这座桥是通往城市的唯一通道，成为了交通的瓶颈。

The bridge is the only access to the city, making it a major ___choke-point for traffic.

上下班高峰期，这座桥成了交通瓶颈，导致严重拥堵。

The bridge becomes a major ___choke-point during rush hour, causing heavy traffic jams.