INTRO: Development of ballast cleaning machines with integral recycling of used ballast is helping to reduce the cost of disposal, and is becoming an important tool in the track maintenance business as legislation on waste disposal takes effect
BYLINE: Rudolf Becker and Patrick Vierlinger*
RECYCLING of used ballast merits high priority in track maintenance planning. From both an environmental and an economic perspective, sustainable ballast management is growing in importance, with integral recycling on formation rehabilitation and ballast cleaning machines offering a significant increase in efficiency.
Ever since the United Nations Conference for Environmental Protection in Rio de Janeiro in 1992, the phrase ’sustainable development’ has been a buzzword in social discussions about the future. The term was used by the Brundtland Commission in 1987 and is defined as ’a development that meets the needs of the present without compromising the ability of future generations to meet their own needs’.
With reference to the environment, sustainability in the case of track ballast is significant both in terms of ground protection, water purity and in preserving natural resources. From an economic perspective, ballast is used in huge quantities, and this alone warrants serious consideration.
In recent years much legislation has been passed on environmental protection. In Austria there is a firm commitment to comprehensive environmental protection which includes ’measures to keep the soil clean’. Other laws cover waste management and refuse dumping. The objective is to conserve raw material and energy reserves and to minimise the volume of dumped waste. Similar goals are enshrined in Swiss and German law, and there is also a European Union strategy for waste management.
Regarding the specific problem of used ballast, special guidelines and ordinances have been drawn up to reflect various provincial or cantonal regulations. In Germany DB Netz has its own internal guidelines on environmental protection, recycling and disposal of used ballast. In Switzerland the Track Excavation Guideline includes provision for evaluation and disposal of excavated track material; published in September 2002 by the Federal Office for Transport and the Federal Office for Environment, Forests & Land Conservation, it came into effect three months later.
Generally, a distinction is made between uncontaminated, or slightly fouled, and contaminated ballast. The contamination consists of various materials and pollutants.
The material contamination such as fine particles from attrition and splintering of the ballast, spillage and rising subgrade material can for the most part be removed by screening during operation of a ballast cleaner. But some pollutants require special treatment and possibly specialist disposal. Examples are: