交通壅塞一直是大多數都市面臨的課題。交通壅塞不只會造成能源的消耗，也會為環境帶來汙染。在都市的尖峰時間，許多幹道都呈現過飽和的情況，過飽和的情況可能會造成車輛回堵到上游路口、左轉與直行車輛相互堵塞，或是因各轉向比間之差異，造成某車道之等候列隊長度較相鄰車道長，進而增加駕駛人變換車道的行為。且目前都市地區不易取得道路用地拓寬道路來降低過飽和之情況，因此透過調整時制計畫來增進路網效率，不失為一個快速、有效且省成本的方法。本研究目的為在考量過飽和車流情況下，建立一號誌最佳化模式，以期讓整體路網之效率達到最佳化。本研究最後將TRANSYT-7F 以及TRANSYT 14 與本模式求解出之最佳化號誌時制分別放入TSIS 模擬，結果發現本模式在近飽和或是過飽和狀態下，皆能有效降低平均每車延滯或是提高最大通過量。

Traffic jams are a big issue in most cities. The traffic jam causes energy waste and air pollution. Arterials in some urban areas are often oversaturated in peak hours. Oversaturated conditions include spillback, lane blockage, and unbalance queue which is caused by different turning ratio and will increase lane-changing behavior. However, land acquisition for road construction becomes more and more difficult. Retiming traffic signals is an efficient and low-cost way to reduce road congestion. This study proposes a model which optimizes signal timings under oversaturated conditions. The optimized signal timings from TRANSYT-7F, TRANSYT 14, and the proposed model input into TSIS for comparison. The result presents the proposed model reduces total delay or increases total throughput under oversaturated conditions as well as near-oversaturated conditions.