Question to the Department for Transport:

To ask the Secretary of State for Transport, what estimation she has made of the percentage of traffic on the M25 that is related to Heathrow Airport.

The Department does not have robust observed estimates for the proportion of traffic on the M25 that is related to Heathrow Airport, as it is difficult to disaggregate this from available data. For example, passenger data does not translate to an estimate of the number of vehicles to/from the airport as some passengers will travel in the same vehicle and does not include vehicles travelling to the airport without passengers, for example freight.  The proportion of traffic on the M25 travelling to or from Heathrow will vary along the route, with the highest proportion closest to Heathrow.