高速公路瓶頸路段車流模式之研究

Abstract

在正常車流狀態運行下，高速公路能提供用路人快速、便捷的高水準服務 ；然而一旦發生交通事故或進行道路的養護施工時，常必須封閉部份車道 ，造成道路容量的降低，因而影響到正常的車流，使得該路段造成擁擠、 旅行時間的增長及其他財物損失。若能即時將此類擁擠區域、路段或旅行 時間等路況資訊提供予管理者研擬交通管制計畫，或提供予用路人以誘導 其改道行駛，應可減低該路段對車流的干擾及降低該路段的交通擁擠。瓶 頸路段車流特性的分析乃是對瓶頸路段進行交通管制計畫的基本工作；故 本研之目的在建構高速公路瓶頸路段的車流行為模式，以作為將來分析瓶 頸路段對上游車流延滯情形的基礎。本研究首先考慮高速公路上一均質、 無進出口匝道的二車道路段，其中有一車道的部份路段封閉，觀察未封閉 車道的車流行為，以流量守恆律為基礎，構建該瓶頸路段的車流行為模式 ，再以特徵曲線法求解模式得車波軌跡函數及密度函數，並以數值模擬方 法模擬二車道瓶頸路段車流模式，所得結果與預期路況密度相近。接著， 探討多車道瓶頸路段的車流行為，並分別以流量守恆律、構建多車道瓶頸 路段一階車流模式及高階車流模式。 Freeways provide exclusively for through movement of traffic at high speed under normal situation. However, whether the bottlenecks are caused by incidents or roadwork, may reduce the capacity of freeway and generate traffic congestion. Soon after an incident happened, if the speed information for the bottleneck could be given to the upstream drivers immediately, which can reduce the emission and fuel consumption, in addition to lowering traffic congestion and travel cost. An analytical procedure to study the effect of freeway bottlenecks is the need for effective traffic control of the road section under construction which is one of the major tasks in the process of freeway construction and maintenance. The purpose of this research is to construct a traffic flow model to describe the characteristics of traffic flow at bottlenecks. In this study, a special case of an uniform two-lane freeway with no entrances or exists, and with bottlenecks is discussed. The mathematical model of the traffic flow describing the dynamic evolution of traffic variables along the normal lane are developed by conservation law and the momentum equation. The models are solved by characteristic method and simulated by adaptive finite difference method. Then, the multilane freeway bottleneck models are extended. Finally, the existence and uniqueness properties of the solutions are also discussed.