台北大眾捷運後續路網替選方案之評估研究

Abstract

台灣目前大眾運輸相關審議機制中，並無嚴謹替選方案分析。檢視台北捷運第三階段路網之可行性研究中，固然闡明選擇軌道捷運系統之原因，然而台北捷運平均每公里44.07億元新台幣、路網邊際效益遞減，加上成本、運量以及施工時間的不確定性，採用施工期長、建設成本高之軌道捷運系統可能無法及時解決交通問題並達到預期的效益。因此，本研究針對台北捷運第三階段路網，研擬成本效益較佳的替選方案進行比較分析。研究中以台北捷運第三階段路網中的南北線與民生汐止線為對象，建設時考慮大眾捷運系統以及公車捷運系統，配合整體路網，以旅次總成本、燃油消耗量與二氧化碳排放量為評估指標，進行替選方案評估。本研究針對零方案、MRT及BRT替選方案，採用台北都會區整體運輸規劃模式(DOST I)建構替選方案未來年期之大眾運輸路網，其中BRT方案之大眾運輸路網較MRT方案提早7年完成。模式建構時將BRT與MRT系統之差異反映在票價、營運速率、設站距離及服務班距，同時BRT系統採用平面公車專用道，因此行經之路線單向皆縮減一個車道，原先為單向一車道之路段則採混合車流方式，以較低之營運速率進行分析。根據運量預測之結果，BRT替選方案於2031年之大眾運輸使用率最高(47.29%)，私人機動運具使用率最低(44.8%)。替選方案中捷運路網通車之年期，公車使用比例皆受到最大之衝擊，而BRT行經路線車道縮減，對私人機動運具旅次產生明顯之移轉效果。此外，BRT替選方案具有旅次總成本降低以及節能減碳之優勢，分析結果顯示2031年 BRT相較於其他方案之旅次總成本年效益為106億，而每年節省15,581公秉油耗量，減少59,037噸二氧化碳排放量，為MRT替選方案效益之3.8倍。但由於小汽車之油耗量遠大於其他運輸工具，在未實施較為強制的私人機動車輛管理措施下，各替選方案之油耗及二氧化碳排放量之成長趨勢，並未隨大眾運輸路網增加而趨緩。

In review of public transit development project, there is a lack of appropriate alternatives analysis in Taiwan. In the feasibility studies of Taipei Metro future network, the reason of constructing MRT is only described briefly. However, average cost of Taipei Metro network is 4.4 billion per kilometer and the marginal benefit is decreasing, while the uncertainty of cost, ridership, period of construction, and the expected benefit of MRT system may not be reached. Therefore, this research aims at the alternatives analysis on future network of Taipei Metro. In the alternatives analysis, Eastern Taipei North-South Line and Minshen-Xizhi Line are identified as priority corridor, and therefore 3 alternatives are proposed, namely, DO NOTHING, MRT and BRT. Full trip cost, fuel consumption, CO2 emission are considered as the performance indicators in evaluation while future public transit network is developed with DOTS I model. It is shown that BRT network is finished 7 years earlier than the original MRT alternative. Differences between MRT and BRT have beem reflected on price, operating speed, stop spacing and headway in the model. At-grade bus lane is adopted for BRT system; therefore, one lane is deducted where BRT routes pass through. It is shown from the ridership forecast that bus suffered from obvious ridership decreasing in all alternatives and lane-deduction has signigicant impact on private mode. BRT alternative has the highest public transit usage (47.29%), lowest private mode usage (44.8%) in 2031, and also has advantage on all other indicators. The results have also identified that, BRT alternative saves 15,581 kl of fuel, reduces 59.037 tons of CO2 and gains the benefits from full trip cost of 10.6 billion per year. Because the amount of fuel consumed by private vehicles is still much higher in various alternatives, the growing trend of alternatives’ fuel-consumption and CO2-emission do not really reduced without sincere restriction on private vehicle.