Noise-optimised rail pads and quiet brakes for tackling an increase in rail traffic in Switzerland

© Federal Office for the Environment, Switzerland.

Context

The opening of the New Alpine Transversal (NEAT) Base Tunnel through the Gotthard and the expansion of Swiss rail infrastructure was expected to increase rail traffic and exacerbate existing problems with exposure to rail noise in Switzerland. At the same time, it was a long-term aim in Switzerland to halve noise emissions from the domestic rail network by 2020.

To address noise from freight wagons, the Railway Noise Abatement Act was developed in cooperation with stakeholders. This law complements the law of 7 October 1983 on environmental protection and acts to reduce noise emissions from railways through measures that target railway vehicles, rail infrastructure, sound propagation and existing buildings. The legislation sets out the obligation to retrofit freight wagons and provides financial support for research in the field of noise-limiting technologies.

As a result, a package of measures was implemented, including the replacement of old cast iron brake pads with newer composite brake pads which are quieter, and the development of improved rail pads to dampen the noise produced.

Measures and outcomes

Between 2000 and 2015, all Swiss freight wagons (approximately 9,500) were equipped with quieter, composite brakes. Freight wagons with cast iron brake pads produced 92dB(A) of noise pollution at a speed of 80km/h and at a distance of 7.5m. In contrast, the new composite brakes generate 81dB(A) of noise pollution, below the 83dB(A) federal limit. It is estimated that a freight car with old cast iron brakes causes the same noise emissions as 13 to 20 freight cars with modern K-block brakes. By the end of 2020, over 99% of freight traffic met the new requirements to use composite brakes or disc brakes.

This measure was insufficient to protect the entire population exposed to harmful levels of rail noise: 16,000 people are still affected by harmful or annoying rail noise during the day and 87,000 at night. This number is expected to be further reduced with additional measures, such as the development and implementation of noise-optimised rail pads. Research in the field of noise-limiting technologies is ongoing, with an investment of several million Swiss francs. Field trials with the improved rail pads have shown reductions in noise emissions in the range of 3dB to 4dB with respect to conventional hard rail pads.

It is estimated that every decibel reduction in noise emissions from the Swiss rail network reduces the number of people affected by noise by 10,000. Expected benefits include lower costs in the health sector and for rail maintenance, and increased property values.