Rakaia Bridge

Rakaia Bridge
Rakaia Bridge (State Highway 1) is New Zealand's longest road bridge
Coordinates	43°44′38″S 172°02′16″E / 43.7440°S 172.0378°E / -43.7440; 172.0378Coordinates: 43°44′38″S 172°02′16″E / 43.7440°S 172.0378°E / -43.7440; 172.0378
Carries	road traffic
Crosses	Rakaia River
Locale	Canterbury
Other name(s)	Rakaia Road Bridge
Named for	Maori name of the river
Owner	NZ Transport Agency
Characteristics
Design	simply supported reinforced concrete spans
Material	concrete
Total length	5,762 ft (1,756 m)
Width	20.5 ft (6.2 m)
No. of spans	144
History
Designer	Public Works Department
Constructed by	Rope Construction
Construction start	March 1937
Inaugurated	25 March 1939

The Rakaia Bridge is New Zealand's longest road bridge and crosses the Rakaia River, one of Canterbury's large braided rivers. The present bridge was opened in 1939 and replaced an earlier combined road and rail bridge from 1873. The present road bridge is just downstream from the rail bridge and forms part of State Highway 1.

The Canterbury Provincial Council decided in April 1864 to commence building the railway from Christchurch to Timaru. An engineer was engaged to undertake the design for the bridge over the Rakaia River and to proceed with construction immediately. Construction of the railway commenced, but there were problems with funding and the Rakaia Bridge was not started. By the time the line reached Selwyn in October 1867, 35 kilometres (22 mi) from central Christchurch and just across the Selwyn River, the provincial government was so short of finances that construction was temporarily halted. The provincial government called for tenders for a road bridge over the Rakaia River and awarded the contract on 17 October 1869 to William White, who had earlier built a bridge over the Waimakariri River. White was to construct a timber bridge with 96 spans of 12.2 metres (40 ft) each. Much of the timber was cut in Little River and barged across Lake Forsyth and Lake Ellesmere / Te Waihora. Worked ceased in the following year when it was decided to make the bridge a combined one for both road and rail traffic. A second contract was tendered and again won by William White.

The Christchurch engineer William Bayley Bray (1812–1885) suggested that the spans could be reduced to 6.1 metres (20 ft), to which the provincial council agreed. John Blackett peer reviewed the plans on behalf of central government and recommended transverse joists and longitudinal planking. The contractor instead recommended transverse planking directly onto the girders with a 127 millimetres (5.0 in) asphalt cover, to which the provincial engineer agreed. The bridge was completed on 16 April 1873, but without the handrail being in place yet. The formal opening of the bridge was on 29 May 1873 by the superintendent of the Canterbury Province, William Rolleston. All but four of the provincial councillors were present, plus a number of central government ministers and members of parliament, including William Hunter Reynolds (Commissioner of Customs), John Bathgate (Minister of Justice), Edward Stafford, William Montgomery, William Sefton Moorhouse, George Leslie Lee, Hugh Murray-Aynsley, Walter Kennaway, Col De Renzie Brett, Henry Tancred, and Ernest Gray. The bridge cost NZ£36,196, was 17 feet 3 inches (5.26 m) wide, and 4,480 feet (1,370 m) long. The rail was put down in broad gauge, 5 feet 3 inches (1,600 mm), as was the initial standard gauge in Canterbury.