The first of London’s new air-conditioned DLR trains has returned to service after 10 months off the tracks.

It follows a summer of back-to-back heatwaves in the capital, which left passengers sweltering across London’s transport network, as temperatures reached 37C on some Underground lines on the hottest days.

The return of the first of 54 new air-conditioned trains is therefore likely to come as welcome news for many commuters.

The trains were initially introduced in September 2025 but were taken out of service just six weeks later, in November 2025, as a precautionary measure after one of the automated units overshot a station platform during wet weather.

Their withdrawal meant passengers went through the summer without the new air-conditioned fleet as London was hit by repeated spells of hot weather.

Engineers traced the issue to a fault with the braking software under low rail adhesion conditions.

Now, after the completion of modifications and "a comprehensive programme of testing", the trains are gradually being reintroduced — with TfL monitoring their performance closely.

TfL says changes have been made to the trains’ braking systems and equipment has been installed to improve grip between the wheels and the track.

The transport authority apologised for the delay to the rollout, reiterating that the safety of passengers across its network was its top priority.

Stuart Harvey, TfL’s Chief Capital Officer, said: "We're pleased that the first of our new DLR trains has returned to customer service following the completion of a thorough programme of modifications, testing and assurance.

“Safety is always our top priority, and we took the decision to remove the trains from service as a precaution while we worked with CAF to investigate the issue and implement a solution.

“I apologise for the delay in reintroducing the trains but am pleased this marks an important milestone in delivering a modern new fleet for the DLR.

“As we begin the phased reintroduction of the trains, customers will start to benefit from more spacious and accessible journeys, while we continue to monitor performance and introduce further trains into service."

Data shared with The Standard showed how Londoners changed the way they travelled during what has been a record-breaking hot summer in the capital.

Uber Boat by Thames Clippers and e-bike operators saw a sharp rise in passenger numbers this year as Londoners sought more comfortable ways of getting around the city during periods of extreme heat.

Meanwhile, the figures appeared to suggest passengers switched from some of the deeper, hotter Underground lines to Overground services during the months of July to August.

The new state-of-the-art trains feature spacious walk-through carriages, live travel information, air conditioning and enhanced accessibility features, including dedicated wheelchair spaces and mobile charging points.

Capacity on the trains is increased by 10 per cent and the new fleet will eventually replace the oldest DLR trains, some of which have been in service for more than 30 years.

The phased reintroduction of the fleet will begin on the Stratford International to Woolwich Arsenal route.

Commenting on the rollout, the Mayor of London, Sadiq Khan, said: "This is an exciting day for east and south London, as the first new state-of-the-art DLR train enters service.

“These modern new trains are fantastic and will transform travel for millions of Londoners, significantly improving comfort, accessibility and reliability. The additional capacity will also support further growth, particularly in parts of the Royal Docks and the Isle of Dogs where the DLR is the most-used mode of transport, supporting new jobs and homes.

“I'm committed to modernising London's transport infrastructure, which is vital to delivering quicker, greener and safer journeys that are accessible to all."

The number of trains in service will increase gradually through the controlled introduction of additional trains.

Further details will be released in due course.