Each car is driven by the Intelligent Driver Model (IDM), a standard car-following equation used in real traffic microsimulation. Acceleration depends on how far the car is from its desired speed and on the gap to the vehicle (or red light) ahead:
s* = s0 + v·T + v·Δv / (2·sqrt(a·b))
dv/dt = a · [ 1 − (v/v0)⁴ − (s*/s)² ]
s0 is the minimum bumper-to-bumper gap, T is the desired time headway, v0 the free-flow speed, a/b the comfortable acceleration/braking. A red light is treated as a stationary "phantom car" sitting on the stop line, so approaching traffic brakes smoothly instead of teleporting to a stop.
- Autonomous share — self-driving cars use a shorter time headway and quicker reaction, tightening the queue and raising throughput.
- Signal cycle — the intersection alternates a horizontal-green / vertical-green phase, each lasting the slider's duration.
- Congestion — read off the ratio of the fleet's average speed to the posted limit.