高速公路長途客運車輛最佳座位數之研究

A Study on Optimization of the Number of Seats for Intercity Bus

國道客運路線之客車以雙排總統座椅提供運輸服務已漸蔚為風潮，本研究旨在從客運服務品質與資源有效運用的觀點探討此種減少供給能量之服務方式之適宜性。所構建之分析模式係以管制者觀點尋求社會總成本最小之班車座位數，最佳座位數與等車時間價值、等車時間對班距比值及合理乘載率成反比；與最大設計承載量、各時段需求平均、總行駛時間等變數的平方根成正比。本研究並以台北--台中線之需求進行實證分析，受到需求與總行駛時間變異影響，業者之供給多有不足的現象，乘客平均等車時間與班距之比值多大於2，以目前之需求水準而言，33座或45座應為較適宜國道客運營運之座位數而非19座之總統座椅。

Recently, intercity bus companies has adopted an innovative 'Presidential Seating' configuration (19-21 seats per standard bus) to provide long haul service in Taiwan. The purpose of this study is to discuss the suitability of this kind of service in view of bus service quality and resource allocation. An analytical model is developed to find the optimal number of seats that minimizes the total social cost. The model considers not only operators' cost and users' cost but also freeway congestion cost due to a more frequent schedule. Based on the assumptions that the number of buses is unlimited, the demand of passengers will not vary with different types of seating, and passengers arrive uniformly within each period, the optimum number of seats is directly proportional to the square root of the passenger demand, the bus turnaround time and the bus operating cost, and is inversely proportional to the waiting time value, the ratio of waiting time to headway, and the load factor. A demand survey of the Taipei-Taichung Line was conducted in order to proceed an empirical study. The results show that the intercity bus service is seriously short of capacity because of the variation of demand and turnaround time. The ratio of waiting time to headway is larger than 2. According to the existing passenger demand of Taipei-Taichung Line, 33 or 45 seats per bus is more suitable and efficient for intercity bus service, while not the so-called 'Presidential Seating' with only 19 seats per bus.