Collocations for congestion - noun

chronic, serious, severe
increased, increasing
highway (AmE), road, traffic
the nation's dependence on cars and the resulting highway congestion
Parking near the school causes severe traffic congestion.

downtown (AmE), urban
a study of downtown traffic congestion

Internet, network
Engineers are hoping network congestion will become a thing of the past.

chest, nasal

cause, lead to
alleviate, avoid, ease, minimize, reduce, relieve
measures to ease the increasing congestion in Hong Kong

increase, worsen

charge, pricing (both BrE)