Wednesday, 17 December 2014
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Improved carriage design could reduce bomb-related injuries

Engineers at Newcastle University are hoping to reduce the risk of injury from terrorist attacks on trains by improving carriage design.

The researchers have developed a series of measures that can be retrofitted to train or metro carriages in order to reduce injuries caused by bomb explosions, particularly those related to shrapnel.

The work was carried out as part of a three-year EU-funded project called SecureMetro, led by Newcastle’s NewRail research centre, as the precursor to developing new standards for carriage design that could be easily implemented.

‘The European Commission raised a security call based on the terrorist attacks in Madrid and London and it was felt more research was needed in this area,’ project leader Conor O’Neill told The Engineer.

‘We had a look at how vehicles can respond and what can be done from a design perspective to [reduce] the number of injuries and fatalities.’

One of the key improvements was the development of a tethering system to prevent heavy items such as speakers, emergency handles and even ceiling panels from flying around the carriage should their joints become detached in a blast.

Source: Newcastle University

The researchers carried out full-scale controlled explosions on two test carriages and their prototype SecureMetro vehicle

As well as preventing them from hitting people or creating shrapnel, this should also prevent them from becoming debris and blocking a passenger’s escape route or preventing rescuers from entering the carriage.

‘We’ve been looking at a number of things [to create tethers] but even a simple method such as a thin wire cord is very effective, or even just building in a bit of flexibility around the joint areas allow the panels to move but they’re not so rigid that they end up being pulled out,’ said O’Neill.

Other changes include the use of anti-graffiti film on the windows to prevent them from shattering and lighter-weight and more energy-absorbent materials to reduce the impact of a blast.

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Source: Newcastle University

The researchers found that tethering the ceiling panels prevented them from falling into the carriage

The researchers carried out a full-scale test explosion in order to assess how the blast impact travelled through the vehicle and its effects on the structure and interior, filming and playing the explosion back in slow motion to analyse its progress.

Other members of the research consortium in Spain conducted tests of individual components to assess a blast’s impact on different materials, joints and subassemblies.

The Newcastle team then used the results to build (and then destroy) a full-scale prototype carriage featuring the new adaptations, the results of which will now be used to make design recommendations to European standards bodies.

‘These aren’t big, heavy solutions and they’re not costly solutions either,’ said O’Neill. ‘We were very much of the mindset that these had to be retrofit solutions but they also had to be cost effective in order to ensure that later down the line they get implemented in vehicle design.’


Readers' comments (3)

  • Not sure about putting anti-graffiti film on the window. Surely that would further contain the blast within the carriage, resulting in more injury, although maybe safer for anyone outside - as it's a train no one in range outside.

    Not sure about tethering - might help, but most important techniques are shrapnel reduction and dissipation of the pressure/heat wave, unfortunately on a crowded train, that will be the people.

    The best way to protect is to stop the blast in the first place, monitoring, intelligence and perhaps less crowded trains (seats for everyone) and the political will to resolve the causes of terrorism in the first place.

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  • Getting the 'right' stiffness in structure and finishes is a great idea all round as the more flexible the structure can be and still work well the lower the peak loads and the less-likey that items will break away and become additional shrapnel. However, enough stiffness is required to ensure that the items perform their functions well enough for long enough.

    It is also important that stiffer items not be directly attached to, or connected by, very flexible items as this can result in local stress risers as waves of energy pass through and along paths, resulting in unexpected separations. It is keeping things in the correct range of stiffness that makes for a successful system.

    I watched many a vibration and shock test in the late 60's and learned that lesson early on. A rocket launch is like an explosion in many ways.

    One analysis trick is to calculate the natural frequency of every item, with the right connections stiffness and make sure that there are no harmonic matches in nearby components - that too can result in some exciting behaviour but there is such a thing as too much excitement when you are carrying people.

    Some of the modern analysis programs could easily be tweaked to perform such checks and lead to better performance all round. Systems that do not sing in harmony will be easier to keep pleasantly quiet.

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  • It seems from the European Commission present bid that public transport bombing is taken as a very probable event and therefore a task force has been mobilised to design measures to cope with the probability and a lot of money will be spent on each and every carriage in Europe. What can we comment on this?

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