輕軌優先號誌策略選擇流程之研究

Abstract

為了提升輕軌運輸系統之運行效率，許多研究提出使用輕軌優先號誌策略， 當輕軌於路口與公路交流時優先給予輕軌可通行時相，而使用優先號誌可能對衝 突向車流帶來龐大的衝擊，了解不同路口變數會如何影響使用優先號誌後的公路 延滯及輕軌延滯成為重要的課題。本研究建立一套離散模擬計算輕軌經過三種優 先號誌策略：絕對優先、相對優先、不優先，各路口號誌時相的改變及輕軌時空 位置，並以車流模擬軟體 SUMO 建立路口，改變路口參數數值收集模擬資料，接 著以收集的模擬資料分析不同路口變數對使用不同優先號誌策略績效的影響，以 提出一套評估路口輕軌優先號誌選擇之流程，並且以淡海輕軌一期路網作為模擬 驗證及優先號誌選擇流程應用之對象，提出輕軌優先號誌設置之結論與建議。

本研究結果發現衝突向飽和度對使用優先號誌下的公路延滯時間有較大的影 響，當衝突向飽和度大於 0.8 時，不建議使用優先號誌；路口號誌時相數則是以 簡單二時相對使用優先號誌的影響不大，當時相數為三時相時，路口延滯則整體 上升，此時使用優先號誌下的路口延滯更容易受到其他變數的影響而上升；路口 號誌週期長度越短，在衝突向飽和度較高的情況下使用優先號誌，容易使路口延 滯大幅度上升，因此欲在衝突向飽和度較大的路口使用優先號誌，可採較長之號 誌週期長度。

To enhance the operational efficiency of the light rail transit system, many studies have proposed the use of transit signal priority strategies. These strategies prioritize the light rail vehicles at intersections, granting them the right of way during certain signal phases. However, implementing transit signal priority may lead to significant impacts on cross-street traffic. Understanding how different variables at intersections can affect highway delay time and light rail delay time after implementing transit signal priority has become an important issue.

This study established a discrete simulation to obtain the changes in signal phases at intersections with three transit signal priority strategies: unconditional priority, conditional priority, and no priority. Then, the traffic simulation software SUMO was used to simulate the traffic conditions under different intersection parameters. The collected simulation data was then analyzed to examine the influence of different intersection variables on the performance of different signal priority strategies. This study aims to propose an evaluation process for selecting light rail priority signal settings at intersections. This study applied the proposed evaluation process to the Danshui light rail network for simulation validation and providing conclusions and recommendations for light rail signal priority implementation.

The research findings indicated that volume-to-capacity ratio of cross-street traffic has a significant impact on traffic delay under the use of signal priority. When the volume-tocapacity ratio exceeds 0.8, it is not recommended to use signal priority. The number of signal phases at intersections also has effect on the use of signal priority. Less number of signal phases could reduce the traffic delay when the signal priority is used. Using transit signal priority under a shorter signal cycle length at intersections can lead to a substantial increase in delay, particularly in situations with higher volume-to-capacity ratio. Therefore, to use the signal priority a longer signal cycle length is recommended at intersections under higher volume-to-capacity ratio of cross-street traffic.