Modeling of Vehicle Ownership: Case Study of Thailand

Document Type

Journal Article

Publication Date


Subject Area

infrastructure - vehicle, land use - planning, ridership - demand, ridership - growth, mode - bus, mode - bike


Trucks, Travel models (Travel demand), Travel demand, Transportation policy, Transportation planning, Thailand, Road freight vehicles, Regression analysis, Regression, Motorcycles, Motor coaches, Mathematical models, Lorries, Heavy goods vehicles, Economic growth, Case studies, Cargo vehicles, Buses, Automobile ownership


This paper aims to address some important issues concerning the rapid growth in vehicle ownership and how different types of vehicles interact, especially in a country undergoing rapid economic development, such as Thailand. The forecasts of such growth are important for road building, traffic management, strategic transport decision making, travel demand forecasts, and other policy issues at the regional and national level. For those reasons, a series of vehicle ownership models that include (a) car, (b) motorcycle, (c) truck and heavy goods vehicle, and (d) bus and coach models is proposed, developed, and presented. These models are built on limited aggregate data, both time series and cross-sectional, and are disaggregated spatially by province, with non–log-linear weighted least squares regression. Basically, the inputs required are forecast gross provincial products per capita and population level. The model of vehicle ownership is applicable to the conventional four-stage transport model as an add-on before the trip generation stage. All proposed models have good statistical properties, that is, all statistically significant coefficients and high adjusted R² value and good fits within 12% of observed values during the base years. The model of car ownership gives reasonable income elasticities regarding car ownership and a sensible saturation level when compared with other studies. The forecast for a case of increasing income shows that the car ownership level will increase together with the truck level. However, as people own more cars, motorcycle and bus ownership levels will decrease.