A feasibility study released last year by Highways England said the project would include a tunnelled section that could range anywhere between 20 and 30km. This would make it one of the longest road tunnels ever built and would raise a number of challenges (see Editor’s Comment, Tunnels and Tunnelling International December 2015, p.3).
The study is part of the government’s next phase of road improvements, which will get underway from 2020. The current Road Investment Strategy period covers 2015 to 2020.
In the final stage of the study, due to be completed by the end of 2016, the strategic and economic cases for each option will be assessed and cost estimates will be provided. Some speculation can be read in the comment previously referenced.