New Piccadilly Line Trains on Track for 2026 Launch: What’s Changing and What’s Still to Do

Londoners are one step closer to seeing a major upgrade on one of the city’s busiest Tube lines, as testing ramps up for the Piccadilly line’s long-awaited new train fleet.

The £3.2 billion investment—covering 94 new trains—marks a significant milestone in Transport for London’s (TfL) efforts to modernise its deep-level underground services.

What Makes These Trains Different?

These new trains will be the first deep-level Tube trains to feature air conditioning, offering a more comfortable journey for passengers. They will also be fully walk-through, allowing passengers to move between carriages—similar to what’s already in place on the Elizabeth line and some London Overground services. The upgrade also brings live customer information, improved accessibility, and a boost in capacity.

While air conditioning is already available on sub-surface lines such as the Circle and District, this marks a first for lines that operate in the narrow tunnels of London’s deep-level Tube network.

When Will They Arrive?

The first new train was initially expected to enter passenger service by the end of 2025. However, earlier this year, Transport for London confirmed a revised launch window between July and December 2026. According to TfL Commissioner Andy Lord, testing is going well, and the project remains on course to meet the updated timeline.

“I’m really hopeful we will continue to make progress for them to be introduced in the second half of next year,” said Mr Lord. “The trains are going to be absolutely transformational for customers on the Piccadilly line and visitors coming in to Heathrow too.”

So far, four trains have arrived in London, with three currently undergoing testing. The first one, a prototype, will return to the Siemens factory in Goole for modifications.

What’s Happening Behind the Scenes?

Extensive testing is underway to ensure the new trains can operate safely and efficiently on the existing Piccadilly line infrastructure. This includes compatibility with:

• Signalling systems

• Platform dimensions

• Tunnel clearances

• Train stopping points

• Power and communication systems

  
  

Initial tests, including weekend trial runs through central London between Northfields and Hyde Park Corner, have already taken place. Further testing is now progressing overnight during engineering hours and will soon shift focus to systems that involve real-time communication between the trains and line infrastructure.

TfL’s own programme reports confirm that integration is a complex process requiring updates to stations, depots, signalling, and train maintenance facilities.

Why the Delay?

Although earlier speculation pointed to tunnel size as a possible issue, TfL has firmly denied that the trains were incompatible with London Underground’s deep-level tunnels. Instead, the delays appear linked to the inherent challenges of designing, building, and commissioning a completely new fleet for a legacy system.

“This is extremely complicated and challenging,” admitted Mr Lord. “But testing is progressing well, and the teams are working incredibly hard to deliver a safe and reliable service.”

What Happens Next?

The full fleet of 94 trains is set to gradually replace the existing stock, which has been in operation since 1973. Once fully introduced, the frequency of service on the Piccadilly line is expected to increase from 24 to 27 trains per hour, further improving capacity on one of London’s key transport arteries.

TfL is also conducting a full cost review of the project, including updated timelines and infrastructure readiness.

In Summary:

• 🚆 94 new air-conditioned, walk-through trains are being introduced to the Piccadilly line.

• 📅 Launch now scheduled between July and December 2026.

• 🔧 Testing is ongoing with 3 trains currently active and 1 prototype undergoing modification.

• 🚧 Infrastructure upgrades across the line continue, including depots, platforms, and signalling.

• 🔄 Service frequency is expected to increase post-rollout.

With the first in-service journeys now under two years away, passengers can look forward to a more comfortable, efficient, and modern experience—marking the biggest change to the Piccadilly line in over 50 years.