雙車道公路單向只有一車道讓小車及大車行駛，超車必須占用對向車 道之公路。臺灣郊區雙車道公路又受地形影響，常有陡坡及曲率半徑小的 平曲線，造成車流運作狀況複雜。由於雙車道公路現場車流特性資料蒐集 困難，且即使有龐大的資料也不容易建立可靠的分析性方法，因此許多國 家發展模擬模式，以分析雙車道公路及其他有坡度路段公路之運作績效， 作為公路規劃、設計及改善方案評估之工具。交通部運輸研究所(以下簡稱 運研所)開發之2016 年公路交通系統模擬模式（2016 Highway Traffic System Simulation Model，簡稱2016 HTSS 模式），可以合理模擬臺灣郊區雙車道 公路非阻斷性之平坦及坡度路段的車流。本研究先以本土車流調查結果， 提出雙車道公路平直路段流率與速率之可能關係，並測試及微調模式。而 於雙車道公路特有之對向超車行為，則參考國外研究，建構2016 HTSS 模 式之超車行為。再以本土資料微調模式，以探討適用於臺灣郊區雙車道公 路坡度路段設計之代表性車輛；最後說明模式於坡度路段容量分析及幾何 設計之應用。

Two-lane highways have only one lane in each direction capable of accommodating passenger cars and large vehicles. Passing vehicles on such highways have to utilize opposing lanes. Because of rough terrains, the rural two-lane highways in Taiwan often have steep grades and sharp horizontal curves and thus have complex traffic operating characteristics. Even if a large amount of field data is available, it is difficult to develop reliable analytical tools for analyzing this type of highways. Consequently, many countries have resorted to the development and use of simulation models to facilitate planning, design, and assessment of improvement strategies. The 2016 Highway Traffic Systems Simulation (2016HTSS) model developed by the Institute of Transportation (IOT), Ministry of Transportation and Communications, can reasonably simulate the traffic operations of Taiwan’s rural two-lane highways. This paper presents the likely speed-flow relationships on straight and level segments of Taiwan’s rural highways, discusses the nature of passing behavior and its simulation, explores the representative vehicles suitable for design and analysis of the grade segments on Taiwan’s rural two-lane highways, and illustrates the applications of the 2016HTSS model.