A critical component of any traffic signal management program is maintenance. Preventive maintenance ensures that components of a traffic signal system that have a limited service life are regularly cleaned, replaced, re-calibrated or tuned to prevent equipment failures, ensure optimal operations and extend the life of the infrastructure. Reactive maintenance involves providing emergency response when equipment fails to restore the signal to normal operation.

When managing infrastructure assets, preventive maintenance must be balanced with reactive (corrective) maintenance to ensure optimal performance and reliability. This concept is often used in pavement, facilities and fleet management, but is equally applicable to traffic signals.

Too little preventive maintenance leads to failures and the need for emergency repairs. Emergency repairs can be costly when equipment, replacement components and compensation for overtime are considered. Lack of preventive maintenance may also affect the performance of a signal – for example, when a loop detector fails or a pedestrian push button sticks.

On the other hand, excessive corrective maintenance beyond that which is required can raise overall maintenance costs. According to the International Municipal Signal Association (IMSA), 80 percent of an agency’s technician time should be spent on preventive maintenance while 20 percent should be spent responding to failures or emergencies.

Inadequate preventive maintenance of traffic signals can also have the serious consequence of a failure contributing to a motor vehicle collision. While municipalities have sovereign immunity in some situations, it does not apply when a suit is brought against a municipality for death or injury caused by improperly maintained roads. Section 13a-149 of the Connecticut General Statute states that “Any person injured in person or property by means of a defective road or bridge may recover damages from the party bound to keep it in repair…” A malfunctioning traffic light is considered to create a defective roadway under the statute.

Municipalities may limit their exposure to liability by ensuring personnel are properly trained, performing and documenting regular preventative maintenance activities, and using appropriate traffic control plans while performing maintenance.

The T2 Center will soon issue a tech brief on preventive maintenance with a sample PM checklist to assist municipalities in planning preventive maintenance activities by in-house staff or including them in vendor contracts.

*The information in this article is for informational purposes only. Please seek the advice of your agency’s corporation counsel regarding municipal tort liability as it relates to traffic control signals.*

Additional traffic signal resources can be found on the T2 Center website at: https://www.t2center.uconn.edu/signalcircuitriderNEW.php