A preliminary study of noise in a tunnel due to a moving train

Citizens travelling between cities and towns rely heavily on a mass transport system in many developed countries. In recent years, many more of these underground railway systems are constructed and expanded in many different cities. Though there have been significant reductions in the acoustical environment in automobiles and aircraft, train passengers are only recently starting to see improvements. The prime purpose of this preliminary study is to estimate the noise levels due to an underground train operating at different speeds in a tunnel. A simple experimental method is explored for measuring noise levels of a passenger train travelling in a tunnel in urban areas. This paper also attempts to study the reverberant sound fields when a train operates inside a tunnel - a long enclosed space. The result of the current study provides a guideline for design engineers in their future planning for constructing a new railway line and assists in supporting realistic contractual specifications. The experimental results can also be used as a guide to direct future efforts for reducing noise levels transmitted into the passenger compartments for an existing railway line.