Question to the Department for Transport:

To ask Her Majesty's Government, further to the Written Answer by Baroness Sugg on 4 April (HL14781), what estimate they have made of the (1) cost, and (2) time delay, to an individual motorist as a result of the 50mph speed limit on the M4 road works between Junctions 3 and 12; and what they estimate the comparable cost of a minute’s delay for an individual travelling on an intercity train to be.

Highways England does not hold data in the format requested. The Economic Assessment Report provides a high-level estimate of the user delay costs, as provided in my answer of 4 April.

The Department for Transport also has guidance on economic appraisal of the impacts of unplanned rail delays and temporary timetables associated with engineering work. Estimates will vary based on demand levels, purpose of trips and rail fares.