Question to the Department for Transport:
To ask Her Majesty's Government how HS2 will ensure the stability of the tracks when they pass over large sink holes in the areas of old mine workings; when a detailed geological survey will be done in those areas; and how the track alignment and levels will be maintained in areas where continuous settlement is likely.
HS2 Ltd is following an established process of risk management to ultimately ensure the stability of high-speed rail infrastructure in all areas. This includes detailed desk study (the acquisition and interpretation of existing available data), field investigation including geological survey, interpretation of ground conditions, design, construction and maintenance through operation.
At each stage the level of site-specific knowledge increases and the risk is reduced. Mining-related hazards will be investigated within this process, and will be mitigated. Voiding in the ground due to the presence of mineworkings is such a hazard, since if left untreated it could result in sinkholes.