本研究假設在兩車道下,設定三種汽機車車道劃設方式:(一)專用道,汽車僅能行駛左側車道,機車僅能行駛右側車道;(二)部分專用道,汽車可行駛左側與右側車道,機車僅能行駛右側車道,與汽車形成混合車流;(三)混合車道,汽車與機車皆可行駛於兩車道,兩車道皆為混合車流。藉由計算整體使用者均衡與社會最適化兩種情況,以了解在何種情境可得最大之社會淨效益,並使用台北-板橋運輸走廊之旅次資料進行案例分析,最後並進行敏感度分析。 整體而言,在使用者均衡時,情境三之社會淨效益最大、汽車淨效益於情境二最大而機車淨效益於情境一最大;於社會最適化時,情境一之社會淨效益與機車淨效益皆最大,汽車淨效益則於情境三最大。 各情境由使用者均衡改為社會最適化均可增加社會淨效益,由案例分析得情境一可增加21%、情境二可增加17%而情境三可增加15%之社會淨效益,故專用道並課徵外部性稅時之社會最適情況增加之總淨效益最多。
This study analyzes the problem of lane designation for a road with two lanes, virtual left sub-lane (VLSL) and virtual right sub-lane (VRSL). Three scenarios are assumed for the lane designation including segregation lanes (SL), partial segregation lanes (PSL) and integration lanes (IL). SL allows automobile users to use VLSL and motorcycle users to use VRSL. PSL allows automobile users to use both VLSL and VRSL, and motorcycle users use VRSL only. IL allows both automobile users and motorcycle users to use both lanes and this makes mixed traffic on the road. Analyzing the total social net benefit in the case of user equilibrium situation and social optimum situation provides the understanding of which scenario yielding the larger total social net benefit. The model is then applied to the case of the transportation corridor between Banqiao and Taipei CBD. Sensitivity analyses are also made for the changes in the value of parameters. In the user equilibrium condition, IL yields the largest total social net benefit, PSL yields the largest automobile user net benefit, and SL yields the largest motorcycle user net benefit. On the other hand, in the social optimum condition, SL yields the largest total net benefit and the largest motorcycle user net benefit, while IL yields the greatest automobile user net benefit. Comparing with the case of user equilibrium, the social optimum case can yield a higher total social net benefit in each scenario. An increase of 21%, 17% and 15% in total social net benefit is obtained in SL scenario, PSL scenario and IL scenario, respectively. The scenario of segregation lanes can thus yield the largest social net benefit in the social optimal condition by levying an external tax on the road users.