Blast experts propose complete risk assessment of vulnerable lines after last week’s bomb attacks

Engineers specialising in the effects of bomb blasts are to meet London Underground managers to propose a series of changes to the Tube network in the wake of last week’s terrorist attacks.

The move comes after Thursday’s attacks in central London sparked security alerts on high-profile projects in the capital (pages 10-11).

Philip Esper, a director of EBI Engineering, and Bill Keane, a director of Clarkebond Engineering, have written a series of recommendations to aid London Underground’s planning for the prevention of terrorist attacks. The duo complied a similar report after the Bishopsgate bomb in central London in 1993.

Trans4M, one of the three divisions of the Atkins-led Metronet consortium, has already been in contact with Esper regarding the report. Metronet is responsible for upgrading and maintaining six of the underground lines, including the Circle line, which was targeted at Edgware Road and Aldgate.

Esper, a former Arup consultant who has trained London Underground engineers, and Keane have called for a complete risk assessment to be undertaken of vulnerable lines, tunnels and Tube stations, alongside a structural integrity assessment of older tunnels. This could involve the replacement of brick arches with concrete arches.

The paper, which has been seen by Building, calls for the swift identification of “soft targets” – such as cut-and-fill tunnels that are at shallow depths – in order to determine the most vulnerable points of the line.

It also calls for the use of computer modelling to assess the response of tunnels to different detonation devices. This information would be used to predict the risk levels for various attack scenarios.

If the network remains a soft target it will continue to be a target

Philip Esper and Bill Keane

Other recommendations in the paper include:

  • Having drivers at both ends of trains to assist with evacuation
  • Installing black boxes to enable real-time monitoring of the network
  • Installing bomb detection facilities, such as X-ray or vapour detection devices, at ticket barriers.

Esper and Keane say in the paper “that a measured response is required to recent events but it should also be borne in mind that if the network remains a soft target it will continue to be a target”.

The paper adds: “The technology does exist, but at a cost. This cost may be a small price to pay for gaining the confidence of the public to continue to use the public transport system.”

John Haddon, an Arup director and security expert, said that lessons could be learned from the security measures already used in the construction of modern buildings. He cited the use of low hazard materials to limit injuries inflicted by flying glass, which is now accepted good practice. He said: “Perhaps there is a need for research into the use of similar materials on Tubes and buses.”

Haddon added that Arup is preparing its own paper involving specialists from across the company including blast, fire and evacuation, security and terrorist experts. He said: “Our areas of focus will be evacuation and communications, changes in the use of materials for public transport vehicles, along with the continuing hardening of buildings against the threat of biological and chemical attack.”