As I’ve been keeping an eye on the Freedom of Information disclosure log on the Transport for London (TfL) website, I noticed that they have published a response to a member of the public who requested information regarding delays to the 2024 Tube Stock (also known as the New Tube for London) for the Piccadilly line.
This is a follow-up to my previous article, in which I reported on delays to the DLR rolling stock B23, now expected to enter service later in 2025.
The first test train for the new Piccadilly line fleet has arrived in
— TfL (@TfL) October 16, 2024
London 🤩🚆
This train will undergo intensive testing before the new fleet starts entering passenger service by the end of next year.
Find out more 👇https://t.co/KJZWXspHNO pic.twitter.com/0ix3MkEi5c
Request ID: FOI-1609-2526
Date published: 24 September 2025
As a concerned Londoner and regular user of the Piccadilly line, I am writing to express my growing disappointment with the continued delays to the Piccadilly line upgrade. Having read the 2 July 2025 update to the Programmes and Investment Committee, I have the following questions:
1. What exactly caused this latest delay?
The report mentions “challenges with design, build and commissioning” and a revised testing strategy. Can you please specify what those challenges were? Were they technical faults? Software issues? Infrastructure incompatibilities? Why weren’t these issues identified and resolved earlier?
2. Why has the first train been delayed by over a year since the last update?
In October 2024, we were told the first train would enter service by late 2025. Now, the new target is July to December 2026. What changed so drastically since October?
3. Why has it taken nearly 9 months just to prepare the train for system integration testing in London? The first train arrived in October 2024, yet testing on the actual railway won’t begin until August 2025. What has been happening during this period? Why is there no clear timeline showing the preparation stages?
6. When will we get a clear, fixed timeline for the entire fleet rollout?
This delay raises concern not just for the first train but for all 94 trains. When will you publish a reliable delivery schedule for the remaining trains and a timetable for when the Piccadilly line will increase from 24 to 27 trains per hour?
Answer: Introducing a fleet of 94 new state-of-the-art trains to one of the deepest and longest lines on our network is a hugely complex task. The first of the new Piccadilly line trains arrived in London in autumn 2024 to provide an opportunity for operational and maintenance teams to familiarise themselves with the train, and for the necessary assessments to be made before integration testing could begin on our network. Following their arrival, TfL's engineers have been able to assess the train on site. This has allowed them to identify and better understand the challenges for getting these new trains ready for integration testing and then for passenger service. This process has identified it is more complex than expected which meant we have had to reschedule our rigorous testing programme; this commenced in early August. Also, this means we will not be able to start introducing new Piccadilly line trains into service by the end of this year as previously communicated. We are working hard to bring the new trains into service safely and reliably as soon as possible so customers can begin to enjoy the benefits, now working to a window of between July and December 2026.
Large-scale infrastructure projects have complex reporting structures to ensure that any risks are identified as early as possible and mitigations are employed swiftly to address them, when necessary. These processes have needed to be worked through before it was appropriate to announce any changes to previously published information.
In accordance with the FOI Act, we are not obliged to supply more detail on the information you have requested as it is subject to a statutory exemption to the right of access to information, under Section 22 of the Act, which applies where there is a pre-existing intention to publish the information requested.
Further detail regarding these delays will be published once further negotiations have concluded and the information can be appropriately reported. This exemption is subject to a public interest test, which requires us to assess whether the public interest in applying the exemption outweighs the public interest in disclosure. In this instance, it is considered that the public interest favours the publication of this information, in context and according to the pre-determined schedule, rather than in response to your request, to ensure the information is provided accurately and in an accessible manner.
4. What have you learned from this experience, and how will future trains avoid similar delays?
The report says that “learning is being incorporated” from the first train. What specific improvements are being made? Will these ensure that the second and third trains will have smoother rollout?
Answer: Lessons from the first train will be incorporated into future strategy and will help us narrow down our six-month window for introducing the new Piccadilly line trains into passenger service, alongside benefiting other programmes such as the Bakerloo Line Upgrade.
5. Is this delay going to increase the overall cost of the programme? The estimated final cost (EFC) was £2.436bn in the October 2024 report. Has this figure changed as a result of the delay? If so, what is the new estimated cost, and will extra funding be needed?
Answer: We are currently in the process of undertaking a review of the estimated cost and an update will be provided to our Programmes and Investment Committee meeting once complete.
Just to clarify briefly, I did not make the Freedom of Information request, as TfL stated that they publish the response online without disclosing any personal information of the requester. A similar procedure applies with the ‘What Do They Know’ website, where anyone can submit a FOI request to a UK governing body, and the correspondence is available for the general public to view.
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