Gridlock refers to a traffic jam where a network of intersecting streets becomes so heavily congested that vehicles cannot move at all.
"The meaning of GRIDLOCK is a traffic jam in which a grid of intersecting streets is so completely congested that no vehicular movement is possible."
Gridlock happens when traffic backing up on one street blocks traffic on cross streets, causing a standstill in all directions. This situation often occurs in busy urban areas during peak hours.
Author's summary:
Gridlock describes a severe traffic situation where vehicles are stuck in a complete standstill due to obstructed intersections within a city's street grid.