西濱快速公路容量與服務水準分析方法之研究

Abstract

由於國內對於快速公路車流特性與容量之研究非常有限，「二○○一年台灣地區公路容量手冊」中仍缺乏城際快速公路容量與服務水準之分析，因此本研究乃利用交通部運輸研究所2001年所調查之基本資料，以比較嚴謹的方法對西濱快速公路交通特性及容量分析方法作深入研究。主要研究內容與方法如下： 1.由相關文獻回顧對流率時段變動之影響分析，決定適當的樣本時段，作為基本路段容量推估之取樣時段。 2.利用車流特性調查資料，建立路段長度與自由車流速率之關係式，找出不受路口號誌影響之基本路段長度。 3.應用車流理論之流率－速率－密度關係，構建平直暨坡度路段之車流模式，並以統計方法檢定最佳模式，作為推估路段容量與界定服務水準等級之依據。 4.選擇密度為基本路段之主要服務水準評估指標，服務水準等級之界定係參考台灣地區及美國高速公路基本路段暨多車道郊區公路服務水準劃分標準。 5.建立非基本路段平均旅行速率模式，並參考台灣地區暨美國公路容量手冊中之都市幹道服務水準劃分之標準，界定西濱快速公路非基本路段服務水準之等級。 本研究所獲致之主要結論如下： 1.依據路段長度與自由車流速率之關係，界定基本路段長度為2.5公里以上。 2.平直路段構建之車流模式以Greenshield’s線性模式為佳；而坡度路段則以Underwood所構建之指數車流模式較佳，分別據以推估容量，得平直路段容量平均為1950pc/hr/ln；上坡路段（坡度4.49%，坡長0.5公里）容量平均為750pc/hr/ln，可知坡度與坡長對路段容量有顯著的影響。 3.平直基本路段之臨界密度發生在61pc/km/ln，明顯高於台灣2001年公路容量手冊中高速公路基本路段臨界密度值（35pc/km/ln）暨多車道公路之臨界密度值（52.5pc/km/ln），此乃因所調查樣本之速率普遍偏低，造成臨界密度值偏高。 4.評估非基本路段服務水準之主要指標為平均旅行速率，係整合區段之平均行駛時間與延滯時間而得，其影響因素計路段長度、需求流率與延滯時間等，本研究分別探討各影響參數之變動對平均旅行速率之影響，得到不同長度於不同流率變動情形下之平均旅行速率。並參考都市幹道服務水準等級劃分之標準，訂定西濱快速公路非基本路段服務水準等級。因此由不同之路段長度、需求流率求出區段平均旅行速率，即可界定其服務水準等級。

Due to very limited study of the traffic flow characteristic and capacity on expressway in Taiwan , this study has used the raw data that is surveyed by IOT of MOTC to analyze the traffic & characterists to establish an appropriate set of procedures for analyzing the capacity and level of service of Hsi Pin Expressway on basic and non-basic segment . The main contents and approaches used are as follow： 1.To determine appropriate sampling time interval of surveyed data , serving as the basis of capacity analysis of basic segment. 2.To establish the relationship between segment length and free flow speed , find out the length of basic segment not been influenced by signalized intersection . 3.To develop appropriate traffic flow models for the basic segment , which are used to evaluate the capacity and define the level of service. 4.Choosing density as the primary MOE to define level of service of basic segment , by making reference to the method of the freeway basic segment and multi-lanes highways in Taiwan and U.S.A. . 5.To establish the level of service evaluation procedures and methods that fit Hsi Pin Expressway traffic flow characteristic on non-basic segment . The main conclusions drawn from this study are ： 1.According to the relationship between the segment length and the free flow speed , the minimum length of the basic segment is defined as 2.5 km . 2.The traffic flow models developed for the level and grade segment is that the Greenshield’s linear model is better for the level segment ; and the Underwood’s exponential model is better for the grade segment . The capacity is about 1950 pcphpl for the level segment , and about 750 pcphpl for the grade segment. 3.The critical density measured from the model is about 61 pc/km/ln for the basic segment , which is different form the freeway basic segment and the multi-lanes highways , that is mainly due to the fact that the raw free flow speed data collected by the IOT is generally too low and result in the critical density is too high . 4.Travel speed is used as the primary MOE of level of service for the non-basic segment . Procedures to predict travel speed , and to define the level of service for the non-basic segment of Hsi Pin Expressway are developed , making reference to the Urban Arterial of 2000 HCM in U.S.A. .