een trein rijdt voorbij een meetopstelling bij een diffractor

Increasingly quieter train tracks (39/50)

In our densely populated country, people quickly get annoyed when a train flies past. Limiting such annoyance is crucial, especially if we want to make more intensive use of the environmentally friendly train tracks.

Until the Environment Act (Omgevingswet) can be implemented, the Netherlands has various rules for two types of railway noise. At M+P, we have in-house specialists for both types to reduce any annoyance. For example, Wout Schwanen focuses on the rolling noise of moving trains on through tracks. Edwin Nieuwenhuizen deals with the squeaking of shunting trains in the yard.

Quiet brake pads

For the rolling noise, it is important to realise that both the wheels and the tracks radiate noise, says Wout. “It's the sound of metal on metal. To limit that, both parts should be as smooth as possible. This can be done, for example, by regularly grinding the tracks as well as the wheels. A major problem, however, is that most goods trains have cast-iron block brakes. As a result, the wheels coarsen quickly and any noise increases. Fortunately, there has been a major breakthrough in recent years with the introduction of composite brake pads.”

Squeaky switches

A similar favourite at the shunting yard is the invention of so-called friction improver, Edwin explains. “If you spray it on the tracks, the friction between the wheels and the tracks changes. The spray muffles the squeaking when a train switches from one track to another. Squeaking usually causes a great level of nuisance so a lot of money has been pumped into solving this problem. M+P has contributed to several government programmes for this purpose.”

meetinstrument op een spoorstaaf

Requirements and tests

Alternative solutions have also been researched by M+P over the years. Consider, for example, track and wheel mufflers: blocks on the tracks and wheels that lessen the vibrations and thus reduce noise. Wout: “We measure exactly how the noise changes, depending on the type of vehicle, for example. For various mufflers, we have determined how much reduction they provide. We have also set up requirements and tests to determine whether the mufflers do what they promise.”

Policy determines

New breakthroughs that ensure quieter tracks require a proper policy to begin with, Edwin stresses. “For example, Europe encourages the use of quieter composite brake blocks by only allowing trains equipped with them on major corridors. Local governments can also mandate the introduction of rail and wheel dampers. Naturally, such measures do cost a lot of money, so the question is always whether it is worth it.”

Invention remains necessary

At the same time, we need to keep looking for innovations, Wout believes. “A good example are so-called diffractors: elements that deflect sound. By adding these to noise barriers, you can achieve the same as with a 1 to 2 meter screen elevation. A Dutch invention for road traffic that is now also included in the calculation models for train tracks. If we truly want to make the more sustainable transition from road to tracks, such new ideas will continue to be necessary.”