Researchers from Monash University have used lessons learnt by metro engineers in Hong Kong to solve the dilemma of light rail noise on the Gold Coast.
While light rail systems can enhance the functionality of urban areas by bringing cheap and convenient transportation to visitors and local denizens, they can also have a highly detrimental impact on the quality of life for nearby residents due to the noise pollution they produce.
Acutely aware of this problem, the designers and builders of the new Gold Coast light rail passenger service (GCLR) have sought the help of engineers from Monash University to deal with this dilemma.
The GoldLinQ consortium sought the assistance in particular of Ravi Ravitharan, director of Monash's Institute of Railway Technology (IRT) who in turn looked to the lessons learnt by rail engineers in Hong Kong when dealing with the shrill noise emissions of its train systems.
"Railway noise emissions are often a significant concern to residents living adjacent to railway tracks, particularly during the night hours," said Ravitharan. "Wheel squeal and flanging noise are often the main cause of annoyance to residents as the high pitch screeching is generally found at the high frequency end of the audible noise spectrum."
This problem was evident early on in the GCLR project, with local residents living close to the tracks of the rail making complaints to GoldLinQ about noise levels during the period of trial operation.
In order to address this problem, Ravitharan first looked at studies undertaken in Hong Kong that sought to ascertain the precise cause of wheel squeal in rail systems.
Those studies found wheel squeal is directly related to the nature of the friction that arises between the train and rail when traversing sharp curves at slow speeds.
Equipped with a better understanding of the causes of noise pollution, Ravitharan was able to devise more effective methods for remedying the problem.
"Through the research we were able to identify lowering the adhesion limit was an efficient way to control creep forces and energy dissipation in order to eliminate squeal noise," he said. "By modifying the friction characteristics at the wheel-rail interface using specialised lubricants, wheel squeal and noise was completely eliminated during trials carried out on the GCLR network."
Other measures adopted by IRT included the use of friction head modifiers at key parts of the light rail line in Surfers Paradise, which served to significantly reduce noise pollution for adjacent areas.