THE DISTANCE TRAVELLED BY "SECOND CARS"

An increasing proportion of the growth in car ownership is made up of second cars, i.e. The addition of an extra car to a household that already has one. If the distance travelled by these cars is consistently different from the more common single car in a household, then future traffic levels cannot be assumed proportional to car ownership. However, the evidence on this shows substantial conflicts. Some data sources show that cars in two-car households are used substantially less than cars in one-car households. Other sources show exactly the opposite. The conflicting evidence is discussed, and some new figures given, leading to a reconciliation of the conflicts and some recommendations for research and application in traffic forecasting. (Author/TRRL)