Lightweight Solution as Noise Barrier and Privacy Shield
Tunnel in the Air Made of ETFE Film Cushions
Every few minutes the driverless Kelana Jaya Light Rail Train (LRT) elevated railway squeezes its way through the sea of houses in the conurbation of Kuala Lumpur, the capital city of Malaysia. At the narrowest point of the most recent development stage, the distances between the track and the nearest house and hotel are less than three meters. That leads not only to enormous noise stress for the residents. The train passengers also had a direct view into the homes and hotel rooms. Therefore, "Prasarana Rail and Infrastructure Projects", who operates the line, decided to equip the narrow point with noise protection elements and to erect a "tunnel in the air" as a privacy shield.
Architen Landrell of Chepstow in the UK, one of the leading companies for the use of membranes and films in architecture, was responsible for the implementation. The company has already installed more than 6000 lightweight constructions in 48 countries. The challenge in Malaysia was the curved route of the track and the tight space between the buildings. The company constructed the air tunnel from 363 steel frames, each one holding a pneumatically inflated cushion made of ETFE film. The tunnel has a complex three-dimensional form. None of the 363 film cushions are identical. The company developed special software to master this complexity.
The films for the roughly 2500 m2 of cushion surface were extruded by Nowofol Kunststoffprodukte GmbH & Co. KG, Siegsdorf, Germany, from the high-performance material 3M Dyneon ETFE. Transparent and silver-colored Nowoflon ET 6235Z films were installed in the air tunnel. Moreover, several empty frames allow for pressure compensation when trains pass through.
High Fire Safety and Largely Self-Cleaning
3M Dyneon ETFE is virtually universally resistant to chemicals, including aggressive exhaust gas emissions, and is regarded as non-flammable. The high-performance material conforms to the necessary European and US standards for installation in sports stadia. Architen Landrell produced further proofs of fire safety for the Malaysian authorities – an important property in the direct vicinity of residential buildings.
The construction of the tunnel took place in summer 2016 without interruption of the railway operations. The individual frames were connected to the existing elevated track construction. That was only possible with a very lightweight structure. The films weigh less than five percent in comparison to a glass construction. Thus, the support structure can be made lighter and slenderer and cost can be saved due to less use of materials.
ETFE film cushions have been proving themselves for over thirty years in every climate zone in the world. Their surface is so smooth that a rain shower is sufficient to clean them for the most part. That reduces the operational costs. For the film extrusion from 3M Dyneon ETFE Nowofol Kunststoffprodukte does not need any plasticizer or additives that could migrate and result in cracks or embrittlement nor does it provide breeding ground for algae and mold even after decades of use in hot and humid climate zones.
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