臺鐵時刻表穩定度與效率評估

Evaluation of Timetable Stability and Efficiency for Taiwan Railways Administration

李宗晏(Tsung-Yen Li)

指導教授 ： 賴勇成

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.2010.00346

摘要

可靠的軌道營運系統必須仰賴穩定的時刻表，較穩定的時刻表在軌道系統發生異常狀況時，能夠快速地排除受影響的列車，有效地使系統回復到正常營運狀態。營運列車數的多寡不僅影響時刻表穩定度，更反應出路線容量的使用效率，當營運列車數越多時，容量的使用效率較高，同時也造成殘餘容量較低，可能降低時刻表穩定度；反觀容量使用效率低時，剩餘容量較高，雖可能增加時刻表的穩定度，但效率太低時也可能造成容量上的浪費。因此時刻表穩定度與路線使用效率存在著取捨與權衡關係。
　　過去經常透過模擬方法和解析方法來評估軌道系統時刻表的穩定度，並以系統中斷時所造成的期望延滯作為衡量的指標。一般而言，延滯乃指實際到站時刻與表訂到站時刻的時間差距，並無考慮到軌道運用中隱含的殘餘容量。倘若使用延滯來評定時刻表穩定度，則會忽略了容量使用效率所帶來的影響。因此，本研究提出回復時間的觀念，來取代延滯時間的不足，並建立軌道容量運用效率與風險分析模式來評估時刻表穩定度與系統容量使用率。
　　軌道容量風險定義為系統中斷的發生頻率與造成的嚴重度之乘積。由於系統存在各種潛在的中斷情況，透過營運風險資料庫中所紀錄列車營運的歷史資料以及欲評估的時刻表來進行分析各種中斷情況的發生頻率。嚴重度分析的部分將考慮軌道容量的使用情況，以「回復時間法」來評估嚴重度。本研究中所提出的「回復時間法」之概念為列車因事故發生而造成中斷，在中斷時間內所無法運行之列車待事故修復後的剩餘容量來消耗，此過程稱為回復時間。相較於傳統的延滯時間計算方式，回復時間分析方法更可以清楚描述列車服務中斷的嚴重程度以及考量軌道容量使用效率的影響，並可消除列車延滯時間所帶來的不足。

關鍵字

時刻表穩定度 ； 軌道容量 ； 回復時間 ； 風險分析

並列摘要

Reliable railway operation is a result from a well-designed timetable; this timetable must be robust and stable under its own operational environment. Due to the potential system interruptions, a timetable should incorporate an appropriate level of slacks in order to efficiently recover the system to normal state. In general, the capacity concerns with the number of tracks, which is capable to provide more trains passing, once the operation of a rail track was interrupted, the number of operating trains at this time must be a key factor to influence the timetable stability. While the number of operating trains
is less in this time, which can provide more buffer time, which means the present timetable will perform with higher stability, otherwise not. In addition, there is a trade-off relationship between timetable stability and the usage of capacity, therefore, the number of operating trains not only influence the timetable stability but also reflect
the used efficiency of capacity.
　　Simulations and analytical methods have both been used to evaluate the stability of railway timetables. These types of methods compute the expected delay from a particular timetable with system disruptions. This delay can capture the difference between the real arrival time and the scheduled arrival time; however, this kind of
evaluation does not take into account the original slacks built-in the timetable. Therefore, a timetable with a surplus of slacks would have an excellent on time percentage but the inefficient usage of trackage would not be penalized. The more operating trains the lower the buffer time and timetable robustness; otherwise, the high
stability caused by relative less operating trains result in losing usage of capacity. Consequently, the new railway capacity risk analysis model was proposed considering
the network capacity usage to evaluate the timetable stability and the efficiency in thisstudy.
　　The railway capacity risk is defined as the product of the frequency of system disruptions and the consequence from the disruptions. Since there are a number of different types of system disruptions, the frequency of system disruptions will be computed via the railway operational risk database and timetable, and then determine the frequency of system disruptions.
　　The consequence analysis of each type of service interruptions will be analyzed by using “recovery time methodology” according to a particular level of capacity usage. For railway transportation, capacity is defined as the highest volume of traffic (e.g. trains per hour) that can be moved over a section of the network under a specified
schedule and operating plan while not exceeding a defined threshold. This capacity value for each section in the network can be determined based on its properties related
to operational and infrastructure characteristics. With the capacity defined, the model can then analyze how much slacks are there for each section of the network under a
particular timetable. In this study, the concept of recovery time methodology is the train interruption caused due to an accident occurred, then the number of trains in the interruption time will be from the accident was repaired and this process is called recovery time. This new recovery time analysis can clearly depict the consequence from service disruptions and also the efficiency of capacity usage. This process will help railway agencies provide reliable services to their customers, and return on shareholder investment.

並列關鍵字

timetable stability ； railway capacity ； recovery time ； risk analysis

參考文獻

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