful consideration of the potential effect on signal operation is essential before scheduling and performing such testing.

902.22.3.2 Conflict Monitor and Malfunction Monitor Testing

Guidance. It is important to test monitors periodically to ensure their reliability. Monitors should be tested according to the following guidelines: Annual tests should be conducted and recorded as part of the annual preventive maintenance procedure. The documentation of these procedures should be stored with other permanent records. It is recommended that field tests be performed during low traffic volume periods in order to minimize disruption to traffic.

902.22.3.2.1 Conflict Monitor Unit Test Procedure

Guidance. The conflict monitor should be tested annually with a computerized conflict monitor tester. This is done by removing the intersection's monitor and running a complete test with the conflict monitor tester unit. If the test is to be completed in the field, a spare monitor should be installed temporarily while the test is being performed. Monitors can also be shop-tested by rotating pre-tested monitors to the field. Documentation of the tested monitor should include the following:

1. Date
2. Name of Technician
3. Location – includes intersection name, city and/or county
4. Serial number of conflict monitor
5. Comments regarding fail or pass conditions

The monitoring unit’s permissive programming card should be inspected for physical condition. The jumpers or diodes that establish monitor channel concurrency should also be evaluated and verified as correct for the intersection in question.

Failed monitors should either be repaired so that they pass the monitor test or replaced with a monitor that passes the test.

To ensure the reliability of the computerized monitor tester, a calibration of the unit should be done annually. The units need to be returned to the manufacturer in order for this calibration to be done properly. The districts should establish a yearly program of having their conflict monitor testers returned to the manufacturer and the recalibration performed.

902.22.3.2.2 Cabinet Test Procedures

Guidance. Two tests should be performed to check the cabinet wiring and operation as related to conflict monitoring functions. These tests should be performed as part of initial cabinet setup and should be repeated at the time of any cabinet wiring modifications or additions. These tests are not required during annual preventive maintenance monitor unit testing.

(A) Conflict Test An actual conflict condition is induced by means of a jumper wire. This is most commonly done by placing one end of the jumper wire on a green terminal output and the other end on a conflicting green terminal output. Once power is applied to either green terminal, the conflict monitor should trip causing signal control to be transferred to flashing operation. A push button with leads and alligator clips can be helpful for performing this test. (B) Harness Test

For solid-state pre-timed, NEMA TS1 and Type 170/2070 controllers, the monitor harness or harnesses should be tested for continuity and to ensure that all wiring to the monitor is intact and that the correct load switch circuit goes to the correct channel in the conflict monitor. The results of the test are recorded on the Conflict Monitor Continuity Checklist.

Conflict Monitor Continuity Checklist

Conflict Monitor Continuity Checklist

This test should be performed during initial cabinet set-up and any time changes are made that affect the monitor wiring or operation (i.e. phasing changes). This test can also be performed at other times as needed. The harness test is not required for NEMA TS2 controllers since the cabinet diagnostics continuously check cabinet conditions.

Conflict Monitor Harness Tester presents the procedure for using a harness tester. The harness tester also shows connector terminations for 6 and 12-channel conflict monitors. More detailed information on conflict monitors is found in the NEMA Standards Publication No. TS-1, Traffic Control Systems. A similar device can also be developed for Type 170/2070 controllers. This tester can be helpful as a troubleshooting tool as it can be used to isolate some cabinet wiring problems.

902.22.3.3 Emergency Maintenance

Guidance. Occasionally traffic signals, flashers and lights malfunction or are damaged from vehicle crashes, acts of nature and/or other unexplained phenomena. Some of these occurrences will constitute an emergency requiring an immediate response, while others might indicate a lower priority response. Sound judgment should be used when evaluating the priority of signal malfunctions or damage.

Generally, flashers have lower priority than traffic signals. Refer to the Incident Response Plan and Incident Response Priorities for detailed information regarding emergency response for traffic signals, flashers and lights.

During after-hours, the electrician might have to contact the highway patrol or local police and the power company.

902.22.3.4 Maintenance Limits

Guidance. No major repair should be attempted while the controller is in service. Where possible, the availability of a spare unit for each type of assembly minimizes interruption of signal operation when that unit must be removed for servicing or repair.

Field servicing of solid-state equipment should be limited to the exchange of modules and assemblies known to be good for those thought to be defective. Due to the sensitivity of some parts, it is important that they be stored in the shipping containers until used and then handled with minimum hand contact.

902.22.3.5 Equipment Replacement and Repair

Guidance. Sound judgment should be used when making decisions about replacing or repairing malfunctioning signal equipment. When possible, field repairs should be limited to operations that result in minimal down time to signal operation. Shop repairs are preferable where spare equipment can be installed to maintain signal operation.

When deciding to repair or replace a piece of equipment, consider these factors:

- Relative condition of the piece of equipment.

- Remaining usable life of the piece of equipment.

- Cost of repairs in personnel time or repair shop costs vs. cost of new equipment.

- Availability of replacement parts.

- Is the piece of equipment functionally obsolete?

The evaluation of these factors might determine that it is more cost effective to replace a piece of equipment than to repair it.

Option. Repair work may be performed by district personnel or may be sent to a repair shop. This decision is based on the available expertise of personnel, time demands on the shop and the nature of the malfunction.

902.22.3.5.1 Crash Damage to Controllers

Standard. Occasionally a crash will result in the destruction of a signal controller. Whenever this occurs, MoDOT tries to collect for the damages incurred. The following depreciation schedule shall be applied when determining the present worth of an existing controller that has been damaged.

