This paper tests the elasticities to time, frequency and interchange implied by an approach which combines these three variables into a single term and compares this approach with models which estimate separate elasticities. The forecasts obtained from different model forms can be appreciably different
Topic: 19. Demand
The authors formulate and estimate a model of international air travel demand for Israel. Consumers’ wealth is found to be a significant determinant and failure to include it in the estimated equations yields price elasticities which are biased downward and income elasticities which are biased upward.
It is concluded that aggregate approaches to forecasting demand may be appropriate for cheap investments, such as new stations, or an initial assessment of a wide range of options. For detailed consideration of expensive investments, such as new rail services, disaggregate methods based on RP and or SP data should be considered.
The authors develop a joint model for the demand for travel and the demand for travelcards. The estimates are that demand for underground travel is inelastic while the demand for bus travel is elastic. 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.
Separate models for business and non-business rail trips of over 50 miles show wide variations between different groups of the population. The author examines the effects of such factors as socio-economic group, age, household type, car ownership and access to a main line station. Some results are unexpected.
The authors examine twenty London-based rail flows over the period 1973 to 1984. On the whole, the influence of the external environment was neutral; fares, quality of service and competition were more important. The results show a remarkable degree of consistency and precision.
The author’s model is successful in predicting short-term demand. Demand is inelastic, but is influenced by fares, consumer expenditure and seasonality.
Demand is found to be strongly influenced by rail fares and journey time, by the level of competition from coach and car, by cyclical activity, and by seasonal factors.
Demand for energy by the transport sector does respond to changing prices; but the response is small because energy accounts for only a comparatively small portion of transport costs.