The Waimakariri District Council is working with the Selwyn District Council and Waka Kotahi New Zealand Transport Agency on a $3 million project to replace decking on the bridge.
Roading and transport manager Joanne McBride said the decking has suffered deterioration to the point where it urgently needs replacing.
The bridge is jointly owned by the two councils, with the Selwyn council responsible for maintaining the bridge.
The two councils and Waka Kotahi have been working with structural consultants Beca on the design and tender for the deck replacement.
Ms McBride said the councils hoped to award the tender next month and complete the project early next year.
The replacement decking would be timber plywood paneling with an epoxy chip seal surface and the existing handrail will be replaced with a vehicle compliant barrier and handrail system.
The work was expected to take five weeks, with residents to be advised of any restrictions.
‘‘Failure to replace the deck could result in the restriction of movements across the bridge, which would impact those who use it regularly,’’ Ms McBride said.
‘‘The alternative detour is about 115km long and would add about one hour 15 minutes to the journey.’’
The alternative route meant taking the State Highway 1 bridge or the old Waimakariri bridge, south of Kaiapoi.
The co-funding agreement meant Waka Kotahi’s contribution was 51 percent, with the two councils each contributing 24.5%.
The original Waimakariri Gorge bridge was built in 1876 by Williams Stocke.
Until the 1930s it carried the Oxford-Rangiora-Sheffield railway line.
It was later modified and repurposed to allow vehicles to cross.
The decking was last replaced in 2011, with timber baulks across the main structure and new concrete deck panels at each abutment.
By David Hill, Local Democracy Reporter
■ Public interest journalism funded through New Zealand on Air.
