Rangiriri rail bridges, New Zealand

As part of the ongoing upgrade of timber piled bridges on the North Island Main Trunk (NIMT) 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 (ECI) contract bringing the consultant, the contractor and KiwiRail together to develop a standard design ( refer figure 1 ) 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.