Who is responsible for designing traffic lights?

The Traffic Engineering department of the state, county, city or local agency is responsible for traffic light design, as noted by the Federal Highways Administration. The most commonly referenced materials for traffic agencies are the Highway Capacity Manual and Manual on Uniform Traffic Control Devices.

Maine’s Traffic Engineering Design Section is responsible for all aspects of traffic light design including the timing, lane assignments and phasing of existing and new traffic signals, according to Maine.gov.

In Minnesota, the Office of Traffic, Safety and Technology determines uniform guidelines for traffic engineering in the state. The office oversees eight different district traffic engineers, some of whom sit on the state signal committee, notes the office's website.