KiwiRail, Auckland New Zealand

KiwiRail extracts multiple uses from single laser clearance survey

Business Challenge

KiwiRail (formerly ONTRACK) owns and manages New Zealand’s rail network on behalf of the New Zealand Government, maintaining 4,000 kms of railway track, bridges and tunnels.

Auckland’s rail network is being upgraded to enable more frequent and reliable commuter services, and to prepare for its electrification in time for the delivery of Auckland’s new electric trains in 2013.

KiwiRail had concerns about the potential impact on existing overbridges of the planned electrification and the introduction of the new electric powered rolling stock. The concern was that some overbridges could be too low to accommodate the extra clearances required for these initiatives.

KiwiRail’s initial concern was to determine the extent of the problem before taking any further action. KiwiRail turned to Geomatic Technologies (GT) for help.

Services Overview

Some months prior to KiwiRail’s request GT recorded approximately 2.5 million laser profiles over 212 km of track in a one week recording period. This was done to test the compatibility of a new locomotive, the Siemens Asiarunner, with the Auckland network.

GT had used its GT’s Asset Inspection Mapping System (GT AIMS) installed on a KiwiRail hyrail to undertake the survey. GT AIMS is a technology platform that can be configured for a wide range of mapping needs and can be installed on a range of vehicles.

GT used the previously recorded laser data to determine which overbridges would be affected by both the electrification project and the new electric powered rolling stock. This was done by passing a KiwiRail tall narrow vehicle kinematic envelope through the recorded data to see where the envelope ‘hit’ an overbridge.

For each offending overbridge a longitudinal section was prepared covering around 800 metres of track leading up to and following the overbridge in question. The longitudinal section also included digital stills and laser profiles at locations just prior to, underneath, and just after each overbridge.


–  Using GT AIMS KiwiRail was given a comprehensive understanding of the number of problem  overbridges it had on its network in a much quicker and cost effective fashion than using  conventional survey teams on-site.

–  Previously recorded laser data was reused for determining the impact of further planned  improvements (both infrastructure and rolling stock) on the Auckland rail network thus
increasing the return on investment for the original laser survey.

–  The laser data also proved to be a useful input into the development of more detailed plans to  assess the modification potential of tunnels on the Auckland network due to changing rolling  stock requirements.