Estimating domestic aviation demand using the four-step travel demand model: a disaggregate approach

Abstract

Conventional aviation demand forecasting relies on the city-pair model, requiring historical Origin-Destination (O-D) traffic data and a mature network — conditions absent in developing economies and geographically compact island states such as Sri Lanka. Through a critical literature review, this study proposes an adaptation of the Four-Step Travel Demand Model as a city-pair demand estimation framework applicable to both existing aerodrome locations. A preliminary passenger profiling stage identifies traveller segments for whom air travel is feasible. Trip generation then estimates long-distance trip volumes as a function of household income, employment structure, population density, and tourism activity. Trip distribution constructs an O-D matrix using a gravity formulation with economic mass and tourism potential as attractiveness measures and generalised cost as impedance. Mode choice applies a disaggregate choice model within the Random Utility Maximisation framework, with utility specified across travel time, access time, service frequency, comfort, and cost. Route assignment is omitted as inapplicable at the city-pair level. Empirical validation through stated preference surveys, targeting aviation-feasible traveller segments across origin catchment areas, constitutes the essential next step.