North Island Main Trunk 439km Improvements

KiwiRail identified a high-risk slip on the North Island’s main trunk 439km from Wellington so Vitruvius partnered with T&T and the client to optioneer a long-term solution which would provide slope stability and the required level of resilience.

Each option had a different cost and risk profile. Following the option assessment process, we then developed the preferred option through to the detailed design and construction phase. Vitruvius led the strategic procurement for the physical works, as well as the rail infrastructure and drainage design. This included a hydrological assessment and stormwater design, including a large box culvert and erosion protection works for multiple discharge points.

We then provided on-site construction reviews to ensure application was as per the design.

Vitruvius helped deliver and implement a monitoring strategy of the high-risk slopes which included the installation of remote tilt sensors. This was a good application of existing technology to provide KiwiRail with an early warning of any slip potential. The site was remote, so it also gave the client assurance while design and procurement was underway for the main remedial works.