TfL Ref: 2701-1920

Thank you for your request received by us on 4 December 2019 asking for information about London Underground delays.

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

a breakdown of the time difference, by London Underground line, between a delay beginning and the same delay being published on the official Twitter account for this line.

For example, if delays begin on the District Line at 17:45 and is first published on @DistrictLine at 18:05, this should count as 20 minutes.

I would like a breakdown by line for each month of 2019, containing the 25th, 50th, 75th, 95th, 99th and 100th percentiles

I can advise that we do not tweet every delay, rather we focus on communicating severe delays through Twitter. However, continuously updated service information is provided in our Travel tools section.

We also publish comprehensive details of London Underground’s performance at: https://tfl.gov.uk/corporate/publications-and-reports/underground-services-performance

In reference to Twitter, in many cases there is no electronic record of the delay as sources of information may be through a phone call or verbal message. For example:

• Information from the London Underground Control Centre (LUCC) is verbally communicated to a Twitter agent.

• A customer query prompts a Twitter agent to contact the LUCC for further details.

To obtain the information you are seeking would require manually comparing every tweet against every London Underground line delay recorded in an effort to produce the data you are seeking, which we do not hold in the format requested. Therefore to obtain this information would exceed the ‘appropriate limit’ of £450 set by the Freedom of Information (Appropriate Limit and Fees) Regulations 2004.

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.

If this is not the information you are looking for, or if you are unable to access it for any reason, 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