Rolling stock & Rail Vehicle Design, Safety, Standards & Regulation

Protecting passengers and drivers: Impact testing glass in rollingstock

Ballistic & Mechanical Testing is working with train manufacturers and owners to ensure windows are properly impact-tested, and keep their strength throughout the life of the rollingstock.

Primarily, Ballistic & Mechanical Testing (BMT) is a laboratory that specialises in testing armour, primarily in military and law enforcement. But much of that testing pertains to transparent armour (i.e. glass) – and that’s where BMT is in a position to serve the rail sector.

“A lot of the glass that’s used in the rail industry is impact tested,” BMT General Manager Ben Eu explains to Rail Express. “That testing is for the laminate strength, and the impact resistance of glazing.”

Eu says there are several standards typically used in Australia for glass testing in public transport: the British Rail Board (BRB) 566 for high impact resistant windows, the US standard
issued by the Federal Rail Administration, and the Australian Standards for safety glazing on land vehicles, including AS2080 and AS7520.

“We work in two parts of the supply chain,” Eu explains.

First, BMT tests glass during the rollingstock delivery phase. “In some cases, for a glass manufacturer we’ll assist in their R&D phase, when they’re developing the product,” Eu says. “We also assist those manufacturers with the final stage, the certification process, before the glass is sold on.

“Often we’ll also find the train manufacturer may do some additional testing, and the end customer may want to do some additional testing as well.”

The second area of the rollingstock lifecycle BMT gets involved in is as the vehicle ages. “[Rollingstock owners] are looking at the through-life performance of the glass, as it’s
aging,” Eu says. “Typically [in a train window] you’ve got three different components: the glass, the inter-layer, and the internal film … and you’ve got different coefficients of thermal expansion through all these layers.

“So there is the opportunity, with heating and cooling thanks to environmental exposure, to see some delamination within the product, and that can lead to a reduction in performance.”

While delamination can often be observed through visual inspection, Eu says you can’t know the true performance of the glass without proper testing.

“A warranty period is nominated by the manufacturer of that glass. Once it starts to approach the end of that period, you would then take some samples and test them, to make sure they’re still offering the required impact protection,” he says.

“You’d then repeat that testing every twelve months, so you can monitor the performance of the glazing, to see if there is any reduction.

“Provided you are conducting a program like that, there is no reason you couldn’t expect glazing to last the full life of the train itself.”

BMT tests glass not only for its ability to prevent projectiles from entering the train cabin, but also to make sure external impacts don’t project small shards of glass from the window,
into the cabin.

“Small shards of glass can release from the inside surface of the glass, and could penetrate the skin or, more significantly, they could cause a very serious eye injury for a passenger,” Eu explains.

BMT is National Association of Testing Authorities Australia (NATA) accredited. Its laboratory, in Port Melbourne, Victoria, services clients in Australia, New Zealand, the UK, Malaysia, Singapore, Israel, Thailand and China.


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