Wed Sep 17th, 2008 at 07:05:50 AM EST
This year, it was all good news for the Chunnel: tunnel and shuttle services operator Eurotunnel at last managed the financial turnaround, and high-speed services operator Eurostar achieved ever higher records in passenger numbers after service improvements (also see European HSR expansion in 2007).
And then, out of the blue, disaster struck: last Thursday (11 September), there was a fire on a truck transport shuttle (see Salon discussion). Everyone was brought to safety, but the massive structural damage to the tunnel from the 16-hour, >1000°C fire means reduced services across only one tube, possibly for months. (An inconvenience also affecting the upcoming ET Paris Meetup.)
A rescue car evacuating the truck drivers just left the service tunnel; the only sign of the fire five kilometres behind the portal. Photo by Denis Charlet AFP from La Provence.com
Out of the blue? Well, not really. Follow me below the fold for a short explanation of Eurotunnel's Achilles Heel, and some I-told-you-so's.
Eurotunnel, with its two separate tubes for trains and one extra service tunnel, and all kinds of warning devices, is very safe from a life protection point of view.
Emergency personnel rides the special vehicles inside the service tunnel. Photo from The Internet Land-Rover Club
However, material loss is another thing. The crux of it, as I commented upon the first news of the fire:
would closed cars limit the spread (and airfeed) of fire, trains could get out of the tunnel to the firefighters rather than the other way around*, and no closures and eventual expensive tunnel wall reparations would follow.
A fire is a great danger in tunnels of any length. What's special with long tunnels is that passage time is long – thus an eventual fire has more time to develop.
When lots of long tunnels began to appear on high-speed lines (in Japan and Germany), safety experts thought presciently that if there is an emergency not affecting the train's running on the rails (no derailment), above all an on-board fire, it is faster (and safer) to get the train to the emergency team outside the tunnel, than to get the emergency team into the tunnel. What's more, such emergencies may cause less damage in the open.
In line with this philosophy, areas near the entrances of major tunnels were shaped for easy evacuation and easy access for fire-fighters, and fire-catching vegetation or buildings were removed. Meanwhile, trains were fitted with the so-called emergency brake override: a device allowing locomotive drivers to interrupt an emergency braking on their own judgement, and stop only after leaving a tunnel (or bridge).
Now, if the emergency is a fire, the above concept works only provided that the fire will remain localised on the train while travelling. It should be, if the train is a passenger train (like the Eurostar high-speed trains), or consists of closed cars – like, for example, Eurotunnel's passenger car shuttles:
Above: end of a Eurotunnel passenger shuttle arriving in the UK terminal at Folkestone on 22 November 2004, with the double-deck section ahead of the trailing loco. Photo by Ianm42 / LucaZone from RailFanEurope.net.
Below: inside the upper deck of a closed double-deck car on a Eurotunnel passenger shuttle. Photo by Christian Larsen from RailFanEurope.net
However, you can't drive out of a tunnel with a burning train if the train's travel wind can enter the cars and boost the fire, or when it can spread the fire along the entire cargo through open car joints. And Eurotunnel's Heavy Goods Vehicle (HGV) shuttles are open to the sides and between cars:
First-generation HGV shuttle arrives at Folkestone Terminal. Photo by Ianm42 / LucaZone from RailFanEurope.net
The reason for this was, basically, cost savings. To be able to carry the heaviest lorries, when the weight per train axle is limited, demands cars as light as possible – and fire- and pressure-proof side walls, not to mention retractable inter-car walls, mean not just extra material costs but extra weight. But this way, in case of a fire, the train must stop in the tunnel.
Already when the HGV shuttle car order was announced in the early nineties, I thought it's insane, and wondered if any cost savings would balance the eventual costs of an accident. And indeed on 18 November 1996, the first serious fire caused massive damage to the tunnel's walls, demanding a 6-month complete closure for repairs.
Above: heavy damage after the 1996 fire: tunnel walls from which enough concrete cracked off to expose the reinforcements(right); and the side of an open HGV shuttle car, which became so plastic in the heat that it buckled inwards at 3/4 height (left).
Below: inside a burnt-out open freight shuttle car, with the roof bent down.
Photos from The Internet Land-Rover Club
After that fire, it wasn't just me who had a bad feeling about Eurotunnel's safety back-up programme: it included new fire detectors in the tunnels and one the cars, emergency train routing plans, emergency practices and such, but the freight shuttles weren't to be closed. In fact, when the company bought new cars in response to growing traffic, they saved even more weight on the cars' sides:
Second-generation HGV shuttle arrives at Folkestone Terminal. Photo by Ianm42 / LucaZone from RailFanEurope.net
Eurotunnel was lucky in the next few accidents, for example a fire on another HGV shuttle on 21 August 2006 was brought under control in under three hours (see accident report [pdf!]), with damage limited to one car and the tunnel above it. But the luck ran out this time.
I wonder if they wisen up now, and dare the extra costs of replacement cars/major reconstruction of the existing cars. (But I don't count on it.)
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