Transport for London wants to double the number of Elizabeth line trains serving Heathrow airport’s Terminal 5, The Standard can reveal.
At present, only two “Lizzie line” trains an hour arrive at and depart from the biggest and busiest of Heathrow’s terminals, which handles about 40 per cent of all airport passengers.
But TfL commissioner Andy Lord has asked officials to explore the feasibility of doubling this to at least four trains an hour.
He said this would benefit passengers - and also the thousands of people working at Terminal 5, which opened in 2008.
However he admitted it could be technically difficult to achieve, as the new trains would need to be integrated into existing service patterns across the rest of the Elizabeth line - and on Network Rail infrastructure west of Paddington and east of Liverpool Street, where they share track with other train companies.
An additional 10 Elizabeth line trains are due to enter service in 2026 to boost capacity on the often packed line. Mr Lord told the TfL board that there were “a number of options on how we deploy those trains”.
Heathrow’s terminal 2/3 train station is served by six Elizabeth line trains an hour. These then branch off – four to Terminal 4 and two to Terminal 5.
But TfL data shows that Terminal 5 has more than double the number of Elizabeth line passengers than Terminal 4 – 3.455m for the 12 months to mid-January, compared with 1.685m for T4.
A total of 11m passengers get on or off at Terminals 2/3, meaning the Lizzie line now carries in excess of 11m passengers to or from the airport each year.
This is almost as many as the 12.5m who use the cheaper and more frequent but slower Piccadilly line service on the London Underground.
The £20bn Elizabeth line has also attracted passengers from the more expensive but quicker Heathrow Express, which runs a direct shuttle service between Paddington and the airport every 15 minutes.
The Heathrow Express has seen passenger numbers decline by eight per cent year on year, according to the Office for Rail and Road figures to last September.
Over the same period, the Elizabeth line has seen a 10 per cent increase in passengers across its 41 stations, consolidating its place as the best-used railway in the UK.
More than 500m journeys have been made on the Lizzie line since it finally opened, years late and over budget, in May 2022.
Mr Lord, who used to work at Heathrow for British Airways, said TfL had not realised how many passengers would transfer to the Elizabeth line from the Heathrow Express, “which is good for us”.
He said the airport had returned – and surpassed – pre-pandemic levels of passenger journeys.
Heathrow handled 83.9 million passengers in 2024 – three million more than its previous record that was set in 2019.
Mr Lord said: “Clearly Heathrow is back at high numbers, so we are going to do some further work around what their assumptions are and what does that mean for us.
“We only serve Terminal 5 with two services an hour. I’m challenging the team on what more we can do to review that.
“We do know that 30 per cent of all journeys on the Elizabeth line are new journeys, because we have now got connections from Essex to west of London, which previously you could only realistically do in the car.
“There are some wider conversations [to be had] with Heathrow and DfT and Network Rail around what does the future provision of services to the west of London look like.”
Speaking to The Standard, Mr Lord said: “The Elizabeth line is proving extremely popular with passengers and staff working at the airport.
“We currently only serve Terminal 5 twice an hour. I think there is a case for us increasing that. I have asked our teams to see what is possible.
“I think that would be complementary to the existing Heathrow Express service, and would deliver real benefit to the airport as well as our ridership and give customers who are arriving and departing from Terminal 5 a greater choice.”
Heathrow is expected to come forward with new plans for a third runway this summer.
Sir Sadiq Khan, the mayor of London, who opposes the third runway plans, says Heathrow would be expected to cover the cost of new public transport links to the new terminal that a third runway would probably need.
Asked about the airport’s expansion plans, Mr Lord said TfL would “have to wait and see” what was proposed.
“Clearly if the airport does get approval to expand, we will need to significantly increase the public transport proposition, rail capacity, bus capacity, active travel – and we would need to understand how Heathrow would pay for that,” he said.
