This page outlines the history and description of the bridge carrying Airlie Road over the Main Trunk Railway, just south of Whenua Tapu Cemetery on state highway 1.
Airlie Road bridge.
Photo – Russell Murray, 2007.
This bridge has now been replaced with a new concrete structure.
This bridge appears to have been built in 1937 in tandem with the track duplication work on the Main Trunk Line, replacing an earlier timber bridge (over the original single track) that had been built in 1912. The original bridge, and its replacement, afforded continuity of traffic over the rail line in an area where a level crossing would be difficult to form. The bridge is a late example of a timber Howe truss bridge; from the 1930s onwards timber structures were quickly supplanted by more efficient and durable concrete and steel structures for railway and road work.
The bridge was replaced in the second half of 2010 with a reinforced concrete bridge. The replacement was required because the Airlie Road bridge was at the end of its operational life, and may posed a hazard to the NIMT line if it was not replaced.
A local legend of the “Black Bridge” seems to have arisen from a notion that the bridge was sufficiently low to decapitate incautious trainmen. However, the bridge would have been built to normal railway clearances of the day and there is no information to hand to substantiate this legend.
The bridge was a single lane road bridge spanning across the rail line and has three spans consisting of a simply supported approach span (approximately 14’ (4.2 m) long each) on either side of a Howe truss main span approximately 38’ (11.5 m) long, with timber piers to support the common landings of the spans and concrete abutments at either end with a timber beam.
See also the Historic site: Airlie Road Overbridge page under the Porirua's Suburbs: Plimmerton section of this website.
Built By Optimation