Sadiq Khan and London’s transport commissioner, Mike Brown, announced the plans which will allow the freeze to come into force without hitting vital investment on the transport network.
Khan, said: "Londoners currently pay some of the highest public transport fares anywhere in the world. My fares freeze on TfL services will make life easier for millions of people and will ensure that London becomes a more affordable city for all."
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However, the mayor also laid out the limitations of the new fares freeze, which will cover only single and Pay As You Go fares.
Commuters using daily or weekly travelcards, or using the systems up to the daily limit, could still face increases, as these were priced to include services outside the TfL network.
Liberal Democrat London Assembly Member hit back at plans: "Khan’s manifesto specifically said that Londoners won’t pay a penny more for their travel in 2020 than they do today. There were no ifs, or buts, in that statement."
"The reality is that many Londoners will see their travelcards rise over the next few years. What we have found out today feels like a very early broken promise from London’s new Mayor."
Freezing fares was a major manifesto pledge of Khan in the build-up to the London mayoral election, and one that opponents said that he wouldn't be able to achieve without risking vital improvement works.
The value of a fares freeze – until May 2020 – is estimated by TfL to be around £640m over four years.
London Conservatives have responded by accusing the mayor of u-turning on his flagship policy.
“By raising Travelcard prices by inflation and breaking his biggest promise he is turning his back on those who showed faith in him," Conservative group leader Gareth Bacon said.
"Sadiq Khan was asked about his fares freeze thousands of times during the Mayoral campaign. Not once did he mention that this freeze would not include Travelcards.
"Clearly he was happy to say anything to get elected and now he’s Mayor he’s very happy to ignore any promise that is inconvenient. He should now come clean with Londoners about which parts of his manifesto were not worth the paper on which they were printed."
Cost-savings to fund the freeze include:
- A fundamental review of TfL’s organisational structure to review management layers and eliminate wasteful duplication across all its functions, including bringing together engineering operations and IT departments (estimated saving £20-25m).
- Improved procurement and renegotiation of contracts from suppliers and other third-party spending which accounts for over two thirds of TfL's total budget (estimated saving £50-60m).
- The reprioritisation and consolidation of IT projects which delivered relatively low benefits (estimated saving £20-30m).
- Freezing recruitment for all but the most essential roles and significantly cutting the most expensive of the existing circa 3,000 agency contractors currently engaged by TfL. A reduction of over 100 IT contractors alone will save around £2m.
The move comes after Khan introduced the one hour "hopper" bus fare, where passengers will be able to take two journeys in one hour but still pay one fare.