Changes in commute patterns following an opening of a major mass transit system : a before and after study of Bangkok's Mass Rapid Transit Authority's Blue Line Subway
Abstract:
Stated preference (SP) surveying technique has been widely adopted in order to estimate models for predicting travel demand of a new transportation system. Prediction results, however, have been shown to be inaccurate. This research aims to develop SP models and evaluate their performance in travel demand prediction, using a case study of the Mass Rapid Transit Authority (MRTA)'s Blue Line subway in Bangkok, which consists of travel behavior surveys before and after the system's opening. Travelers, whose behaviors are to be analyzed, are divided into three groups, including drivers, BTS sky train, and public bus riders. The results of the before study show that the estimated values of station access time are 24.15, 24.14, and 21.81 percent of traveler's income, respectively. Comparisons of results from before and after studies reveal that the proportion of bus riders who stated that they would use the subway, but failed to do so, is significantly greater than that of BTS riders. Those proportions, however, are not significantly different in the case of drivers and bus riders. In addition, the proportion of overstatement does not depend on sex, age, or income groups. As for market share of the new subway, the predicted shares from the SP model are greater than the actual shares in all groups, the highest being 4.99 times overprediction for the group of drivers, followed by 2.98 times and 2.04 times for bus and BTS riders, respectively. This reflects that transportation planers should be careful when using SP models to predict modal shift for a new rail transit system, especially the behavioral shift of traveler, who currently drive or use public buses.