> Chicago has about 2900 traffic signals throughout the city. About 470 of these signals are interconnected through a fiber-network that facilitates the centralized monitoring and control of signal operations. Whether interconnected or not-interconnected, the signals are programmed to synchronize with signals immediately around it so that vehicles will pass through the intersections most efficiently. New signals are added and old signals are modernized every year depending on the need and availability of funds. While OEMC/Traffic Management Authority is responsible for maintaining the signal coordination and timing, Division of Electricity at CDOT is responsible for the maintenance of the signals and CDOT is responsible for the physical design, construction, and timing of signals.
It appears that the City of Chicago maintains their own. As noted there, that is maintained by the division of electricity ( https://www.cityofchicago.org/city/en/depts/cdot/provdrs/tra... ), which also maintains all street lights and signs. When one gets to a point where the municipality knows that there will always be work for some number of people - its cheaper to hire those people permanently than contract it out. This also provides a better SLA for the city (tax payers get rather annoyed if the street light is out and the response from City Hall is "we told the contractor about it, but they haven't responded yet - its the holidays.")
But cities of a sufficient size (pulling up Chicago because its probably larger than the sufficient size), you find https://webapps1.cityofchicago.org/traffic/about.jsp
> Chicago has about 2900 traffic signals throughout the city. About 470 of these signals are interconnected through a fiber-network that facilitates the centralized monitoring and control of signal operations. Whether interconnected or not-interconnected, the signals are programmed to synchronize with signals immediately around it so that vehicles will pass through the intersections most efficiently. New signals are added and old signals are modernized every year depending on the need and availability of funds. While OEMC/Traffic Management Authority is responsible for maintaining the signal coordination and timing, Division of Electricity at CDOT is responsible for the maintenance of the signals and CDOT is responsible for the physical design, construction, and timing of signals.
It appears that the City of Chicago maintains their own. As noted there, that is maintained by the division of electricity ( https://www.cityofchicago.org/city/en/depts/cdot/provdrs/tra... ), which also maintains all street lights and signs. When one gets to a point where the municipality knows that there will always be work for some number of people - its cheaper to hire those people permanently than contract it out. This also provides a better SLA for the city (tax payers get rather annoyed if the street light is out and the response from City Hall is "we told the contractor about it, but they haven't responded yet - its the holidays.")