Traffic Signal
ELM-TFS-14 Traffic Signal
Working assessment: this pattern’s status reflects a preliminary Commonway System judgment call, pending final review.
#Why this pattern exists
Above a certain volume or conflict complexity, an uncontrolled or sign-controlled intersection can no longer safely and efficiently sort competing movements; a traffic signal imposes timed, positive control over who moves when. This pattern exists to document signal use as a documented departure from Commonway System’s roundabout-default intersection treatment, requiring its own justification.
#Key considerations
- Consistent with Commonway System’s intersection defaults, signal installation should require documented burden-of-proof justification rather than being a default choice
- Timing and phasing should account for all modes present, not just vehicle throughput; pedestrian and bicycle phases need adequate crossing time
- Signal coordination along a corridor affects speed and platooning behavior well beyond the single intersection where it is installed
#Related patterns
Roundabout (INT-RAB-01) (the CS default this pattern is a documented departure from); Pedestrian Signal (ELM-PDS-15), Bicycle Signal (ELM-BCS-16) (companion signal types at a signalized intersection)
Unsourced claim
Formal citations for this pattern have not yet been compiled from primary sources.