| Abstract | Thailand has developed and expanded the country's transportation system in order to facilitate economic activities. During the third plan emphasis was placed on road transportation. Thus, the road transportation network has expanded from 8500 kms in 1961 to 30000 kms at present. This expansion of roads has supported the intra and inter regional goods movement activities. the study gives the models on demand for trucks based on different commodity movement, and trips generated by present cargo quantities.
For the study, secondary data were collected from various sources of Thailand, and models were developed by Box-Jenkings, Regression, and GMDH methods. The obtained models were compared using the error percentage thus computed. The study had considered three types of vehicles which are mostly used in the country. They are tenwheel, sixwheel, and medium sixwheel trucks.
Analyzing the data it was found that Box-Jenkins models are better in forecasting the demand for different types of truck. Besides, GMDH and regression forecasting models were found to be better in forecasting the yearly demand for all types and tenwheel trucks, respectively, with the presence of variables like national development budget, chemical products, agricultural products, exports, etc. Because of high population and expansion of metropolitan area truck trips with cargoes like construction materials, agricultural products, food products, etc., inbound to Bangkok, are higher than the truck trips going out from Bangkok with cargoes like petroleum products, fertilizers, and other industrial products. Thus, trucks will be returning back with out cargoes after entering Bangkok. |