Travel Time Estimation Based on Greenshield's Model for Freeway Inter-Vehicle Communications

[[abstract]]在所有的交通信息，駕駛主要關注的是旅行時間。信息如車速和車流量都可從旅遊時間推導得到。本論文提出的演算法是基於從高速公路環路車輛偵測器收集的數據，和在高速公路不同出口之間的Greenshield’s模型供旅行時間預測。在Greenshield’s模型速度-密度之間的關係的自由流速度是用於旅行時間預測的一個重要參數。高速公路不同路段會有不同的Greenshield’s模型。在每個路段駕駛將會選擇一個適當模型參數進行估測計算作為參考和更新估計旅行時間以達到即時更新功能。 本論文提出一種即時旅行時間估計演算法。首先，在每路段環路車輛偵測器數據被收集作為旅行時間估算的參考信息。車間通信是透過使用DSRC和VANETs來實現。其次，從環路車輛偵測器數據被應用在Greenshield’s模型建立速度-密度與自由速度之間的關係。車載通信將這些數據傳送到交通管理中心數據庫進一步應用。最後，考慮到來自環路車輛偵測器數據和Greenshield’s模型和應用一個適當的權重因數進行的旅行時間估算。我們開發了的一個即時平均演算法。我們的模擬結果顯示，基於即時算法所發展的Greenshield’s模型是有效的，可供在高速公路上進行準確的旅行時間估算。[[abstract]]In all traffic information the main concern for drivers is the travel time Information such as vehicle speed and traffic flow are all should be derived from the travel time For predicting travel time this paper proposed an algorithm based on the data collected from the loop vehicle detector on freeway and the Greenshield’s model between different exits in freeway The relationship between speed-density free-flow velocity in the Greenshield’s model is utilized as an important parameter for travel time prediction Different freeway sections have different Greenshield's models The driver on each section will select a proper model parameter as the reference for performing the estimation algorithm and updating the estimated travel time achieve real-time update feature In this thesis a real-time algorithm for travel time estimation is proposed First vehicle loop detector data are collected in each section as reference information for travel time estimation Inter-Vehicle Communication is attained by the use of DSRC and VANETs Second the data from loop vehicle detectors are applied on the Greenshield's model to establish the relationship between speed density and free velocity These data are transmitted to the database in the traffic management center for further applications in vehicle-vehicle communications Finally a moving average algorithm is developed by taking into account the data from the loop vehicle detector and the Greenshield's model and applying a proper weighting factor for performing the travel time estimation Our simulation results show that the developed Greenshield’s model based real-time algorithm is effective and accurate for the travel time estimation on the freewa