New air-conditioned Piccadilly line trains have been successfully tested in tunnels through central London after the launch of the fleet was postponed by up to a year.
Technical issues identified in prototypes delayed the launch as new trains had to be modified and re-tested to ensure they ran sufficiently.
The new trains had a test run between Northfield and Hyde Park corner during a closure of the Piccadilly line last weekend.
New Piccadilly line trains will replace older trains introduced in 1973 and will be the first of the Tube’s deep-level lines to have walk-through carriages and air conditioning.
Londoners have been calling on Transport for London (TfL) to install or improve air conditioning on Tubes, after temperatures reached up to 33C on trains during the heatwave in July.
The Tube lines which reach the hottest temperatures include the Victoria, Central, Bakerloo and Northern lines.
The Standard previously interviewed commuters on the Tube on the hottest day of the year in July. Salvatore Cafaelli, 60, who commutes on the Victoria line, said: “I have no choice, I have to take the Tube for work, but definitely it’s too hot. It’s like I am in a sauna.
“I think for the money commuters are paying, (TfL) should be improving the system,” he said – and called for air conditioning to be provided on all Tube lines.
The new Piccadilly train test run comes after The Standard revealed the arrival of the first 94 new trains which were due to be introduced into public service during 2025 had been delayed by up to a year – the new trains are now expected from July to December of 2026.
The initial delay was caused by unexpected difficulties in introducing the first new train onto challenging “real life” conditions on London Underground infrastructure, compared with the test track, on which the train is understood to have performed well.
The introduction of a new fleet of trains is part of a £2.9bn investment programme to upgrade the line.
Once the 94 new trains replace the existing 86 trains, TfL plan to increase the number of trains travelling through central London from 24 to 27 trains an every hour – equating to one every 135 seconds – at peak times.
The new trains are designed and manufactured by Siemens – the majority of the fleet is being assembled at the Siemens factory in Goole, Yorkshire.
At a London Assembly meeting, Andy Lord, the TfL commissioner previously admitted the introduction of the new trains was proving “challenging” and “extremely complicated” to fix.
Mr Lord said: “The first train was slightly late [arriving] in London last summer. Since it arrived, a number of issues have been discovered as part of testing that we have been undertaking in the depot.
“That has meant that Siemens have had to do some further design work.”
Stuart Harvey, TfL's chief capital officer, who is in charge of the introduction of the new trains, previously told The Standard: “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.”
