Crossrail chief executive Rob Holden has estimated that nearly £1 billion will have been spent on the project by the end of this year.
Speaking at London Rail 09 Conference he said: “By the end of this year costs will be starting to approach £1 billion.”
Mr Holden said that by the end of 2010 costs will have risen to £2 billion.
He pointed out that whilst these were large sums of money they were a fraction of the £15.9 billion allocated for construction of the project.
Mr Holden said that a great deal of time was being spent to ensure that Crossrail was not shelved for political reasons and if procurement for the project was rushed then it would “introduce different risks.”
He added: “We will procure when we’re ready.”