earticle

영어

In this study, an economic model of an urban transport system is developed to estimate the optimal bus service level considering substitution effects between car and bus. In textbook case, the service level of bus, i.e., frequency or mileage, at the first-best optimum should be set so that the marginal cost per unit bus-km is equal to the difference between the time savings generated by the marginal bus-km, and the delay due to the increase in bus mileage. However, in general, it is believed that the road congestion effect by increased bus mileage is relatively small compare with that of other road transport modes, such as private cars and trucks. Therefore, the road congestion effects are usually considered to be negligible in the analyses. On the other hand, the service level of bus considering substitution effects between car and bus should be set so that the cost of marginal bus service is equal to the difference between the time savings by the marginal bus and the total congestion effects upon road traffic due to the increase in bus mileage, i.e., upon car traffic plus upon bus traffic by itself at the first-best optimum. Hence, when the government wants to improve the service level of bus by increasing the frequency or the mileage of the bus, the trade-offs between waiting time savings of bus users and the increase in road traffic congestion should be carefully measured beforehand.