Geomatic Technologies completes Ontrack AIMS Laser Survey

Melbourne, Australia 2007 – Geomatic Technologies (GT), has successfully completed two urban network structure gauge encroachment surveys on behalf of Ontrack New Zealand.

Ontrack, state-owned owners and managers of NZ rail infrastructure recognised that network expansion and capacity planning would benefit from a laser structure gauge survey and this year GT have completed such services over the Auckland (130 track miles) and Wellington (160 track miles) networks.

GT staff mobilised a narrow gauge hy-rail vehicle provided by Ontrack with the AIMS (Asset Inspection Mapping System) that was configured with high-speed reflectorless lasers. The lasers scan continuously, recording distances to objects within line-of-sight of to a range of 8m from the track centreline.

Each laser emits a “fan” of rays at high speed as the project vehicle is driven along the track. The lasers have a range of 8m and are able to detect all features that might encroach into the corridor envelope. As the lasers complete their sweep cycles the combined data stream is saved to disk and stored as a single complete profile.

Profiles were referenced to other systems on the AIMS recording vehicle that measure the vehicles’ location and orientation to allow each profile to be geo-referenced to the track alignment during post-processing.

A special low lux digital black and white camera was installed on the hy-rail to allow the identification of network features. To support the structure gauge survey GT’s AIMS data was post processed through a Kalman Filter and Curve Fitting algorithms to detect the track alignment straight, curve and transition sections.

After processing approximately 2.5 million laser profiles throughout the Auckland track network GT detected several hundred structure gauge encroachments that were of interest to Ontrack. The vast majority of these were due to vegetation however there were several instances where existing platforms, bridges and tunnels needed to be assessed against future freight and rolling stock requirements. An example with the corresponding day-time imagery is included below.

GT staff and resources completed the Auckland project within a very tight two month project timeframe and the field system was subsequently deployed to capture data over the Wellington network.

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