Bridge 105 MSL – Replacement, South Canterbury

Date: December 2014 – March 2015

Client: Kiwi Rail

Engineer: Novare Design

Main Contractor: McConnell Dowell

PT Subcontractor: BBR Contech

KiwiRail’s vision of providing a world class freight and passenger service for New Zealand, means maintenance and improvements to the rail network are an essential element. Bridge 105 is a steel and timber construction that crosses the Otaio River 2km south of St Andrews but the 106 year old timber substructure had deteriorated significantly forcing a decision to replace the existing bridge with a new 126m long concrete structure.

The replacement bridge construction features concrete beams and columns with 9 x 14m precast concrete deck span units. Construction Techniques Ltd was employed to provide post tensioning services for the new design which incorporates BBR CMI multi strand tendons in the precast deck units.

A total of 108No. BBR CMI 0906 multi strand tendons with UTS of 2,250kN per tendon were installed. Each precast unit had 12No. tendons tensioned to 77% UTS with 10 tendons running straight along the bottom of the unit and a parabolic tendon to the upstand either side.