Public Transport Victoria, Victoria Australia

Tram survey highlights tight locations on tram network and delivers accurate kinematic outline for future tram purchases

Business Challenge

Public Transport Victoria (formerly Department of Transport) or PTV is the statutory authority responsible for public transport, roads and ports across Victoria.

As part of a new tram procurement program for the Melbourne tram network, the PTV needed to provide tenderers with a kinematic outline. This outline was needed to inform tenderers on what the maximum design limits would be for any new tram design in consideration of the existing network infrastructure (platforms, etc) and existing tram rollingstock. PTV turned to Geomatic Technologies (GT) for assistance.

Services Overview

Using GT’s Asset Inspection Mapping System (GT AIMS), GT undertook a survey of the tram network. The first stage involved identifying a number of ‘tight’ locations on the network. This typically included 90° bends around street corners and also included some corners that had severe gradient changes.

Once the tight locations had been identified, each location was field surveyed over a length of 200 to 300 metres to establish an accurate 3D track centreline with curve radii and grade.

The second stage involved modelling kinematic impacts with the existing rolling stock fleet. To do this an analysis of each of the nine unique tram bodies operating on the Melbourne network was needed.

This analysis was conducted by slowly driving each tram body past a fixed laser scanner on a 270° sweep at 1/2° increments, generating 27,000 points per second to create a detailed 3D point cloud profile.

This particular method was selected as it was deemed superior to just using engineering drawings. It captured all external details of the tram, including the ‘sky breaker’ advertising boards that had been fitted to the trams after they were built.

GT AIMS software was used to process vehicle kinematic factors (vehicle bounce, wheel and rail wear, pivot point height, superelevation) and factor in the lateral displacement and sway of the vehicle on curved track.

The results of stages 1 and 2 were combined to produce a maximum dynamic vehicle outline that varied based on instantaneous track geometry. The analysis demonstrated that critical locations on the network were in the inner city, where W-Class trams had the potential to come into contact other trams.

Outcomes

–  The survey established that clearances were adequate for the current tram fleet.

–  The kinematic outline was made available to tenderers and provided a high level of confidence  that any tram design put forward would fit the tram network.

–  A kinematic outline was now available to guide future tram purchases.

–  The survey provided an improved knowledge of locations where there was potential for trams  to come into contact with each other.

–  The survey provided an improved knowledge of tram handling characteristics.