This paper investigates the relationship between the quality of public transport and the extent of car ownership in different areas of London. En passant, it also takes a hard look at some of the more general issues involved in car ownership forecasting. Data from the London transportation study of 1962 is used to develop a model relating car ownership to: (a) household income; (b) household size; (c) public transport availability. This proves capable of explaining 80% of the observed variations in car ownership between different areas of London. The model is justified behaviourally by means of a system analysis of the set of relationships that influence car ownership. A model using household income and net residential density to explain car ownership is tested but proves no better statistically and is far less reasonable behaviourally. It is also shown that, even in a model incorporating both public transport quality and density, public transport quality remains a statistically significant factor. The inability of the income - density models developed by the department of the environment to predict accurately the increase in car ownership that occurred during the 1960s is examined and a possible explanation for this put forward: it is suggested that while density can be shown to be an excellent proxy for the relative attractiveness of public transport in a cross-sectional study, it cannot reflect, for example, the decline in the attractiveness of public transport which occurred during the 1960s. Some evidence in favour of this hypothesis is set out and possible validation methods proposed. It is concluded that great care is needed when applying cross-sectional results temporally and that system analysis deserves far more attention in this field than it has often received. Some of the consequences for transportation planning of significant feedbacks to car ownership from the factors that determine modal split are discussed: in particular, the need for public transport quality to play a larger and more active role in transportation modelling than hitherto. (TRRL)

  • Corporate Authors:

    London Transport Executive

    Commerical and Planning Department, 55 Broadway
    London SW1,   England 
  • Authors:
  • Publication Date: 1974-1

Media Info

  • Features: Figures; References;
  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00303007
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Report/Paper Numbers: Oper Res Rpt. R 203 Monograph
  • Files: ITRD, TRIS
  • Created Date: Jan 30 1980 12:00AM