右轉車輛與行人同一時相對混合直右車道飽和流率之影響分析與改善策略評估

Abstract

臺灣交叉路口之號誌設計多讓右轉車輛與行人共用時相，因此右轉車輛須於人群之間尋找縫隙以穿越行人。近年來，政府訂定了禮讓行人計畫，並透過警方交通執法，加強取締不暫停禮讓行人先行通過之車輛，使得民眾逐漸建立此習慣。然而於尖峰時段，車流量與行人量較大，當車輛右轉停等禮讓行人時，可能造成混合直右車道之疏解率下降，因此本研究考量臺灣混合車流之交通情況，探討影響混合直右車道飽和流率之因素，並針對顯著之影響因素研擬改善策略。 首先蒐集台北市市區幹道之純汽車車流飽和流率及混合車流飽和流率，利用飽和容量法，採取容量固定之迴歸方式以得於不同混合比下機車之小客車當量值，並使用此當量值計算所蒐集到之台北市市區幹道混合直右車道之飽和流率。本研究以每一週期作為一樣本，利用皮爾森相關分析得出顯著影響飽和流率之因子，隨後將影響因子設為自變數，飽和流率設為應變數，以逐步迴歸法進行多元線性迴歸分析，得混合直右車道飽和流率推估模式，模式中自變數包含汽機車右轉比例和汽機車與行人衝突比例。 本研究針對汽機車與行人衝突比例進行改善策略研擬，以行人綠燈早關作為人車衝突之改善方案，參考和平東路–新生南路交叉口中和平東路往西之幾何設計及號誌設計，利用VISSIM微觀車流模擬軟體，以平均延滯時間作為績效指標，評估不同右轉交通量應搭配之最佳之行人綠燈時間，作為未來交叉口績效改善之參考。

The typical traffic signal design at signalized intersections in Taiwan usually allows right-turn vehicles to share the same phase with pedestrians. Therefore, right-turn vehicles must find a gap between pedestrians to make right turns. In recent years, the Government has encouraged drivers to yield to pedestrians, and enforced new laws banning vehicles that do not give way to pedestrians, which has led to the gradual establishment of this habit by the public. However, during peak hours, the traffic volume and pedestrian volume are relatively high. Right-turn vehicles waiting for pedestrians at crosswalks may cause the discharge flow rate of shared right-turn lanes to decrease. The study considers heterogeneous traffic condition in Taiwan, aiming to derive the influence factors on shared right-turn lanes and proposing some improvement strategies. The study collects the saturation flow rate of straight lanes without motorcycles and straight lanes with heterogeneous traffic flow on the arterial roads in Taipei City, adopting a fixed-capacity regression method to determine the passenger car equivalent (PCE) value of a motorcycle for different motorcycle mixture ratios. The PCE value is then used to calculate the saturation flow rate of heterogeneous shared right-turn lanes in Taipei City. In this study, each cycle is used as a sample. Pearson correlation analysis is adopted to derive the factors that significantly influence the saturation flow rate. After that, the influence factors are set as independent variables while the saturation flow rate is set as the dependent variable. Multiple linear regression analysis is conducted to obtain the saturation flow rate estimation model of heterogeneous shared right-turn lanes, with right-turn proportion and right-turn vehicle-pedestrian conflict proportion acting as two major influence factors. To reduce right-turn vehicle-pedestrian conflict proportion so as to increase the saturation flow rate of heterogeneous shared right-turn lanes, the study proposes the pedestrian early-stop signal phase as an improvement strategy. The geometric design and signal design of Heping East Road – Xinsheng South Road intersection are taken as a case study. VISSIM, a microscopic traffic simulation software, is used to evaluate the performance of different pedestrian green time and different right-turn traffic volume, with the average delay time as the performance indicator. The result shows the best pedestrian green time under different circumstances, and is expected to be a reference for intersection performance improvement in the future.