Bridges

As part of the ongoing upgrade of timber-piled bridges on the North Island Main Trunk, KiwiRail identified three bridges (BR 280, 281, 282) to be replaced in 2012. These bridges all cross streams of 16 m to 42 m in width and provide a ballast deck for twin rail lines. A collaborative approach was undertaken with an Early Contractor Involvement contract bringing the consultant, the contractor and KiwiRail together to develop a standard design for all bridges using precast prestressed concrete girders in a unique application for rail works. To allow all 3 bridges to be completed within a single 3-day rail closure an innovative construction sequence (to slide the decks into place) was successfully developed. Key areas of success included:• Developing effective access and temporary works designs.• Fast tracking of the project delivery to meet the Christmas rail closure by using an accelerated design and consenting process.• Development of an innovative solution using precast concrete girders.• Design of piled foundations for poor ground conditions.• Careful attention to safety at the concept stage to design out the risk in working in the rail corridor.