Purewa Tunnel Drainage Upgrade And Track Lowering, Auckland, New Zealand

Client: KiwiRail
Timeframe: 2010
Total value: $3m

Components: Drainage upgrade and track lowering in railway tunnel

Project description:

Purewa Tunnel is an 800m long concrete-lined rail tunnel on the North Island Main Trunk Railway (Eastern Line) in Auckland, New Zealand. In past years the tunnel has experienced significant water drainage issues. This project aimed to address those issues, while also lowering tracks within the tunnel to allow the required clearance required by the Auckland railway electrification programme.

Our role

Xigo was contracted by KiwiRail to handle procurement of the designer and contractor; management of the design and consent process; preparation and facilitation of reviews of project reports to the KiwiRail management team on track lowering options and associated costs; and project management during the three-week construction phase.

Main challenges

  • Working closely with KiwiRail to establish the tunnel clearance requirements of rolling stock
  • Numerous iterations of project plans were required to balance the cost of additional track lowering against the associated benefits to the rail business
  • This high-intensity project culminated in a short delivery phase – all work needed to be completed during a three-week shutdown of the rail corridor
  • Two kilometres of track had to be removed from the site and replaced with new components on a new foundation constructed at a lower level than the existing track
  • To meet the deadline, the programme required around-the-clock work for the entire three week period

Our approach

Significant advance planning was required to ensure work could be successfully completely during the three-week shutdown of the rail corridor. We conducted numerous risk reviews, investigated detailed options for site access, and assembled a number of design constructability reviews. During the construction phase of the project a Xigo project manager, an engineer’s representative and a client representative were on site at all times.


The Purewa tunnel project was one of the highest risk projects of about 30 KiwiRail had to complete during the Christmas 2010/11 rail corridor shutdown. Giving the all-clear for trains to run again at the end of the three-week period was a huge achievement for all parties. No significant safety incidents occurred during the constructions phase and works were delivered significantly below budget.