Bridges No.37 - M3 Motorway Bridge

The bridge carrying the M3 over the Thames is the first motorway bridge you encounter when travelling upstream, a short distance from Chertsey Bridge and Lock. The M3 bridge is a cantilever bridge and was built in 1971 to a design by Posford, Pavry & Partners with Courtney Theobald acting as consulatant architects. It is built from high tensile steel. Although a single structure with a uniform design, the two carridgeways of the motorway are carried on separate sections and are at slightly different heights. The downstream deck was brought into use first in 1970, with the upstream deck being used from March 1971 when the bridge was completed. However, the bridge forms part of the motorway that was not fully opened until 1974. The original section of the M3 ran from junction 3 (Bagshot) to junction 8 (Michedever). The London bound extension to junction 1 was opened in 1974.