Octa was engaged as Engineer to the Contract by KiwiRail for this infrastructure replacement project. Octa’s engagement commenced mid-2013 and wrapped up in February 2016 with the completion of the third stage of the project.
The project involved constructing 989 No.700mm diameter reinforced concrete foundations, installing new mast and cantilever support structures for the 30 km of NIMT double track between Redwood and Muri, Paekakariki and McKays Crossing as well as Tunnels 1 and 2, and replacing new copper overhead wiring as well as new trenched communications cabling. The majority of the work was undertaken at night between train movements and during scheduled rail closures of the NIMT.
The work was delivered to programme and significant savings were achieved through a number of contractor initiated innovations. The successful contractor was an international joint venture and the contract was developed around a modified NZS 3910 General Conditions of Contract using cost reimbursement with a Target Outturn Cost mechanism. A pain/gain mechanism was used to incentivise cost savings through innovation as well as annual performance payments through defined Key Performance Indicators.
Over 285,000 man hours of labour were expended with an exemplary safety record. A significant number of variations were able to be added to the contract due to the performance and competence of the project team.
The project incorporated a number of innovations which had not previously been used in New Zealand. These included the use of twin-track cantilever support structures which significantly reduced the number of mast foundations and reduced the overall cost as well as the number of man hours needed. Fibre reinforced concrete was trialled and then incorporated into mast foundations, again reducing the cost of each foundation.