Grey District Council needed to replace two old and unsafe bridges on Atarau Road. Both were undersized single lane bridges not rated to take oversize/overweight vehicles and had a poor history of traffic accidents (over/through the guardrail). Isaac Construction provided full end-to-end involvement through the tender, design and construction phases. This project also called on the unique skills of Liddell Contracting.
Liddell Contracting has constructed a completely re-usable bridge design and steel formworks that can be rapidly deployed for similar bridges in the region. Both the Rough River and Moonlight Bridges were able to use this same design, with only span length, pier heigh and pile depth varying between projects. This solution will be very cost-effective for the ongoing campaign to modernise and upgrade key bridges throughout the district.
The new bridges are both HNHO rated with two lanes and a design life of 100 years. Both were shortened to decrease the overall cost and have been designed to withstand 50 and 100-year floods without structural damage. Now with two lanes, local farmers can run their operations with fewer restrictions (e.g., for over-weight and over-size vehicles during harvest operations.
Environmental requirements were managed in accordance with Grey District Council, West Coast Regional Council, Fish and Game and DoC requirements; several visits were undertaken and no required actions as a result.