FOI request detail

Signalling improvements

Request ID: FOI-0297-2223
Date published: 31 May 2022

You asked

As the signalling upgrade on the sub-surface lines is nearing completion, what effect has this had on the annual number of reported faults on the train describer and passenger information systems on these lines since 2015.

We answered

Our ref: FOI-0297-2223/GH

Thank you for your request received by Transport for London (TfL) on 10 May 2022 asking for information about signalling improvements.

Your request has been considered under the requirements of the Freedom of Information Act 2000 and our information access policy.

I can confirm that we do hold some of the information you require. However, to provide the information you have requested 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 requests 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. In this instance, we estimate that the time required to answer your request would exceed 18 hours which, at £25 per hour (the rate stipulated by the Regulations), exceeds the ‘appropriate limit’.

The fault data which is readily available only shows faults that are open, or were opened within the last 60 days. To begin to answer your request we would need to obtain historic fault data, for 45 sites over an 8 year period. If we were able to filter this information based on certain criteria, there would still be hundreds of line items that would need to be looked at to determine whether it is an item related to the signalling.

Other factors would need to be considered and analysed to respond to your request, such as:
  • Fault numbers are based on number of reported faults to the APCC
  • Individual station systems may have been upgraded during this time
  • Includes customer information faults that may not relate to the signalling system improvements e.g. display failures
  • Includes faults where no fault found – for example issue rectified itself overnight before technician attended
  • Not every platform used the new signalling immediately
  • Covid will have affected station reporting

Simply looking at the number of faults recorded would not give an accurate assessment of the situation – for example, for many of the sites, the earlier periods had the signs present but simply set to show nothing or a simple ‘Hammersmith & City Eastbound’ or similar, so faults were irrelevant and likely went unreported for longer. Since the upgrades, we have recorded display failures which would not be affected by signalling changes, we have localised faults to one station, and we have system faults that would relate to signalling (rather than Customer Information) that may end up with one job or multiple jobs called in. For example we had a system failure at Hammersmith SCC on the new system that we know caused a loss of information at 45 stations. We had around 16 jobs called, but the root cause was only one fault at one location.

We are therefore unable to readily advise ‘what effect the signalling upgrade has had on the annual number of reported faults on the train describer and passenger information systems on these lines since 2015, without a detailed analyse being carried out, which would take an excessive amount of time. Also the subsurface upgrade is not nearing completion – in terms of number of stations to be controlled by Thales signalling, we are at 45 stations out of 91 having just commissioned area SMA5.

Under the Freedom of Information Act, TfL does 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.

If you are not satisfied with this response please see the attached information sheet for details of your right to appeal.

Yours sincerely

Graham Hurt
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London

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