The EU supports railways, because they are the most sustainable means of transportation. This, however, requires the railways to reduce noise, their most important environmental issue. Noise concern in the EU has led to the Environmental Noise Directive (END), which requires noise maps and actions plans for major railways as well as inside agglomerations. Railway noise emissions of new and upgraded vehicles have recently been limited by EU legislation.

Basically rolling noise in railways is created by rough wheels and tracks. If both can be kept smooth, noise can be reduced significantly. Smooth wheels can be achieved by replacing cast-iron brake-blocks with composite brake blocks.

Currently two types of composite brake blocks are being discussed: K and LL blocks. K blocks probably have a higher noise reduction than LL blocks, but require adapting the braking system while wagons can be retrofitted with LL blocks without adapting 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 will be cost neutral in certain circumstances. With K-blocks costs for adapting the braking system must be added.

Due to the harsh competitive transport market, retrofitting is not possible without outside financial support for railway operators. Currently EU funding is only likely for pilot or demonstrator projects; investigations into additional sources of funding are therefore needed.