COVID-19: Transportation Response Center
The operation of a traffic control system should closely mirror a city’s policy goals and objectives. Managing traffic signals is important because signals directly impact the quality of the transportation system. While geometric enhancements to a corridor may demarcate space for bikes and buses and create a more multi-modal cross-section, signal timing influences delay, compliance, safety, and mode choice.
Traffic signal timing that provides insufficient time for someone to cross the street, for instance, is likely to create an unpleasant experience and may discourage walking entirely. Likewise, significant delays may cause street users to violate the traffic signal or take unsafe risks entering intersections.
Shorten Signal Cycles to Increase Turnover
Short signal cycle lengths minimize delay in a complex network environment, reducing wait times in all directions and creating crossing opportunities at closer intervals. Avoid simultaneously adding multiple turn lanes and increasing turn phase intervals. Do one or the other, but not both.
Prioritize Walking, Bicycling, and Transit
Use signal priority tools, such as leading pedestrian intervals, synchronized signals for bicycles, or transit signal priority along corridors with established or desired modal priority.
See Coordinated Signal Timing
Keep the Number of Signal Phases to a Minimum
While separating traffic through signal phasing may have safety benefits, additional phases increase wait times for everyone by increasing the overall length of the signal cycle. Consider turn restrictions at dangerous intersections or, where turn volumes necessitate a dedicated turn phase, introduce a protected left-turn phase.
See Split Phasing
Time Signals to the Speed you Intend Traffic to Go
Synchronize signals at or below the target speed to maintain safe vehicular travel speeds and discourage speeding, especially on 1-way streets.
Adjust Timing for Peak and Off-Peak Volumes
Signal timing should be managed for both peak and off-peak volumes. Timing may be adjusted to meet different levels of activity throughout the day.
Use FixedTime Signals as Opposed to Actuated Signals
Fixed, rather than actuated, signals are preferable in urban areas to increase the predictability of the urban environment and ensure consistent opportunities for pedestrian crossings and cross traffic.
See Fixed-time vs. Actuated Signals
Adapted from the Urban Street Design Guide, published by Island Press.