高速公路連鎖式匝道儀控模式之研究

Coordinated Freeway Ramp Metering Control Model

鄭鎧鋙(Kai-Yu Cheng)

指導教授 ： 許添本

國立臺灣大學/工學院/土木工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.03171

摘要

高速公路每逢連續假期即會湧入大量車潮，需求流量超過高速公路之容量而導致壅塞發生。匝道儀控是高速公路交通壅塞管理的主要方法之一，能調節主線車流量，避免主線發生過飽和之情形；目前在高速公路實施之匝道儀控，主要為定時儀控，僅考慮單一匝道來制訂儀控策略，此控制方式無法即時地反應實際車流變化，且單一匝道之車流量過高時，導致主線等候車隊長度向上游延伸，此時需調整上游匝道之儀控率，避免使壅塞情形更為嚴重。因此本研究考慮高速公路整體績效，以線性之最佳化控制之方式來建立連鎖式匝道儀控模式，並採用交通感應儀控之作業方式，即時地計算各控制時段之最佳儀控率。
本研究之最佳化模型以車流模式為基礎來建立最佳化模型，車流模式採用中觀車流模式中之修改後的格位傳送模式(Modified Cell Transmission Model, MCTM)，其具有簡易計算本質，僅需要建立其模式基本規範，即可作為動態即時應用。研究架構主要分為兩大步驟:第一步驟為校估車流模式所需參數，並進行模式驗證；第二步驟為建立最佳化模型，計算最佳儀控率，進而評估其績效。
本研究蒐集國道五號於2009年端午節連續假期之偵測器資料，並以國道五號宜蘭端北上路段作為控制範圍，依偵測器資料來校估MCTM所需參數，並採用MAPE作為評估指標來進行模式驗證，結果顯示本研究校估之參數使MCTM能夠合理地描述車流變化之情形。
本研究假設兩種情境來求解最佳儀控率:第一種情境為不考慮匝道等候長度限制，第二種情境為考慮匝道等候長度限制，並以總花費時間(Total Time Spent, TTS)、總旅行時間(Total Travel Time, TTT)及總等候時間(Total Waiting Time, TWT)來評估各情境之績效。研究結果發現不管在何種情境下，本研究所構建之最佳化模型皆能改善國道五號於連續假期之壅塞程度，然而情境一使得頭城上匝道之等候車隊回堵過長，因此本研究以情境二為兩者中較佳之方案。

關鍵字

匝道儀控 ； 交通感應儀控 ； 最佳化控制 ； 車流模式 ； 格位傳送模式

並列摘要

The freeway always occurrs critical congestion on vacations in Taiwan, and ramp metering control is one of the ways to solve the congestion problem of freeway. All ramp metering on freeway at present are controlled isolated and the metering adopted fixed time class which can not detected real-time flow of mainline and ramp, and it will lead the queue of mainline back up onto upstream when a ramp with excess demand; at this time, it must adjust the metering rates of ramps at upstream, so in this research, the network was considered, and the coordinated ramp metering control model which formulated as linear optimal control model and the metering rate executed with traffic-responsive control was proposed.
This optimal control model was formulated by using modified cell transmission model (MCTM), it easily to calculate, and it can apply to dynamic control with the basic rules of MCTM. The framework of this research divided into two steps. The first step was to calibrate the MCTM parameters, and to ensure MCTM can replicate the freeway traffic behaviors; the second step was to calculate the optimal metering rates, and then evaluate its performances.
In this research, the optimal model was tested numerically using data from a severely congested stretch of freeway at National Freeway No.5 during 2009/5/28 to 2009/5/31, and it were also used to calibrate MCTM parameters. Then, the Mean Absolute Percentage Error (MAPE) was selected as evaluation index, and the results showed that the MAPE of the MCTM falls into a reasonable range.
There are two conditions when the metering was calculated, the first one is the optimal control model without the consideration of the onramp queue length constrain, and the second one is the optimal control model which consider the onramp queue length constrain. In addition, total time spent (TTS), total travel time (TTT) and total waiting time (TWT) were used to evaluation performances of the two conditions. The results showed that the proposed model can improve the congestion problems of National Freeway No.5 in both situations. However, the first condition causes long queue length at Toucheng onramp, thus the second condition is regarded as the better strategy.

並列關鍵字

Ramp Metering Control ； Traffic-Responsive Control ； Optimal Control ； Traffic Flow Model ； Cell Transmission Model

參考文獻

4. 卓訓榮、傅昱瑄、陳豐榮(2008)，「車流動力學模式」，運輸計劃季刊，第三十七卷，第一期，頁109-138。

7. 林豐博、蘇振維(2009)，「國道5號雪山隧道車流特性之研究」，運輸計劃季刊，第三十八卷，第一期，頁85-120。

11. 張堂賢、莊國欽(2004)，「非線性系統於高快速道路整合匝道儀控之研究」，運輸計劃季刊，第三十三卷，第四期，頁673-698。

13. 許添本(1994)，民國83 年，「多車種組合式模組化車流模擬模型之研究」， 行政院國科會專題研究計畫成果報告。

14. 許添本、簡正銓(2001)，「匝道儀控密度穩定法之研發」，運輸計劃季刊，第三十卷，第二期，頁275-302。