They said the new line is projected to generate £1.388 billion in its first next three years - rather than the £2.410 billion anticipated in Transport for London’s 2019 business plan.
They said the dramatic fall in expected fares revenue was due to the long-term impact of Covid and changes to working patterns, with more people likely to continue working from home.
Crossrail will be renamed the Elizabeth line when it finally opens by the end of June - almost four years late and billions over budget.
Simon Kilonback, TfL’s outgoing chief financial officer, said Crossrail was expected to generate £262m in 2022/23, rather than the £489m initially hoped.
In 2023/24, it is expected to generate £516m rather than £884m, and in 2024/25 the income is projected to be £610m rather than £1,037m.
This means the revenue raised over the next three years will be less than 60 per cent of that hoped pre-pandemic.
The London Assembly budget committee was told on Friday that TfL only expects passenger numbers across all services to reach 82 per cent or pre-pandemic levels in 2022/23.
Its budget assumptions assume that Crossrail’s central section – linking Liverpool Street and Abbey Wood with Paddington – will be open by June 26, though the exact opening date is likely to be earlier.
TfL commissioner Andy Byford said the “trial operations” phase was about 40 per cent complete and only two stations remained to be finished.
He expected Canary Wharf station to be handed over “within a matter of weeks” but said Bond Street station was “around three months behind schedule”.
He said a period of “ghost running” of the new trains would be carried out – running a full service without passengers – to ensure it was reliable before it was opened to the public.
Mr Byford said of the plans to open the line in the first half of 2022: “It has not slipped on my watch. It will not slip on my watch. It will be the first half of 2022.
“No-one – yourselves, Londoners – will thank me if it’s unreliable. We are not going to rush it. We will be obsessing about getting the railway right. I will give the ‘go’ once I’m certain it can open flawlessly.”
He repeated his hope that the opening of the central section will quickly be followed by a “hybrid” system allowing trains from Shenfield to run through to Paddington from September, rather than having to terminate at Liverpool Street.
The full line will eventually enable passengers to travel from Reading and Heathrow through central London to Shenfield or Abbey Wood without needing to change trains, once services are integrated with the National Rail timetables in December 2022 and May 2023.