BRENS GROUP - Original Rail Sound Absorbers

Original BRENS EUROPE Rail Sound Absorbers

Rail sound absorbers are a new original technology combining three essential requirements facing today´s railways: noise and vibration reduction, thermal island elimination and the use of railway surfaces for precipitation retention, and turning wastes into raw material, based on circular economy principles. Therefore, the main benefits of their use are noise elimination from rail transport, new green space creation in towns and improvement of climatic conditions in enclosed city agglomerations. “This requires modernising the preparation and realisation of railway construction that will eliminate their part played in city overheating and thermal island creation,” says Jan Eisenreich, Statutory Director of BRENS EUROPE in Plzeň.

Urban transport structures (streets, railways. tramways, parking areas, storage and manufacturing surfaces) strongly influence the city climate and the quality of life in towns and cities. They are a source of noise, vibrations and dust. Streets, parking areas, storage surfaces, and manufacturing sites create huge “heat accumulators”. Urban development thus creates heat islands, which are a significant factor of microclimatic changes. Rapid and safe road transport requires the construction of solid, level and drained roadways. Their use for the humanisation of urban spaces is minimal. Railway or tramway transport requires a permanently stable track ge

ometry. Today, this is ensured by technically well mastered track understructures and superstructures made of crossbeams laid on a gravel bed or a fixed track. Consequently, the whole space between the rails and within them is ready for being returned into the life cycle of the Earth by nature-friendly measures. The current method of creating green tramway tracks is to spread earth and humus layers within the track structure, overgrown with intensively or extensively cultivated strips of grass. “From the environmental point of view, without sufficient artificial watering in the summer months, however, natural lawns lose their purpose, the noise

In the Converting Waste into Resources competition, the BRENS STERED rail noise absorber with a water retention function has been accorded the “Best Secondary Raw Material Product 2018” by the Minister of Industry and Trade of the Czech Republic. This new and advanced technical solution is certain to find its use in other European cities in their effort to cope with environmental problems, the humanisation of public space and adjustment to climate change. As a matter of interest, in 2018 the Slovak city of Košice became the

first city in the world to use the BRENS STERED rail sound absorber with a water retention function in the modernisation of the tram track in SNP Street with a surface formed by an artificial lawn and vegetation carpets. Sixty per cent of the original concrete panel surface was replaced by water retention and sound reduction absorbers, thus reducing sunshine heat accumulation on a 1 360 m long track by 55 per cent to 482 000 litres of rainwater. This installed rainwater retention capacity will retain up to 97 per cent of the annual rainfall total.

dampening is reduced, dust increases and, in addition, the withered grass may emit further allergens into the air,” adds Director Eisenreich. That is why BRENS EUROPE sought and has found a solution.

n THE BRENS STERED RAIL NOISE ABSORBER The rail noise absorber with a water retention function is made from wastes generated by the automotive industry, specifically from recycled synthetic textiles and rubber, where some 16.5 tonnes of processed synthetic and 27.5 tonnes of recycled rubber are needed for 100 metres of a two-rail track. This material is obtained exclusively from reprocessed wastes in the automotive industry (e.g. materials used in the manufacture of car seats, carpets, filters, etc., which, using the STERED patent-protected technology, acquire new utility properties). Another material base is reprocessed rubber waste from tyres and other technical rubber products. These input materials are pressed into absorber parts arranged sandwich-wise. For a stonecrop sedum vegetation surface, a minimum amount of earth substrates made into a cultivation fabric is needed. “The BRENS STERED patent-protected rail noise absorber with a water retention function is to date the only known technical solution based exclusively on the circular economy principles, using only synthetic textiles and rubber grit. After the expiry of the absorber service life, i.e. after about 20 to 25 years, the material bases will be separated by special technology and will be prepared for new pressing,” Eisenreich explains. During the recycling process, all mechanical impurities and the dust absorbed by the parts during their exposure in the rail will be removed. The proper service life of the synthetic textiles and technical rubber is more than 50 years, after which time the material can be once again recycled and the waste generated by repeated recycling can be further used in industry as a valuable fuel.

n ADJUSTMENT TO THE EUROPEAN CLIMATE The current climate change and the requirements concerning the environment in towns and large industrial agglom

erations call for a reappraisal of the currently used conventional green rail track technologies with the use of natural grass strips and earth. The growing surface areas of tracks built in this way obviously raise the requirement for hygienically safe water sources for watering, and call for the coverage of the financial costs incurred by the maintenance of the surfaces and the vegetation cover. Moreover, the current moisture deficit of rainwater experienced by all of Europe requires additional watering. Longer spells of dry weather and hot days lead to the complete drying out of the cultivation layer within a short time. The layer is relatively thin, given by the construction of the rail, being not more than 16-18 cm thick. The subsequent dehydration of the grass cover results in its

BRENS EUROPE The firm also concerns itself with railway crossings and low-noise barriers, in addition to rail noise absorber manufacture. Low BRENS BARRIERS for conventional railways make it possible to use an application in the rail with a rail grill, without grounding in the soil, enabling a prompt evacuation of persons from a train and urgent intervention by rescue teams in emergency situations. Low noise barriers for tramways are formed by gabion baskets filled with recycled materials retaining water. The outside

complete extinction, while the overheated and dried earth between the rails also loses its water retention capacity, and in heavy or torrential rain is washed away or eroded. “Both experimental measuring and operating conditions have shown that, on a rockcrop SEDUM or artificial lawn vegetation cover, the rail noise absorber with water retention will always retain torrential rain and slow down the flow of water into the sewerage system with a delay, until the absorber has been saturated,” Eisenreich explains.

n NOISE, VIBRATION, AND SURFACE TEMPERATURE REDUCTION AND HEAT ACCUMULATION The actual material base of the STERED recycled synthetic material shows a very high sound absorption capacity. The sound and vibration reduction measuring in absorbers built in the rail has proved a 9-dB noise emission reduction under operation. Concrete panels or the paving of the track rails are heat collectors strongly accumulating sunshine heat. For example, one metre of a double track will accumulate some 2 500 kJ of heat. On the other hand, one metre of a double track with BRENS STERED absorbers accumulates only about 173 kJ, and a natural lawn track with soil 210 kJ. This proves that, in the case of BRENS STERED noise absorbers, heat accumulation is about 15 times lower, strongly reducing the ambient air temperature. The change of the concrete or asphalt surface into vegetation surface absorbers is to be felt especially during the night.

of the barrier is designed so as to allow it to be overgrown with a natural vegetation cover. In newly built tunnels and on long elevated roads, rescue sections from prefabricated BRENS ACCESS segments are installed. These surfaces, which are not accessible to the public, serve for rescue purposes to allow access to the rail engineering structures and the emergency escape of persons from the track. The latest BRENS ACCESS rescue surface application was installed at both portals of the new Ejpovice Tunnel in Plzeň at the end of last year.