TfL Ref: 2214-1819

Thank you for your email received by us on 21 November 2018 asking for information about dimensions of all train tunnels used on the London Underground.

Your request has been considered in accordance with the requirements of the Freedom of Information (FOI) Act and our information access policy. You asked for:

in a digital form, information on the dimensions of the train tunnels on the London Underground? If possible I would like information on all tunnels that are still in use, and some way of identifying them, e.g. the dimensions of the tunnels on each line. I don't need the lengths of tunnels, but the diameter and height from the floor to the roof would be excellent.

I can advise that information on the sizes of platform tunnels and tunnels between stations can be found in the book ‘Rails through the Clay’.

In accordance with section 21 of the FOI Act, we are not obliged to supply you with a copy of this part of your request as it is already accessible to you elsewhere.

However, to provide all of information you have requested would exceed the ‘appropriate limit’ of £450 set by the Freedom of Information (Appropriate Limit and Fees) Regulations 2004 because it is not held in a single repository and would require the manual reviewing of numerous files to review and extract the relevant material on areas where tracks diverge as well as details of all enlargements at subterranean junctions, for example.

Under section 12 of the FOI Act, we are not obliged to comply with a request if we estimate that the cost of determining whether we hold the information, locating and retrieving it and extracting it from other information would exceed the appropriate limit. This is calculated at £25 per hour for every hour spent on the activities described.

To help bring the cost of responding to your request within the £450 limit, you may wish to consider narrowing its scope so that we can more easily locate, retrieve and extract the information you are seeking. If you want to refine your request or make a Freedom of Information Act request in future, please bear in mind that the Freedom of Information Act allows you to request recorded information held by us. You should identify the information that you want as clearly and concisely as you can, specifying the types of document that you are looking for. You might also consider limiting your request to a particular period of time, geographical area or specific departments of the organisation.

Although your request can take the form of a question, rather than a request for specific documents, we do not have to answer your question if it would require the creation of new information or the provision of a judgement, explanation, advice or opinion that was not already recorded at the time of your request.

Please note that we will not be taking further action until we receive your revised request.

In the meantime, if you have any queries or would like to discuss your request, please do not hesitate to contact me.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely

Jasmine Howard
FOI Case Officer
Information Governance
Transport For London