the rail engineer • November 2013
It is an international problem, so the UIC (International Union of Railways) recently held a conference on the subject at Network Rail’s Westwood facility. The conference was well attended with representatives from a number of International Rail Companies including Deustche Bahn, SNCF, OBB, Translink, Infrabel and the East Japan Railway Company. The Rail Engineer went along as well.
retained as possible. The middle ground is that the vegetation is here to stay and must be dealt with both in a cost effective way and with limited damage to the environment. Also, this vegetation can be of benefit and the conference looked at the ways that Network Rail and other companies, most noticeably the East Japan Railway, are utilising it and future options to consider.
Not just track
Many people working on the railways are merely concerned with the manmade elements of the rail, or as one of the speakers put it “that middle bit the train goes down.” However, the vegetation that borders the rail needs just as much consideration. Without management, this vegetation can become a real problem. For example, it can pose a safety risk to both passengers and staff, it can cause delays to the service by obstructing signals and lines of sight and can cause conflicts between the railways and the general public. All of these problems cost Network Rail and other rail companies time and money. The aim of this conference was to discuss how vegetation is currently managed by Network Rail and its international counterparts and to consider ideas to improve this management in regards to reduced time, cost and impact to biodiversity. Many of the old guard might like to see the rail corridor go back to how it used to be 60-odd years ago when all vegetation was removed due the risk of fire from the steam trains. Obviously, ecologists are biased the other way and want as much native vegetation
The majority of vegetation management across Europe is carried out via chemical control. The use of chemicals varies across Europe due to the legislation imposed by each individual country. SNCF (French Railways) kicked off the talks about chemical control. It is responsible for 30,000 km of rail line and, with track and rail side land, this adds up to around 100,000 hectares to look after. In order to adequately cover all this, SNCF employs 6 mainline spray trains and 25 regional trains. The use of chemical herbicides is strictly controlled by the Ministry of Agriculture and is limited for this reason. To reduce both cost and manpower, it is important that the application of these chemicals is done at the right time of year and only when and where required. As such SNCF employs a number of strategies such as the use of preventive herbicides in March to May during the germination period to limit growth, the alternation of herbicides between years and treatments to limit plant resistance and tailoring the herbicide used to the weather conditions. These measures and the development of better chemicals have allowed the SNCF to reduce the amount of herbicide they use by 3/4 since 1984.
Other railways adopt variations on this theme. In Belgium, Infrabel uses a camera and computer system in order to correctly deliver the dosage of herbicide in a bid to save costs and man power.
Mechanical methods In some areas chemical control is not a viable option and the reasons for this seem to be the same across the board - proximity to a protected wildlife site and proximity to a water resource. The traditional method of vegetation removal in these areas is mechanical; undertaken by hand strimmer, chainsaws and, if the lay of the land allows, flays. Generally sub-contractors are required, as having full time employees sitting around until they are needed is not a viable option. One sub-contractor from the USA stated that they deal with the issues involved in vegetation removal all day everyday and, as such, have a skill set generally not present in many large infrastructure companies. As mechanical removal is not a viable option for large expanses of the rail corridor, experiments are being undertaken in various countries to come up with more cost effective methods. The Japanese have been using recycled plastic sheets to cover areas of vegetation in order to restrict growth. The French have gone a step further and have been trialling the use of geotextiles placed under the ballast and/or bordering pathways. They have found that these geotextiles seem to work and are relatively inexpensive at €3 a metre. However, one major drawback is they require the removal of the ballast layer in order to be installed, so only new lines or areas scheduled for renewal are currently eligible.
The Rail Engineer Issue 109 November 2013