Two new SH1 structures were needed to cross the Moutoa Floodway and Manawatū River to replace the existing Whirokino Trestle, which was coming to the end of its life, and the Manawatū River Bridge.

Brian Perry Civil’s planning and risk management skills ensured the 680m Whirokino Trestle and 200m Manawatū River Bridge were completed ten months ahead of the original schedule. A wide range of BPC’s specialist ground engineering techniques were required due to the extremely long structure being founded in many variable soils.

One hundred and fifteen continuous super tee beams were made in BPC’s Otaihanga precast yard and installed on the river by one of the country’s largest (600T) crawler cranes. BPC’s in-house geotechnical expertise was employed for work in the floodway and river channel through a smart innovative temporary works design to facilitate the safe execution of the work.

Prioritising stakeholder engagement helped mitigate some significant risks that came with the project. The team worked closely with Horizons Council on the flooding risk, and trusted relationships were built with local iwi, who had representatives on site whenever topsoil was being stripped.

Environmental awareness was also instilled in the crew and engaged an ecologist to help protect the area, including relocating eels to a safe site before any backfilling.