Age, In Years	Worth, % of Original Value
0-1	100
1-2	99
2-3	98
3-4	96
4-5	93
5-6	89
6-7	85
7-8	80
8-9	74
9-10	67
10-11	60
11-12	52
12-13	43
13-14	33
14-15	23
15-16	12
16 or More	2

902.22.3.5.2 Crash Damage to Signal Heads and Supports

Standard. Whenever damages occur to signal heads and their supports as the result of a crash, collection for damages shall also be attempted. Straight line depreciation shall be used with a 15-year life used for all signal heads and all temporary span wire supports. A 25-year life shall be used for all permanent supports.

902.22.4 Record Keeping

Standard. Each district shall keep and maintain documentation on each signalized intersection. Each district will be required to maintain (1) Signal Maintenance Files and (2) a Module and Assembly Repair File. The Signal Maintenance File shall be kept on a per intersection basis, whereas the Module and Assembly Repair File shall be kept on a module and assembly type basis. Refer to Figure 902.22.4.1 for guidelines regarding record keeping for signal-related information.

Standard. The information being recorded shall be accurate and legible. Completing documentation for each signalized intersection requires more time of those involved in signal operation and maintenance, but the time required to do so is considered minimal and over a period of time will more than justify the time spent.

It is important to retain records for the appropriate amount of time before information is discarded. For more specific details on document retention, review MoDOT’s Retention Schedule.

In general, design and construction-related information such as design plans and contracts are retained permanently. For signals constructed on contracts administered by Construction, Construction typically retains contract records. Design typically retains plans for projects that are let under the right of way and construction program. For signals constructed by permit, department forces, or a combination of department forces and contract work, district traffic is responsible for retaining design and construction documentation.

All other records pertaining to operation and maintenance of traffic signals shall be retained a minimum of seven years. Each district is responsible for retaining these records. The following reports and records should be maintained. Some example forms for various records are included, but districts can choose to modify them as needed in order to meet their specific needs.

1. Signal, Flasher, and Lighting Inventories

Traffic Signal, Flasher, and Lighting Inventories

These inventories contain each signalized intersection, flasher installation, and lighting installation on MoDOT right of way. The inventories are part of the Transportation Management System (TMS). District personnel shall maintain the TMS signal, flasher, and lighting inventories on an ongoing basis. Guidance is available in the Traffic Signal, Flasher, and Lighting Training Manual.

2. Intersection Plans

Intersection plans are provided for each signalized intersection, although plans for older installations can be difficult to find. At a minimum, the documentation shall be in the form of signal plan sheets from the final plans of the project or drawings. The plans shall show the lane widths, all signal indications and their location, detector placement, and approximate geometrics with regard to skew. Intersection plans shall be available in the district office, in the signal shop’s signal maintenance file, and can be scanned and stored in the signal inventory in TMS.

3. Signal Phasing and Timing Record

Signal phasing and timing is determined, computed, and stored by district office personnel. Old signal phasing and timing shall be archived. This documentation shall be accessible electronically or at the controller cabinet, at the signal shop, and at the district office or TMC. It can also be stored within the signal inventory in TMS.

4. Traffic Signal Service History

A historical record of the service history shall be kept in the controller cabinet. Entries shall be completed by anyone observing the operation of the equipment or performing maintenance. The date of the observation or call to the controller shall be indicated with a very brief note of explanation and initialed by the person entering the information. This form shall be filed in the signal shop whenever the sheet becomes full. See Figure 902.22.4.2 for an example form.

5. Preventive Maintenance (PM) Checklists

Checklist

Statewide Signal/Lighting/Flasher Preventive Maintenance Checklist

There is a checklist available for preventive maintenance: PM Checklist for Signal Supports, Heads, Pull Boxes, and Cabinet and Control Equipment. The list contains a number of items relating to the intersection operation that shall be examined on a periodic basis in accordance with the recommended guidelines set forth herein. Each item on the list shall be examined during the PM check. A check opposite of each individual item indicates that item has been examined and found in proper operating and physical condition. On completion, the PM checklist shall be returned to the signal shop for review and subsequently placed in the signal maintenance file for that particular intersection.

6. Emergency Signal Maintenance Work Records

This record is essentially an emergency work record that can be used to record any maintenance activity performed at an intersection that is not considered preventive maintenance. The record shall be maintained as either a paper copy or a computer database.

(Figure 902.22.4.3 and Figure 902.22.4.4).

7. Bench Repair Label

The bench repair sticker shall be attached to any component, module, or assembly when it is removed from an intersection and taken to the signal shop for repair. When the unit is repaired, the label is completed, indicating what was done or replaced during the repair. When the unit is ready to be returned to service, the label is then placed in the module and assembly repair file for that particular unit.

8. Conflict Monitor Information

Conflict monitor test results, cabinet test results, conflict monitor card programming and any other important information shall be kept in the signal shop. Forms for documenting conflict monitor programming include:

- Figure 902.22.4.5 (Conflict Monitor Program Card)

- Figure 902.22.4.6 (NEMA TS2 Conflict Monitor Program Card) and

- Conflict Monitor Program.

9. Cabinet Drawings

Cabinet drawings and other critical paperwork shall be kept in the controller cabinet, in the signal shop, and can also be stored in the signal inventory in TMS.

Guidance. District personnel should store all intersection photographs within the TMS signal inventory in TMS. Photographs should be updated as needed, but the older photos should always be retained. Intersection photographs that can be beneficial include, but are not limited to, photographs of the signal cabinets, components within the signal cabinet, and the power supply.