Gridlock occurs when vehicles enter intersections without enough room to clear them before the light turns red, blocking cross-traffic. This creates a cascading failure across a city grid where no one can move because each stream of traffic blocks another. Resolving it usually requires police intervention to manually clear intersections one by one.
Heard on the job
A broken signal on 5th Avenue caused a backup that threw the entire downtown into gridlock for two hours.
Related terms
Traffic jam
A severe congestion event where vehicle movement slows to a crawl or stops entirely.
Phantom jam
A traffic bottleneck that forms on a highway without any physical obstruction or crash.
Clearance time
The duration required for an intersection or road segment to empty of traffic before conflicting movements begin.