Then, three meters away, a train packed full of commuters goes swooshing by – giving passengers a full view of you and your room.
That was the reality for dozens of hotel and apartment dwellers in Kuala Lumpur, Malaysia. With more than seven million people living in the urban area, elevated trains are an increasingly convenient way to avoid the congested traffic on the ground. But not so convenient for the people living at train elevation.
To combat the problem, Malaysia tested a brand-new solution – enclosing the tightest section of track with a “tunnel in the air.” And they were able to do it without any interruption to commuters.
The tunnel in the air is made up of 363 cushions made of a high-performance fluoroplastic film. The cushions were built in steel frames and inflated. Each has a unique three-dimensional shape which required special software to construct. Builders completed most of the construction off-site and then easily connected it around the track. It provides privacy for residents and commuters, and also reduces noise from the train.
Architen Landrell, a design and manufacturing company in the UK, implemented the complex lightweight solution. While it was a novel solution for the elevated train, it was a favorite solution for the firm. They had already installed more than 6,000 structures in 48 countries.
The film used in the lightweight cushions is made from ethylene-tetrafluoroethylene (ETFE) from 3M. It’s a plastic material that can be extruded – melted and formed into a thin film – into varying levels of thickness and colors. It’s ideal for roof construction, because it has only about five percent of the weight of a comparable glass construction and still lets in the sunlight. ETFE is flexible, resistant to chemicals, including vehicle emissions, and is so smooth that a rain shower is enough to clean the panels.
It has been used in the Salzburg Train Station, the ARTIC traffic hub in Anaheim, California and Minnesota’s U.S. Bank Stadium. The film is puncture-resistant and even holds up under snow and hail – a must in wintry climates like Minnesota.
Besides being a fabulous fit for lightweight construction, ETFE is also used in a range of applications – including oil and gas, electronics, and chemical processing. Since it has low flammability combined with high transparency and resistance to weathering, it’s well-suited for everything from wiring to pipes to films.
The science behind these materials makes life a bit easier whether you’re working in a food science lab, developing fuel hoses, or creating cushions of air to protect people from prying eyes.