T字型路口機車兩段式左轉待轉區之研究

Abstract

機車是一種成本低廉、機動性高、停車方便之運具，過去數十年之發展，機車已經成為國人的主要運輸工具之一。機車在道路交通安全方面，與汽車相比是一種絕對弱勢，每當有交通肇事發生，機車騎士之傷亡程度均較為嚴重。因此，在機車密度高的台灣，機車的交通安全應該受到更多的關注與重視。 機車於同向三車道以上之路口必須以兩段式進行左轉，該規定已經施行多年，而且獲得很好的成效。一般十字型路口可以將機車左轉待轉區退縮至路緣線內，而T字型路口之左轉待轉區因為受到路口條件限制而無法退縮，因此T字型路口之機車左轉待轉區即位於同向直行車道上，於是待轉之機車就與外側車道直行車流形成衝突，如此不僅危害用路人的安全，對於行經路口之車輛速率亦有負面影響。為探討此問題之嚴重性，本研究乃從「安全」與「速率」兩方面進行分析；同時為了改善T字型路口機車左轉待轉之問題，本研究特別以台北市多處T字型路口為研究對象，依據T字型路口之客觀條件，提出不同的改善對策，並建立T字型路口設置機車兩段式左轉待轉區之作業流程。 本研究以實際數據證明T字型路口機車兩段式左轉待轉區所造成的問題，並提出具體改善方法，若政府落實執行，應可提供機車使用者更安全的行車環境。

Almost all motorcycles in Taiwan are less than 250cc in engine displacement. They are small-size motorcycles. Since their operational characteristics are quite different from automobiles, motorcycles are not operated and treated as passenger-cars in traffic management in Taiwan. For example, for urban streets with three traffic lanes or more, motorcycles are not allowed to travel along the left side of the street and neither to make direct left-turn from the farthest left lane. They have to make indirect left-turns by crossing street twice separately. In order to facilitate the above- mentioned indirect left-turns, waiting zones are designated for motorcycles at some intersections. For four-approach intersections, designated waiting zones can be installed behind the curb line. However, it is rarely possible to find enough space for motorcycle waiting zone at T-intersections. Therefore, some motorcycle waiting zones are located in the way of through traffic and cause traffic conflicts. The objective of this study is to examine problems resulted from improperly installed waiting zones for indirect left-turning motorcycles at T-intersections. Safety and speed are adopted to reflect negative impacts of motorcycle waiting zones. Factors such as sidewalk width, parking regulation, number of left-turning motorcycles, and distance to next intersection are taken into consideration for developing feasible alternatives. Finally, an operational process for improving waiting zone for left-turning motorcycles at T-intersections is proposed.