TGS-2L模式於郊區雙車道公路坡度路段之應用

APPLICATIONS OF TGS-2L MODEL ON GRADE SEGMENTS OF SUBURBAN AND RURAL TWO-LANE HIGHWAYS

目前國內對於郊區雙車道公路交通特性的了解相當有限，尤其是有平曲線及坡度的郊區雙車道公路，其坡度路段的車流特性與平坦路段具有很大差異。有鑑於容量及服務水準分析之需要，交通部運輸研究所發展之公路坡度路段模擬模式(Traffic-on-Grade Simulation Model，簡稱TGS-2L模式)已經可以分析臺灣郊區雙車道公路之車流特性與交通運作。本研究主要探討如何利用TGS-2L模式模擬郊區雙車道公路之運作，並進一步分析其坡度路段之車流特性。模擬分析主要成果包括：上坡及下坡路段之自由車流速率隨著坡度及坡長的變化、上坡路段速率隨對向流率及坡度的變化、常見均勻坡度的路段容量等。最後，本研究說明如何利用TGS-2L模式分析郊區雙車道公路之服務水準，並以北宜公路(臺9線)為對象進行模擬分析發現，北宜公路單向容量約1,355~1,360小客車／小時，北向若再增加400小客車／小時，其服務水準還可接受，故可作為分散部分國道5號北上車流之一改善措施。

The characteristics of traffic flow on suburban and rural two-lane highway, especially on upgrade and curve segments, are lack of understanding in Taiwan. The traffic flow characteristics on grade-segments of suburban and rural two-lane highway are significantly different from those on level segments. Institute of Transportation developed the Traffic-on-Grade Simulation (TGS-2L) model to support highway capacity analysis. This study applied the TGS-2L model to simulate the traffic condition on suburban and rural two-lane highways. Based on the results of the simulation, this study found that the variety of free-flow speed with various grade and length of grade, the variety of speed with grade and opposite flow rate, the capacity of uniform grade sections, etc. Finally, this study presented how to use TGS-2L model to find the level-of-service of suburban and rural two-lane highway. Moreover, a case study of Pei-Yi highway (Tai No. 9 highway) found the capacity are about 1,355~1,360 passenger car/hr each direction. The level-of-service could be acceptable when the volume increases 400 passenger car/ hr on northbound. That could be one of the countermeasures for dispersing northbound traffic of No. 5 freeway.