Are attacks deadlier on ‘walk-through’ trains?

YESTERDAY’S terror attack raised safety concerns about the new generation of ‘walk-through’ London Underground trains.

Passengers said the explosion from the improvised device sent a ‘wall of fire’ through carriages on the packed train at Parsons Green station.

The carriages have no interconnecting doors, meaning passengers can walk through the whole train. The design allowed the fire to spread through the carriages.

The District Line S-Stock train affected yesterday has a capacity of nearly 1,000 people.

The trains were introduced in 2010 to provide more capacity.

Will Geddes, chief executive of security consultants ICP, said there were ‘ pros and cons’ with walkthrough trains.

‘If there is an explosion it is more easily contained within a singular carriage,’ he said.

‘The blast could spread out further causing a larger number of fatalities and casualties. But in other cases, for example if there is a lunatic with a machete, walkthrough carriages make it easier to escape. They also make it easier for first aiders and police to respond to an incident.’

Mr Geddes said there was no ‘clear cut’ answer, because in some cases the blast from a bomb could be more lethal if concentrated in a single carriage.

The S-Stock trains fully replaced the old tube trains on the District Line earlier this year. The old trains had separate carriages and were built in the 1970s and 80s. The S7 version can hold up to 951 passengers, with 256 seats and space for 695 standing.

The older D- Stock trains had more seats but space for only 800 passengers.

The S7 model has been gradually introduced since 2010 on the District, Circle, and Hammersmith & City Lines.

The longer S8 version, which consists of eight carriages rather than seven, runs on the Metropolitan Line. Transport for London paid Canadian firm Bombardier around £1.5billion to build 192 trains at its plant in Derby, which employs 2,000 staff.

As well as being able to carry more passengers, bosses at TfL wanted the trains to feel safer.

The walk-through trains mean women travelling alone at night can more easily switch carriages.

The newer trains have CCTV throughout and are designed to make it easier for passengers to escape any danger. They are bigger and brighter than the old trains, with bigger windows, air conditioning and designated spaces for wheelchairs.

In the UK, walk-through trains also operate on the London Overground. Walk-through trains are increasingly common on metro services around the world, including in Paris, New York, Toronto and Tokyo. The Department for Transport, TfL and Bombardier declined to comment.