The challenge of noise abatement
Reducing noise emissions is among the most pressing tasks in rail transportation and rail traffic noise from highly frequented track sections presents a particular burden for residents. In its capacity as one of the leading wagon hire and rail logistics companies in Europe, VTG is fully aware of and accepts its responsibilities in this matter.
We consistently invest in innovative technologies for new and existing wagons, in order to continually make freight traffic quieter. It is our declared aim to improve the quality of life of the people affected by noise and to sustainably ensure the future of rail, which is the most environmentally-friendly form of transportation.
“Sound” is only perceived as “noise” to the human ear once it becomes exceptionally loud, long-lasting and unpleasant. Yet noise has no measurable size and it is only accessible indirectly through the intensity or volume of a noise. In order to determine sound volume, sound pressure and frequency are measured and expressed in a conversion scale in decibels.
It is interesting that in terms of human perception, a 10 decibel increase in volume corresponds to 50 percent more noise, regardless of how many decibels the initial noise is. The same also applies in reverse: reducing the volume by 10 decibels represents a 50 percent decrease in noise to the human auditory system.
Measures against traffic noise
Reducing noise directly at its source
Rail transport is setting new standards in safety and environmental protection. Although it is still as popular as ever today, persistent rail noise is a threat to this broad-scale acceptance. Noise-reduction measures, such as equipping wagons with low-noise brake systems, are set to provide relief for this situation in the future.
The volume of freight traffic in Europe is steadily increasing and, as a result, so are noise pollution levels. One part of the national transport budget is already allocated to noise abatement measures, especially for the construction of sound barriers. As a consequence, innovative technologies are becoming more common in an attempt to contain noise from its main source: the contact between the wheel and the rails.
Tried-and-tested solutions for quieter rail traffic...
- Noise barriers (low/high)
- Track grinding
- Rail dampers
- Rail greasing equipment
- Anti-drumming for bridges
- Fitting whisper brakes (LL and K-brake blocks, disc brakes)
Whisper brakes: effective noise reducers
Brake blocks are traditionally made of gray cast iron which is a coarse iron-graphite mixture. These particular blocks have been used as the starting point for the current noise-reduction measures. In addition to tests which are still being carried out, such as a noise-reduction coating for the wheelset axle and sound absorbers on the wheelset disc, changing to composite brake blocks also pledges sustained improvement.
These so-called ‘whisper brakes’ are made of new material mixtures, i.e. mineral fibers, rubber and resins. Without impacting the braking process itself, the composite brake blocks effectively prevent the wheels from scraping. Retrofitting with whisper brakes can reduce noise by up to 10 decibels, which corresponds to a 50 percent decrease (see info box below). However, in order for the human ear to appreciate this difference, at least 80 percent of all wagons per train have to be converted.
K- and LL-brake blocks
There are currently two different options available for equipping wagons with quieter brake blocks. K-brake blocks (composite material brake blocks) are primarily fitted for newbuild wagons and existing wagons can be fitted with LL-brake blocks (low-noise, low-friction brake blocks), which were approved for use throughout Europe in 2013. However, a higher degree of wheelset disc wear and tear leads to significantly higher operating costs, regardless of which brake block type is fitted.
Noise abatement funding
Noise abatement at VTG
Around five percent of all Germans are affected by rail noise and solutions for freight traffic are particularly sought-after. In order to relieve the burden for people, VTG is continually extending its dedication to noise abatement on the rails. In particular, a worthwhile contribution to reducing noise emissions has been made through the efforts to modernize the company’s wagon fleet.
The use of noise abatement technologies on wagons significantly reduces rail noise and this is exactly why VTG has already been equipping its newbuild wagons with k-brake blocks since 2005. The brake blocks, made of special composite materials, prevent the wheel from roughening during braking. Smooth wheel and track surfaces ensure long-lasting and quieter rolling noise. By August 2014, 20 percent of the European fleet in operation was already fitted with K-brake blocks which are the quieter alternative. VTG’s objective is to fit a further few thousand wagons with k-brake blocks by 2020.
Noise insulation for the existing fleet
Furthermore, VTG is working on a concept to significantly reduce noise emissions for its existing fleet. The company has started a pilot project with one of its customers, Evonik, in order to convert the existing wagons to LL-brake blocks (low noise, low friction) which also prevents wheel scraping. The advantage is that the innovative LL-brake blocks can generally replace the classic gray cast iron blocks, without requiring any additional modifications to the brakes. However, higher operating costs are the consequence regardless of whether K or LL brake blocks are used.
Innovations for quiet freight traffic
VTG has been intentionally researching technologies to achieve greater noise absorption for years. For instance, applying a coating to the wheel shaft and wheel disc is currently being tested to absorb noise. VTG is also trialing special wheelset disc sound suppressors for acoustic decoupling directly on the bogie-running gear as well as using disc brakes.
VTG’s constantly new technical approaches enable the company to be actively involved in reducing noise pollution and helps to make freight traffic quieter, more environmentally friendly and even more sustainable.
Effective noise control needs incentives
Switching to noise abatement technologies involves a significant investment for wagon keepers. Various noise protection support programs offer incentives to convert existing wagons to composite brake blocks at an early stage. Nevertheless, many companies feel that more needs to be done.
According to the declared policy objective, rail traffic noise in Germany is to be considerably and sustainably reduced by 2020. Two support programs are in place to contribute to the necessary measures being promptly implemented. They make it easier for wagon keepers to convert their wagons to quieter composite brake blocks and support the use of freight wagons equipped with noise abatement technologies.
Noise differentiated track charges
The German Federal Ministry of Transport and Digital Infrastructure (BMVI) offers one-time support of up to 844 euros for the conversion of each wagon, regardless of whether the wagon keepers convert to K or LL brake blocks. In addition to this support, DB Netz AG has introduced a noise-related infrastructure charging system (LaTPS) for railway undertakings (RU). "Silent" freight trains are soon to receive a bonus amounting to 0.05 euro based on the kilometric performance run by their axles (maximum 211 euros per axle). This bonus therefore benefits the RUs carrying out transportation.
Wagon keepers recognize the need for change
Many wagon keepers feel that despite support from the Federal Government and DB Netz AG, the financial burden for wagon keepers is still too high. The Association of Freight Wagon Keepers in Germany (VPI), among others, considers various factors of the existing support program to be problematic. For instance, wagon keepers have to provide evidence of the annual kilometric performance of the wagons, via confirmation from the railway undertaking, in order to receive a reimbursement of the cost of retrofitting existing wagons. However, it is not yet clear whether railway undertakings are prepared to issue such confirmation nor if and how the RUs will forward the aforementioned route bonus to wagon keepers.
VTG is also pressing for simplified and more effective retrofitting support in order to not jeopardize the competitiveness of this environmentally-friendly mode of transport. (see interview)