Transit Signal Priority — Bus Green-Extension Simulator (2D)

This simulator models transit signal priority (TSP), the traffic-control technique cities use to keep buses moving through congested corridors: a bus approaching a signalized intersection checks in with the controller, which conditionally extends the green it is already receiving or pulls the green forward early, always inside a protected minimum-green envelope so the cross street is never starved. A full two-phase intersection runs real kinematic car-following and braking physics on all four approaches, rendered as a top-down live map with a scrolling phase-timeline strip chart underneath, so the trade-off between bus delay and cross-street car delay is measured live rather than assumed — toggle priority off to see the same traffic run a plain fixed-time cycle instead.