Briony Croft
Acoustic Studio Pty Ltd

Over a year’s vibration data was collected adjacent to the rail corridor in Sydney. Vibration from one train type (Tangara trains) travelling on the track nearest to the vibration monitor was observed to be 5 dB higher on average than the vibration produced by newer generation Waratah trains. This was a surprising result, since the two train types are similar in many respects that are commonly recognized to contribute to ground vibration generation – for example, the difference in unsprung mass between the train types is just 10%.

Examination of the dataset and review of wheel impact load detector records revealed that these trains experience a much higher incidence of wheel flats than newer generation train types operating on the system, resulting in increased noise and vibration. This presentation describes the outcomes of investigations to understand the root cause of the higher Tangara train vibration levels, considering maintenance factors as well as vehicle design factors: the effects of unsprung mass, suspension stiffness, wheel metallurgy, wheel-slip protection and traction control systems.