The Avonmouth Bridge is a road bridge that carries the M5 motorway over the River Avon into Somerset near Bristol, England and it was opened in May 1974. The main span is 538 ft (164 m) long, and the bridge is 4,554 ft (1,388 m) long, with an air draught above mean high water level of 98.4 ft (30 m). It also contains a separate bridleway for foot passengers, bicycles and mopeds.
The bridge was built with three lanes each way, with full hard shoulders. During 2002–2004, it was widened to four lanes each way, resulting in the hard shoulders no longer being of full width.
The bridge was built to allow tall ships underneath. This gave the bridge steep gradients that cause heavy vehicles to slow down, resulting in congestion during rush hour and the summer tourist season: traffic can stack up both on the bridge and on the approaches.
The approach and initial climb up the bridge have a smooth asphalt surface, however on the top of the bridge the surface is uneven and bumpy. In September 2006, it was announced that the entire bridge would be resurfaced, only five years after that had last been completed.