Yarra Trams, Victoria Australia
Track geometry survey leads to improved knowledge of track condition, lower tram procurement risk, and improved employee safety on the world's largest tram network
Yarra Trams is a fully owned corporation of the Victorian State Government and is responsible for the largest tram network in the world with 480 km of track consisting of 28 major routes across Melbourne. Every week this system runs 31,400 scheduled tram services.
Operations are run on a franchising model. Prior to seeking expressions of interest on a new franchise agreement, Yarra Trams sought an ‘up-to-date’ picture of network configuration and condition. With mounting world-wide interest in the franchise, there was only a small window of opportunity available to obtain this information.
Relying on its existing resources would mean that Yarra Tram’s track inspectors would have to walk and visually inspect each track section, as well as take manual measurements of various track parameters. This would be hazardous as it would have been done while trams were running. It would also be labour intensive, and inspectors would be limited in the amount of track they could inspect on a given day. It was clear that a better solution would have to be found.
Geomatic Technologies (GT) was asked by the Department of Transport to conduct a tram track ride quality and geometry assessment. A B-Class tram was fitted with a series of accelerometers to record both sprung accelerations (ride quality) and unsprung accelerations (the rail side impact on the vehicle). The ride quality parameters for passenger ride comfort were guided by ISO 2631 (Mechanical Vibration and Shock) standard.
Parallel to this, GT used a track geometry measurement system to deliver gauge, top, line, cant and twist data. All geometry exceedant values and index calculations were referenced to the correct track kilometrage and alignment. This was the first time such a comprehensive survey had been conducted of Melbourne’s tram network.
The survey was conducted over ten nights to minimise the impact of traffic on the tram and to release the tram for passenger service during the day.
From this survey GT identified, field checked and photographed hundreds of track related defects of various priorities in the tram network.
- GT conducts six monthly surveys to provide a condition assessment and analysis of system degradation over time.
- KDR Melbourne, the current franchisee, utilises the survey data to assign priorities for track maintenance.
- The condition data allows Yarra Trams to tightly specify operating conditions for new trams so that manufacturers can see if their trams meet the physical conditions of running on the Melbourne network.
- Track inspectors enjoy improved levels of safety due to reduced manual measurements of track geometry.