Abstract
The authors develop a joint model for the demand for travel and the demand for travelcards on the London Regional Transport network. Tests indicate that the theoretical restrictions are broadly satisfied, although the Slutsky symmetry condition is strongly rejected. The estimates confirm previous findings that underground travel is inelastically demanded while the demand for bus travel is elastic. A simulation analysis attributes between one third and one half of the rise in demand for underground travel in the period 1982-87 to employment growth; and between one half and two thirds to the introduction of travelcards.(Author/publisher).