bottleneck
[noun]
Synonyms: hold-up, block, blockage, congestion, impediment, jam, obstacle, obstruction, snarl-up (informal, chiefly Brit.)

[TahlilGaran] English Synonym Dictionary ▲

bot‧tle‧neck /ˈbɒtlnek $ ˈbɑː-/ noun [countable]

1. a place in a road where the traffic cannot pass easily, so that there are a lot of delays

2. a delay in one stage of a process that makes the whole process take longer:
Understaffing has caused a real bottleneck.

[TahlilGaran] Dictionary of Contemporary English ▲

bottleneck
n. A heavy traffic congestion.
In Chicago the worst bottleneck is found where the Kennedy and the Eden's expressways separate on the way to the airport.

[TahlilGaran] English Idioms Dictionary ▲