The National Audit Office (NAO) has analysed why the beleaguered Crossrail project has needed £2.8bn of additional financing, citing over optimisim as a major factor.
'A compressed schedule, the contractual model, the loss of downward pressure on costs, and the absence of an achievable plan were set against an atmosphere where “can do” became unrealistic,' it said.
The previous funding of £14.8bn in 2010 has been the subject of renegotiation - with the current envelope set at £17.6bn including contingency. This is an increase of 19%, although at March 2019 Crossrail Ltd expected the overall programme to cost around £17bn.
'However, Crossrail Ltd has not yet completed its assessment of the impact of this opening schedule on costs and it is still unclear when the full Elizabeth line [as it will be called on launch] service will start. Crossrail Ltd must now focus on completing its plans and delivering against them,' the NAO said.
Financial rating agency Moody's has estimated that Transport for London (TfL) could lose up to £1bn in fare revenue as a result of the delay on opening - now estimated to be between October 2020 and March 2021.
Crossrail Ltd made mistakes that drove up costs such as carrying out train testing early 2018 that was 'of limited use and took any spare time and space from construction workers on site'.
The main issue appears to have been a fixation and over confidence around the planned December 2018 start date, which saw risks ignored or downplayed until too late.
Amyas Morse, head of the NAO, said: 'Throughout delivery, and even as pressures mounted, Crossrail Ltd clung to the unrealistic view that it could complete the programme to the original timetable, which has had damaging consequences. DfT and TfL must support the new Crossrail Ltd executive team to get the railway built without unrealistic cost or time expectations.
'While we cannot make an overall assessment of value for money until Crossrail is complete, there have been a number of choices made in the course of this project that have clearly damaged public value.'
Crossrail 'reduced the size of its central programme and risk management teams during 2018, in anticipation of the programme reaching completion in December 2018' and as result is currently attempting to rehire these personnel.
London Assembly Transport Committee, Caroline Pidgeon MBE, said: 'This report from the NAO reinforces our findings that bad management of Crossrail caused huge damage.
'Going forward Crossrail, TfL and the mayor must be realistic, pragmatic and honest with themselves and Londoners about any issues that occur and deal with them accordingly. They should not be afraid to face the music if a big stumbling block threatens the timing of delivery.
'Crossrail is a huge and complex project and it is understandable that not everything will go to plan. However, we must leave behind the days of chasing an opening date and focus on the successful delivery of a new line for Londoners.'