Sir Sadiq Khan is coming under pressure to speed up the rollout of air conditioning on the Tube as London frazzles in its second heatwave of the year.
As temperatures soared towards 40C on Wednesday, the Mayor of London was urged to sort out delays in new rolling stock with air con for the Piccadilly line.
Opposition politicians also stressed that this must be a step towards air conditioning on the whole of the Underground network as the capital faces hotter weather due to climate change.
The first of 94 new Piccadilly trains had originally been expected to enter service late last year and to bring in air con for the first time on a deep Tube line.
But this was first put back into the second half of this year and is now expected to happen between December and June next year.
The rollout of 54 new trains with air conditioning started on the DLR last autumn but was halted after one of them stopped past its intended stopping point.
The delays to the two new rolling stock programmes mean that there have been no new trains with air con introduced on the Underground for nine years.
Conservative London Assembly Member Thomas Turrell said: “Londoners could have been enjoying air-conditioned Piccadilly and DLR trains this week, but instead they are sweating to death because the Mayor has failed in this basic responsibility.
“If by next summer we are still in this position, the Mayor will have undoubtedly failed Londoners in his mission to keep them safe and comfortable on public transport."
Currently, there are 192 air-conditioned Tube trains, out of 620, covering 40 per cent of the network.
Caroline Russell, Leader of the Green Group on the London Assembly, stressed: "With sweltering temperatures becoming more common, London is expected to develop a climate comparable to southern European cities, such as Barcelona, over the coming years.
"We need air conditioning on every Tube and train to keep passengers and staff safe during periods of extreme heat.”
Four lines currently have air conditioned trains including the Circle, Hammersmith & City, District and Metropolitan, as do the Elizabeth line, Overground, Northern City, Thameslink and trams.
The Tube lines without air con are the Central, Bakerloo, Jubilee, Victoria, Waterloo & City, Piccadilly and Northern.
Liberal Democrat transport spokesperson Olly Glover MP said: “With four lines on the Underground network running with trains over 30 years old, including the Central Line, one of the busiest, warm words and advice about looking out for each other simply doesn’t cut it.
“Sadiq Khan must urgently address these chronic issues and accelerate the rollout of air-conditioning across the network and look to our European neighbours with similar transport networks, such as Madrid, who have experience of this.”
Londoners are also having to endure sweltering conditions at Tube stations with cooling equipment unable to cope with heatwaves.
More than a decade ago, systems were upgraded at Oxford Circus, with chiller units to blow out cool air, and cold water from a borehole was being piped into units to reduce the temperature at Green Park.
But the cooling element failed at Oxford Circus in 2017, with a similar situation at Green Park.
Fans are installed in some stations to reduce temperatures.
But Transport for London (TfL) said it was prioritising conditions for passengers on trains.
It added that the “short-term and stop-start” nature of funding over recent years had meant taking “difficult decisions” and “carefully prioritising” investment.
Nick Dent, TfL’s director of customer operations, stressed: “We’re working to ensure our transport services remain resilient in the face of more extreme and frequent hot weather events.
“We are investing millions as part of our continuous work to improve the network, which includes introducing new trains to meet growing customer numbers whilst providing more comfortable journeys.”
He added: “We have implemented energy efficient solutions on new trains, which reduce the heat generated.
“We’re constantly looking at how innovative solutions can be rolled more widely on the transport network to ensure more passengers experience cool and comfortable journeys in the summer.”
TfL says the delay to the new Piccadilly trains was due to "the complexity of introducing entirely new trains onto ageing infrastructure", with some parts of the line some 120 years old.
