Traffic Signal Preventive Maintenance

Edited by Airton G. Kohls (Source: Institute of Transportation Engineers

Traffic signal maintenance encompasses Preventive Maintenance and Response Maintenance. The objective of Preventive Maintenance is to prevent the failure of traffic signal equipment before it actually occurs and to preserve and enhance equipment reliability by replacing worn components before they actually fail. Preventive maintenance also helps reduce the agency’s exposure to liability and extend the life of the installation. With periodic visits to the intersection, agencies can identify potential problems that can be addressed before the signal fails or malfunctions. It ultimately optimizes the use of manpower and resources.

To help reduce an agency’s liability proper documentation is imperative. It is good practice for a maintaining agency to readily have record drawings that include: modifications to the original design, approved timing directives. Also a logbook recording: date and time, name of technician servicing the equipment, reason for visit, work performed, parts replaced, conditions on arrival and conditions when leaving the intersection.

Extending the Life of the Installation

Some small preventive tasks may help keep the intersection operating properly and may extend the life of some components, especially electronic components:

• Change the air filter;
• Adjust the cabinet thermostat;
• Make sure the cabinet fan is working properly;
• Check if cabinet door gasket is cracked or missing to avoid potential rain and moisture damage to components;
• Make sure all signal hardware is tight and properly installed;
• Check if loop detectors are sealed.

Frequency

Preventive maintenance should be performed at regularly scheduled intervals, typically every six months and a minimum of once a year. Review maintenance records or service calls to determine trends and design an appropriate schedule. It is also good practice to inspect traffic signals after severe weather.

Baseline Assessment

Performing a baseline assessment is a valuable tool that provides an agency with information on the condition of the traffic signal equipment and the performance of the intersection, helping to plan for future actions. The end result includes actions that you must do, should do and can do. It includes:

• A physical inventory of the equipment and hardware in each intersection ;
• A physical layout of the equipment at the intersection;
• The number of lanes per approach, along with striping and pavement markings;
• Identification of operational deficiencies through visual observation supplemented with photo documentation;
• Identification of design deficiencies;
• Identification of missing, worn, or damaged equipment;
• Review of past maintenance practices.

Minimum Requirements Checklist

At a minimum, preventive maintenance should include:

• Check vehicular signal heads;
• Check pedestrian signal heads and detection;
• Check all signal poles, mast arms and mounting hardware;
• Check span wire signal installations, including mounting hardware;
• Check the conduit system and junction boxes, including grounding and bonding;
• Check the condition of the traffic signal cable, including splices;
• Check vehicle detection;
• Clean and check the condition of overhead signs;
• Check the operation of the uninterruptible power source (battery backup);
• Check controller and meter cabinets;
• Check controller assembly;
• Check pre-emption operation.

For additional information consider attending our Traffic Signal Academy workshop: Traffic Signal Installation and Maintenance. Check our current calendar at: http://trafficsignalacademy.utk.edu/dates-locations.php

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