thumb|right|300px|The Rakaia Gorge in flood

The Rakaia Gorge Bridge consists of two bridges, a single lane road bridge located on the Rakaia River in inland Canterbury in New Zealand's South Island known as the Rakaia Gorge Bridge No. 1, and a two lane concrete bridge over the flood channel known as the Rakaia Gorge Bridge No. 2. The bridge connects the Selwyn and Ashburton districts and carries State Highway 77 and the Inland Scenic Route. They are one of only two bridges crossing the Rakaia River, and the oldest, with the other being the Rakaia Bridge, carrying State Highway 1. Construction on the No. 1 bridge was conducted between 1880 and 1882 by contractors W. H. Barnes. It is listed as a category 1 historic place by Heritage New Zealand.

Description

The Rakaia Gorge Bridge No. 1 spans and features a wide timber deck and handrail on top of its iron girders and truss. The bridge is thought to be one of the earliest wrought iron bridges in New Zealand, and one of the few 19th century components of the New Zealand state highway network. In September 1985 the bridge was listed as a Category 1 Historic Place by Heritage New Zealand. Bollman wrote about the design: “This bridge has the advantage of great strength and perfect security, with very little weight of metal".

For many years, those in the New Zealand engineering community believed the No. 1 bridge to be a Bollman Truss, with the School of Engineering in Christchurch even teaching prospective civil engineers that the bridge followed this design. However, the No. 1 bridge differs from the works of Bollman in that the diagonal ties are anchored at each end by concrete-filled sockets that are tunnelled into the rock outcrops on which the abutments are placed.

References

  • View from Rakaia Gorge Bridge - Google Street View