Frid A., Ognar M.

The noise from rail and road traffic in urban areas is a major issue in many European cities. This topic is dealt with in the ongoing 6th framework EU-project “Silence” (ref TIP4-CT-2005-516288). In an urban context noise from trams is one component in the overall picture that is potentially annoying for nearby residents unless properly dealt with. The noise characteristics of a tram and a train are quite different due to the substantial difference in design and construction both on the vehicle side and on the track side. In particular, the squealing noise when running through tight curves is a well-known problem mainly associated with trams. Also, in tram networks there are often many crossings and switches, which will cause increased noise. The T3000 low floor tram represents the state-of-the-art in its class and was delivered to the city of Brussels in October 2005. It is equipped with resilient wheels and modern traction equipment. The present work reports a detailed acoustic analysis carried out on the T3000 tram within the above mentioned EU-project “Silence”. A detailed identification of acoustic sources has been made using a combination of numerical calculations, laboratory experiments and full-scale stationary and running tests with wayside microphones and onboard microphones and accelerometers. The tests have been performed both on a dedicated test track and in selected “hot spots” in the Brussels city network. Wheel-rail noise has been derived using the TWINS prediction software with measured wheel and rail roughness as input. Noise from equipment such as the traction motor, gearbox and ventilation units has been measured in laboratory and in-situ on the vehicle. Resulting from the source ranking exercise, a global prediction model has been set up in which the benefit of applying different noise mitigation measures such as bogie covers, wheel absorbers, etc has been quantified.