Transport for London (TfL) has confirmed that its new fleet of Piccadilly line trains will begin carrying passengers in the second half of 2026. The upgraded trains promise greater capacity, improved comfort, and enhanced reliability on one of the Underground’s busiest lines.
Built by Siemens Mobility, the new trains feature walk-through, air-conditioned carriages—an Underground first for deep-level lines—alongside wider doors, digital passenger information systems, onboard CCTV, and a smoother ride. Designed with energy efficiency in mind, the trains will consume 20% less energy than current models.
Piccadilly Line trains: Testing phase begins Summer 2025
TfL plans to begin infrastructure and systems testing on the new trains this summer. This follows initial assessments which revealed that integrating the modern vehicles into the 100-year-old network is more complex than expected. Testing will ensure compatibility and allow for any necessary design adjustments to be made before passenger service begins.
“We’re proud and excited that these innovative new trains on the Piccadilly line will have a transformative effect for London. This hugely complex project will boost capacity and make journeys more accessible and more comfortable for millions of people. This is an ambitious project with new 21st century trains providing engineering challenges in both building and introduction into service on a 20th century railway and it is critical that we ensure that safety comes first and that the trains are in top condition when they begin to service London.
It will obviously be disappointing for customers that they will have to wait a bit longer for the new trains, and I regret that. But I would like to assure Londoners and visitors to our city that we are working extremely closely with Siemens to ensure that the new trains can be introduced as soon as possible in the second half of next year,” Stuart Harvey, TfL’s Chief Capital Officer, said.
He acknowledged delays but reassured the public that the trains would enter service as soon as safe and reliable operation could be ensured.
The wider Piccadilly line upgrade supports nearly 1,000 skilled jobs at Siemens’ Goole facility in Yorkshire. The new fleet is a key component of TfL’s long-term strategy to improve reliability and passenger experience across the Underground.
“We’re working really hard with TfL to deliver the new Piccadilly line trains that are going to transform travel for people in London. Any project like this is complicated – we’re bringing state-of-the-art, air-conditioned, walk-through trains into tunnels that were built 120 years ago.
We’re sorry we can’t have our innovative trains running for passengers even sooner but, once they’re in service, the technology on these new trains will bring smoother, greener and more comfortable journeys for Londoners for the next 30 or more years,” Sambit Banerjee, Joint CEO at Siemens Mobility, added.
Following testing, the trains will be introduced gradually from late 2026. The recent government funding agreement will allow TfL to complete the Piccadilly line upgrades and begin preparations for renewing the Bakerloo line fleet as well.
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