The measurement of train noise: a case study in northern Italy

This paper analyses the interactions between vehicles, infrastructure and environment for rail traffic. It identifies variables having a significant influence on sound levels, defines a standard procedure for measuring noise, and develops a database for setting up and calibrating train noise models. A pilot study looks at two railway lines passing through Vercelli, a medium sized town in the north-west of Italy. Four main conclusions were drawn. First, in certain conditions, variables that normally influence noise production can be neglected (e.g. when surrounding environmental conditions are constant, different types of train do not cause a significant variation in noise level). Secondly, when diesel trains are travelling at less than 70 km/h, a speed change of 30–40 km/h significantly affects the maximum noise level (Lmax). However, for electrified lines, when speed is below 80 km/h, a change of 20–30 km/h does not cause significant variations in Lmax. Thirdly, for diesel trains transiting at low speeds––e.g. near stations––noise emissions are strongly affected by acceleration/deceleration. Lastly, an approach based on ‘sites types’ is able to produce useful results because site configuration and the presence of building significantly affect Lmax. High buildings along the line can increase noise levels and may nullify the advantages derived from technological advance in the vehicles.