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Blast-Resistant Trains

THE MADRID TRAIN bombings in 2004 killed 191 people. The London attacks on trains and a bus a year later had 52 victims. So it’s no surprise that the European Commission, which is the executive body of the European Union, would be looking for ways to make railcars safer in case of any future terror attacks. The commission sponsored a project called SecureMetro that has been looking into modifications to make railcars blast-resistant.

The project was led in part by the NewRail Research Centre at Newcastle University in the United Kingdom. Tecnalia, a technology company in Spain, oversaw the testing program for the materials.

The project focused on ways to mitigate the effects of a blast from within the railcar, which is the worst scenario. They are seeking ways “to absorb the energy, prevent the energy reflection, and also to stop the internal fixtures within the vehicle [from] being detached [and] thrown around the vehicle,” says Richard Seddon, project manager at Tecnalia.

The two main issues that engineers addressed were how to reduce debris and how to contain the impact of the blast. Achieving those two objectives would not only help save lives during the initial blast but would also make for clearer paths, which would make it easier for passengers to evacuate and for first responders to get through to the victims.

In terms of debris, a key concern is glass. Many explosion injuries come from glass shattering during the bombing. Conor O’Neill, who was the project coordinator at NewRail, says that adding a film to the windows could increase the likelihood that the windows would come out in one piece during an explosion, rather than shattering into thousands of dangerous shards. Even a thin film might be helpful in this situation, says O’Neill, who adds that some current trains already have graffiti-prevention films on the windows.

Another danger in an explosion is that features like speakers or ceiling panels become detached from ceilings and walls and turn into projectiles. “In a lot of vehicles now, there’re a lot more systems like TVs and sound systems and things like that.... What we saw is that they do have the potential to cause quite considerable damage,” says Seddon. To minimize that risk, the engineers devised ways to tether such items to the railcar structure using retention wire so that, even in a blast, the items would stay attached and not fall onto the passengers or into the aisles.

Researchers also examined the possibility of using energy-absorbing materials, such as metallic foam. In addition, they looked at how railcars were designed to figure out whether a certain amount of built-in flexibility at joints would prevent components from breaking apart in a blast.

The SecureMetro project tested various technologies in real blasts in decommissioned metro cars as well as in demonstration vehicles. First, a normal railcar was tested to see how the current materials held up in a blast, and then new materials and designs were tested. This allowed the engineers to devise various specifications for the new technologies.

One of the goals of the project was to develop options that could be built into future railcars or retrofitted as modifications on current railcars. So not only did they have to be cost-effective, but they also had to meet standards “relating to rolling stock on our current rail tracks,” according to O’Neill.

As researchers did their work, they also kept in mind the need for anything they developed to be easy for industry to adopt. “Where possible, we selected materials that were already accepted by the rail industry but used in other applications or in other areas of the vehicle,” says Seddon. And they were mindful of existing requirements, such as fire codes. “So our hope is that they can more easily accept our findings,” he says. However, he acknowledges that this work does involve a change in the industry, which is always a challenge.

The SecureMetro project went on for more than three years and was completed earlier this year. The group will be presenting the findings to the European Commission, says O’Neill, and they’ll “discuss with them what the impact of our findings has been, what the impact on the manufacturers, the rolling staff operations, and the passenger might be. And from that, then, hopefully try and develop some form of industry guidelines or design specification.”

This work isn’t unique to Europe; similar projects are happening elsewhere, such as at Northwestern University, in Chicago, where Greg Olson, Walter P. Murphy Professor of Materials Science and Engineering, has led students for several years in a search for materials and designs that would absorb bomb energy and strengthen railcars. The project at Northwestern uses computer simulations at first and then tests materials in a water chamber in a ballistics testing laboratory.

The students at Northwestern have looked at materials that could help protect passenger train cars as well as cars that carry hazardous materials such as chlorine. What they are designing is very high-strength steel “that can still stretch a lot to absorb a lot of energy,” says Olson. That project is under the heading of Cyber Alloys 2020, with a target to get materials in use by 2020.