Past attempts to devise rational design methods for transit services (such as the "total cost minimum") have encountered the difficulty that they require the assumption of a constant demand for service despite the fact that demands are ordinarily assumed to vary with levels of service. If a design rule is employed which specifies at least one service attribute (say, headway) as a strictly monotone function of route patronage, this difficulty can be overcome by expressing the demand function in terms of this attribute. We then have the actual patronage as a function of the service attribute and the service attribute as a function of the anticipated patronage, and may solve for equilibrium points at which actual patronage equals anticipated patronage. For most plausible combinations of headway design rules and demand functions, two cases are likely: there may be either two equilibrium points or none. Examination of the way in which trip disutility should vary with anticipated patronage reveals that trip disutility is not very sensitive to errors in demand estimates for high-patronage routes, but that sensitivity increases as patronage decreases. As it appears that rational design methods would be most beneficial for low-patronage systems, lack of accurate route-specific demand models constitutes an important barrier to their use. For the covering abstract of the symposium see IRRD 284351. (Author/TRRL)

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 44-64

Subject/Index Terms

Filing Info

  • Accession Number: 00452548
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0 8020 2461 0
  • Files: ITRD, TRIS
  • Created Date: Apr 30 1986 12:00AM