The new Piccadilly line trains, which will transform journeys for millions of customers on one of the Underground’s busiest lines, will begin operating in the second half of 2026. These new trains offer ten per cent more capacity, walk-through air-conditioned carriages, wider double doorways for easier boarding, real-time digital displays and on-board CCTV for added security. The trains are lighter than existing designs, which means they are more energy efficient and provide a smoother ride for customers, consuming 20 per cent less energy.
This is an ambitious upgrade programme with the most complex train that has ever been introduced onto the Tube network. It will bring transformational benefits to millions of customers but also involves engineering challenges in designing, building and introducing these new trains onto one of the deepest and longest lines on TfL’s network, while ensuring they are fully integrated with London Underground infrastructure. The pioneering train is the first Deep Tube train to have air conditioning; a feature that can only be achieved because of the novel space-saving design techniques that allow the air conditioning to be placed under the train.
Since the first train was delivered to London, 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. As a result, the start of a rigorous programme of testing the interactions with the infrastructure and systems has had to be rescheduled. Siemens Mobility and TfL have been working together to address these issues, which will allow testing to start in the summer. All mitigations or design alterations will be incorporated into all future trains.
Once testing starts, enough time is needed to fully test the complex interactions between the new train and some of the oldest infrastructure on the Tube to ensure the trains are safe and reliable for passengers. Given the complexity of introducing this novel train into a railway that is more than one hundred years old and that is shared with other trains at some locations, it is expected that there will need to be time to address any issues identified. This is to make sure the train is safe and reliable for passengers. Without the testing of the train and infrastructure together in London, this work cannot start.
Stuart Harvey, TfL’s Chief Capital Officer, said: “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.”
Sambit Banerjee, Joint CEO at Siemens Mobility, said: “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.”
The recent funding settlement from the Government will ensure that London’s transport network can continue to support new homes, jobs and economic growth in the capital and across the UK. It will mean that TfL can complete the introduction of the new innovative trains on the Piccadilly line as well as progressing discussions on new Bakerloo line trains.
