To ask Her Majesty's Government what assessment they have made of (1) the conclusions of the British Tunnelling Society in their 2019 article for Tunnels & Tunnelling International entitled ‘Tunnelling costs and production rates benchmarked’, which concluded that tunnelling costs decrease per unit length with increasing overall tunnelling length, and (2) the implications of these conclusions for estimates of the cost of the Wendover Short-Mined Tunnel Proposal on HS2 Phase One.
The Department for Transport has incorporated the Infrastructure and Projects Authority top-down benchmarking methodology for tunnelling, developed in partnership with the British Tunnelling Society, as part of the Transport Infrastructure Efficiency Strategy benchmarking initiative.
The proposal for the short-mined tunnel at Wendover was rejected by the Government in 2018. We do not believe that this historical decision would have been any different had this methodology been applied at the time. The decision to reject the proposed short-mined tunnel at Wendover was based on the estimated cost of mitigating the poor ground conditions in the area of the proposed tunnel.