Transport for London (TfL) initially estimated the costs of this scheme to be £120-180m in 2016 prices. This was based on an initial understanding of the scheme and some very outline design proposals benchmarked against other schemes of a similar nature.
This is an incredibly complicated scheme – in many ways unprecedented. Once TfL developed full designs, construction and operational plans, as well as a developed cost estimate, it became clear that the costs were likely to be significantly in excess of original cost estimates. I therefore fully support the difficult but pragmatic decision that TfL took in determining this scheme is unaffordable at this time. This is further explained in my response to Mayor’s Question 2020/4646 and TfL’s cost estimate for the scheme is explained in my response to Mayor’s Question 2019/19609.