To ask the Secretary of State for Transport, what proportion of the tunnelling works for High Speed Two in Buckinghamshire will pass through earth classified by the British Geological Survey as (a) white chalk subgroup, (b) grey chalk subgroup and (c) any other soils.
18 February 2019
a) approximately 14,200 metres of the tunnels pass through a white chalk sub-group
b) approximately 1,000 metres of the tunnels pass through a grey chalk sub-group
c) approximately 200 metres of the tunnels pass through other soils (clay with flints)