Rakaia Bridge, Road bridge in Canterbury, New Zealand

Rakaia Bridge is a reinforced concrete road bridge carrying State Highway 1 over the Rakaia River in Canterbury, New Zealand. Opened in 1939, it was designed by the Public Works Department under Fritz Langbein and built by the Rope Construction Company. It has 144 spans of 40 feet (12 m), giving a total length of 5,762 feet (1,756 m).

The current bridge was constructed between March 1937 and March 1939, replacing an earlier combined road and rail structure from 1873. The newer design was needed to accommodate growing traffic demand and to separate automobile traffic from rail transport.

The bridge is named after the Rakaia River, one of Canterbury's large braided rivers. Its 1939 opening was organised by the Canterbury Automobile Association, and H. C. Harley of that association spoke at the ceremony alongside Minister of Public Works Bob Semple and local MP Arthur Grigg.

The bridge has two lanes and carries regular through traffic, so it is best crossed during off-peak times to avoid congestion. Clear signage on State Highway 1 makes navigation straightforward, and nearby viewpoints offer opportunities to observe the river landscape.

The 1939 bridge is New Zealand's longest road bridge, not the Southern Hemisphere's; the rail bridge just upstream, opened the same year, is the country's longest rail bridge at 1,740 metres. The old combined bridge's last train crossed on 12 December 1939.