traffic jam

noun

1. A situation in which road traffic accumulates until it is stationary or very slow.

   “Victorian Londoners did not speak of 'traffic jams' - that term came from America after the First World War. They spoke rather of traffic 'locks' or 'blocks', and their prevalence would be one reason why Pearson began to direct his thoughts underground.”

   “Driving in London next week ? Then watch out for the big traffic-jam spots – the places where you may well face a wait if you cannot go another way.”