The Birkenhead Bridge is a bascule bridge in Adelaide, Australia that crosses the Port River. In February 1938, the Government of South Australia awarded a contract to Adelaide Construction to build a bridge across the Port River from Birkenhead to Port Adelaide, with Perry Engineering contracted to supply the steelwork. The bridge was opened on 14 December 1940 by Governor Malcolm Barclay-Harvey. It was one of only four bascule bridges in the world adapted for use by trolleybuses. The bridge is listed on the South Australian Heritage Register.