presents a time series regression model to estimate annual passenger demand for the State Railway of Thailand (SRT). The model was developed for a time period of 15 years (1974–1988), incorporating such variables as the country's gross domestic product (GDP), SRT passenger fares, competing intercity bus fares, and a dummy variable of the Fifth National Five Year Plan advocating a railway-favored modal shift policy. This simple but useful model analysis estimated the demand elasticities