Intelligent Driver Model · MOBIL lane changes

PHANTOM JAM

A closed loop of road. No accidents, no bottleneck of any kind. Tap one driver on the brakes and — if the road is dense enough — watch the disturbance refuse to die, instead crawling backwards around the ring forever as a stop-and-go wave. Switch to the figure-eight to add the one thing the ring lacks: a junction where the two arms genuinely have to take turns.

CLICK ANY CAR TO MAKE IT BRAKE HARD
Mean speed
0km/h
Flow
0veh/h
Jammed <15
0
Slowest
0km/h
Density
0/km/ln
Space–time diagram↓ 60 s of history
0 mposition around the loop →1000 m
Each pixel row is one instant; each coloured streak is one car's trajectory. Cars drift right as time runs down. A jam shows up as a dark band leaning the other way — the congestion travels backwards through the traffic at about 13 km/h, even though every car caught in it is still rolling forwards at nearly three times that.