Traffic

Rotary vs Traffic Signal — Quick Decision Tool

Enter site data (peak-hour flows, pedestrians, accidents, space, etc.). The tool uses simple IRC-inspired thresholds and weighted scoring to suggest a preference.

Number of approaches 3 4 5 6+

Peak hour entering volume — Major arm (vehicles/hour)

Peak hour entering volume — Minor arm (vehicles/hour)

Percent right-turns (average across approaches) %

Peak pedestrian crossing flow (pedestrians/hour)

Reported accidents last year (count at junction)

85th percentile speed on major approaches (km/h)

Available central island diameter (clear space) (m) — set 0 if none

Is the traffic distribution roughly balanced across approaches? YesNo

Is the available right-of-way / space limited? NoYes If space is limited signals generally perform better than large roundabouts.

Notes / Site constraints (optional)

Rotary score

Signal score

Decision logic details

This is a decision *assistance* tool. It uses simplified rules inspired by IRC guidance (roundabout suitability ~ balanced flows, moderate volumes; signals when pedestrians/accidents are high or space is tight). For final design apply full IRC codes and local engineering judgement.