FOI request detail

Sea level rise and underground resilience

Request ID: FOI-0520-1819
Date published: 26 June 2018

You asked

If mean sea level rise turns out to be significantly greater than that predicted by current models, what is the risk that the underground could become unusable in the long term? Please provide information on the risk of the underground becoming unusable in the long term as a function of the mean sea level rise. This could be either because the tube itself is flooded, or access to the stations is prevented by water levels. A table of risk as a function of mean sea level would be ideal, e.g., at 1m, 2m, 4m, 8m, 12m. Please indicate the general sections of the system that would be disabled at each level. Example table: Rise Risk of System Loss Area of London Affected. 10m 100% Westminster, City of London 1m <5% City of London

We answered

Our Ref:         FOI-0520-1819

Thank you for your request received on 29 May 2018 asking for information about the resilience of the London Underground should sea levels rise.

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm we hold some of the information you require.

It is a legal requirement under London Underground’s Safety Certificate and Authorisation under The Railways and Other Guided Transport Systems (Safety) Regulations (ROGS) that the residual (post mitigation) safety risk from flooding must always remain “As Low as Reasonably Practical” (ALARP). Beyond the minimum ROGS requirements, London Underground has adopted a risk-based approach to further improve (reduce) its safety and business risk exposure to flooding to achieve the best results possible using the budget and resources available. The London Underground Comprehensive Review of Flood Risk (LUCRFR) project was therefore established in 2014 to review all significant sources (both natural and non-natural) of flooding risk to London Underground. This is an ongoing programme of work.

In respect to sea level rises, which London Underground categorise as tidal - the River and the lower reaches of some of the tributary rivers are affected by the tide. If low atmospheric pressure coincides with a high tide, a tidal surge may occur which can result in serious flooding. London is however protected to a high standard by the combination of the river walls and the Thames Barrier, we also work very closely with the Environment Agency who are the experts in this field, for example; the tidal hazard source was hydraulically modelled in detail by the Environment Agency in order to comply with their statutory obligations as the risk management authority for Main Rivers in England and Wales, the data was then provided to London Underground to be factored into the LUCRFR.

More information on this subject can be found online:

In accordance with the FOI Act, we are not obliged to supply you with the requested table or a copy of the LUCRFR as this is subject to statutory exemptions to the right of access to information, under Section 38(1)(b) of the Act.

Whilst we make no suggestion that you would use this information for anything other than you own personal interest, disclosure of this information to you has to be regarded as a disclosure to ‘the public at large’. This information could potentially be obtained and utilised by individuals who may wish to use this information to cause disruption or harm to the London Underground network. The London Underground system is an attractive terrorist target for several reasons including, its importance to London and the knock on effect to the nation’s economy if it is disrupted, the publicity gained from attacking an iconic transport system and the attractiveness of the system for a mass casualty attack due to its open, mass transport nature. It is also part of the nation’s critical infrastructure by virtue of its central importance to the functioning of London and its economy.

Disclosure of information could compromise the London Underground’s network and would place members of the public and TfL staff at risk by highlighting areas on the network which could be susceptible to being targeted.

The use of this exemption is subject to an assessment of the public interest in relation to the disclosure of the information concerned. We recognise the need for openness and transparency by public authorities, but in this instance the public interest in applying the exemption, in order to minimise risks to operational resilience, safe operation of the London Underground network, the welfare of staff and members of the general public, outweighs the public interest in disclosure.

If this is not the information you are looking for please feel free to contact me.

Please see the attached information sheet for details of your right to appeal.

Yours sincerely

Gemma Jacob
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London

[email protected]

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