Noise Reduction in Rail Freight
This report summarizes the state of the art in railway noise control. The report is based on a series of European Union (EU) and International Union of Railways (UIC) workshops held in Brussels, Paris, Pisa and Utrecht from 2005 – 2007, on recent information from the UIC Network Noise as well as on direct contacts with the EU Commission, the railways and national ministries. The report intends to inform a wider public on the issues involved.
European Union (EU) transport policy calls for effective and efficient transport systems. Support of the railways meets these objectives in a sustainable manner. However, the impact of rail noise might result in restrictions to rail freight traffic along the most important European transport corridors.
Noise concern in the European Union has led to the Environmental Noise Directive (END), which requires noise maps and action plans for major railways as well as inside
agglomerations.The END also applies to road and airplane traffic as well as for industrial noise. Railway noise emissions of new and upgraded vehicles are limited by EU legislation. Noise reception on the other hand is subject to national legislation.
The specific situation of the railways must be considered when discussing noise abatement strategies. Important characteristics are the separation of infrastructure and operations which complicate a whole-system approach, the tight economic environment and competition in the transport market as well as the fact that railways are a long term endeavour, limiting possibilities for short term solutions.
Basically rolling noise in railways is created by rough running surfaces of wheels and tracks. If both can be kept smooth, noise can be reduced significantly. Smooth running surfaces of wheels can be achieved by replacing cast-iron brake-blocks with composite brake blocks. Other source reduction measures include rail and wheel absorbers as well as track grinding. Barriers reduce noise on the path of propagation, while insulated windows protect inhabitants directly in their buildings. Measures on the wagons have a network-wide effect, while all other measures reduce noise locally only.
Currently two types of composite brake blocks are being developed: K- and LL-blocks. Both show a noise reduction between 8 – 10 dB. K-blocks are chosen for new wagons because they have a better braking performance and are cost-neutral in comparison to cast-iron brake blocks. For retrofitting, K-blocks require adapting the braking system which causes additional costs. LL-blocks simulate cast iron block braking characteristics and can be retrofitted without changing the braking system.
Several economic studies show that railway noise reduction in retrofitting the freight wagon fleet with composite brake blocks has the highest cost-effectiveness. Also, if
composite brake blocks are combined with other measures the overall cost-effectiveness is increased.
Life cycle costs are currently being investigated. It is expected that retrofitting with LL-blocks could be nearly cost neutral in certain circumstances. Because retrofitting with K-blocks requires adapting the braking system additional costs occur.
The railway sector’s strategy focuses on equipping new freight wagons with composite brake blocks and retrofitting the existing fleet. Several incentives to promote retrofitting are under discussion. Due to the harsh competition in the transport market, the sector prefers direct subsidies in the short term and differential track access charges as a second step for achieving a silent freight fleet.