7.9.1 Signals

A comprehensive investigation of traffic conditions and characteristics of potential signal locations is necessary to determine the need for signal installations and to collect data for the design and operation of signals.
Traffic control signals must not be installed unless the investigation reveals that at least one of the warrants contained in the TMUTCD is met. Meeting an hourly volume warrant is only the first step to justifying a traffic signal. The TMUTCD states that warrants are a threshold condition and not a substitute for engineering judgment. All traffic factors must be considered when determining if a signal(s) must be installed.
Signal operation types include full-actuated, semi-actuated, pre-timed or combinations thereof. They can also be operated at isolated intersections, in coordination with nearby signals or as mid-block operations.
If the department is not responsible for the traffic control signal system operation and maintenance (e.g., appurtenances, software, hardware and timing), then an agreement must be established with the controlling agency before the signal is installed and activated.
Considerations in the design of traffic signals include:
  • Coordinate signal design and details with LG if signals will be operated and maintained by a LG. Obtain concurrence from the LG for locating signals within their jurisdiction and ensure that required agreements are executed as described in TxDOT’s
    Negotiated Contracts Procedures Manual
    ;
  • Coordinate signal plans with roadway, drainage and utility plans;
  • Coordinate to have geotechnical foundation design performed for traffic signal foundations with District bridge and laboratory staff;
  • Coordinate intersection geometry, turn lane lengths, median types, and access control at signalized intersections with roadway and traffic engineers. In urban areas having remote signal timing control and coordinated signals, signal control design must be discussed with the local entity. If the project is located along a designated bike route, bicycle signals may be appropriate, and should be linked and timed with the vehicular traffic signals. Any through bicycle movements will require prohibiting permissive movements for vehicles (e.g., not right on red), see the TMUTCD for further guidance.
  • Signals and supports must be located to maximize safety and meet PROWAG and TAS accessibility requirements. All pedestrian features and pedestrian signal poles must be accessible to persons with disabilities;
  • Detail intersection pavement markings, ramps, and walkways before preparing pedestrian signal layouts to ensure proper location of pedestrian poles and signal heads;
  • Account for mid-block pedestrian signals as necessary; and
  • Pedestrian crossing times must be sufficient for the expected user population to cross the street safely and meet or exceed the requirements contained in the TMUTCD.