§ Mr. Paul Marsden
To ask the Secretary of State for Transport if he will estimate the total reduction in vehicle kilometres that would result from a(a) 10 per cent., (b) 20 per cent. and (c) 50 per cent. increase in average vehicle occupancy. 
§ Mr. McNulty
It is estimated that the decrease in vehicle kilometres for cars, taxis and vans as a result of an increase in vehicle occupancy would be as follows:
Percentage increase in
10 20 50 Resultant percentage change in
-9 -17 -33 Vehicle kilometres by cars, taxis and vans (billion) Current (2002) 447 447 447 Following decrease in occupancy 407 373 298 Change -41 -75 -149
This assumes that the occupancy increase is a result of increased trip sharing and therefore fewer trips, and not, for example, from a shift of passengers from other 1774W modes of transport. It is also assumed that an increase in occupancy does not result in an increase in trip length (i.e. passenger kilometre figures stay fixed).