The outcome of such an exercise usually results in production of noise contour maps of an averaged predicted noise level indicative of all noise sources throughout an inhabited area. The difficultly in what to do next with these maps is the subject of intense investigation. An area may be deemed to be exposed to too much noise, and then the sources of the noise must be deconstructed, the culprits identified and a decision made as to which source is to be ameliorated, and which are protected. Add into this process the ad-hoc mixture of noise regulations across member States, the demarcation of responsibilities when it comes to actual supply of noise control measures, and the difficulty in using whole city mapping as a planning tool.
With respect to rail noise in particular, experience in the United Kingdom highlights the hurdles that must be overcome. The UK railways were restructured and privatised as part of the Railways Act 1993. As reported in a 2003 EU working group on rail noise, British Rail was split into in excess of 130 divisions, most of which were privatised during 1994. Passenger services are run by 25 train operators under franchises granted by the Strategic Rail Authority. The train operators lease stock from rolling stock operating companies (ROSCOs) and stations and depots from Network Rail. Freight services are run by owner operators using their own locos and either their own or privately owned wagons. The train and freight operators obtain use of the tracks by means of access agreements with Network Rail.
None of the contracts between parties in the industry specifically deal with noise. The contracts between Network Rail and UK Train Operators includes an environmental clause placing responsibility for investigating and deciding action on environmental conditions. Under this clause Network Rail can decide on action to be taken by the Train Operators but have few contractual levers to force them to comply. The access charging regime does not currently have any provision for differential charging based on environmental criteria, including noise. Whole city noise maps are being produced in the UK. However, the application of noise mapping in the UK, as an effective tool in controlling rail noise, is going to be difficult to implement. As with many other EU countries, there are no limits for controlling noise levels from trains that run on existing track, nor is there a cohesive structure to implement an action plan.
An example of successful use of noise mapping, planning and execution of noise control strategy is the model being applied by Queensland Rail (QR) Australia on a State-wide basis. It should be noted that as with the experience in Europe, other Australian States have gone down the path of rail and track privatisation. This, together with the historical fact of States adopting different gauges and separate State environmental regulations on such matters as railway noise, results in the Australian experience being analogous to that in Europe. It is a macro-example of how noise management and types of rolling stock can diverge across geographical areas. It also shows how a successful model can be developed independently where there is organisational cohesion.
Firstly, QR completed a comprehensive project to determine the noise footprint from its existing operations across the Queensland rail network. The noise footprint was prepared using SoundPLAN environmental software, which predicted average energy (LAeq) and single event maximum noise levels across the network.
The modelling predictions were verified through site measurements. At all sites measured with and without noise barriers, difference between the measured and predicted levels were within ± 2 dB(A), with most sites within ± 1 dB(A). This is considered to be very good correlation for transportation noise modelling and comparable to accuracy ranges found in other transport modes such as road.