鐵公路轉運站公車適時派車決策模式之研究

Abstract

本研究係針對鐵、公路的適時化轉運模式進行研究。通常在轉運站中，將各不同路線車輛的班表加以整合，可以減少旅客在轉運站所花費的候車時間。但由於車輛到站的時間具有變異性，因此可在車輛的班表中加入寬容時間，藉此提高轉運旅客成功轉運的機率，然而於班表中加入寬容時間也會造成車輛運轉成本的增加，因此必須系統化的考量。 過去已有文獻構建多條公車路線間轉運之適時轉運模式，但鐵、公路基本運行特性不同，在構建鐵、公路適時轉運模式時所需考量的因素也有所不同。本研究構建之模式考量的成本函數，包括非轉運成本及轉運成本，非轉運成本包含(1)車輛運轉成本;(2)旅客候車成本;(3)旅客旅行時間成本。在轉運成本部分，則包含受寬容時間影響的各項轉運成本及延遲公車發車所造成的成本，例如延長公車發車班距後，所需採取補償策略（如號誌路口公車優先通行）所衍生的成本。 通常火車行駛於特定的路線上，不受其它交通狀況的影響而有較高的準點性，同時其載客量及營運成本皆較公車高，因此較不適合在火車班表中設計寬容時間。此外，當火車遲到時，本研究也採用延遲公車發車的方式來增加火車旅客轉運成功的機率，但延遲公車派車會造成公車營運成本及非轉運旅客等候時間的增加，且若延遲公車發車後，沒有將增加的公車班距導正為原來的班距，將造成公車結隊行駛的現象，影響公車業者正常的營運。 本研究將鐵、公路班表整合的形式分為三種：(1)班表不整合；(2)等班距整合；(3)整數比班距整合。並使用解析性數學模式分析不同班表整合形式下的鐵、公路適時轉運模式，最後選擇一範例來進行模式測試與敏感度分析，結果發現在班表未整合情況下，系統轉運成本將最高。而班表整合的方式，應以公車班表配合火車班表，亦即以火車班距為基準修正公車班距，使其能以等班距或整數比班距整合。

This study attempts to develop a timed transfer model for railway and bus route operations. Schedule synchronization with various routes in a transfer terminal may reduce transfer delay in the terminal. Since vehicle arrivals are stochastic, we may design slack time in the vehicle schedule to reduce the probability of missed connection of the transfer passengers. However, when slack time is in the schedule, it may result in vehicle operation cost increase, so we must consider it systematically. In the past, most of the literatures allowed focus on timed transfer models for buses. Because of the differences of operation characteristics of trains and buses, the factors considered in the timed transfer model for both modes are also different. The cost components in our timed transfer model include non-transfer cost and transfer cost. The non-transfer cost includes (1) vehicles operating cost;(2) passenger waiting cost in origin terminals; and(3) passenger in-vehicle cost. The total transfer cost function includes all cost components that are influenced by slack time and holding time. For example, if holding the bus departures at the transfer terminal, the induced cost on some compensated strategies (e.g. signal preemption) must be considered. Trains operate along a fixed track. As a result, they are not affected by other traffic situations and have higher schedule adherence. The rider-ship and operation cost of railway operations are also higher than buses, so it is not suitable for introducing a slack time in the train schedule. As train is late, we can adopt holding bus departure time to increase the successful transfer probability of train passengers. Similarly, holding time may increase bus operation cost and non-transfer passenger waiting cost. Besides, if we don't recall the initial bus headway, buses may possibly bunch together on the routes and will eventually influence the bus company's operation. There are three alternatives for integrating the schedules of railway and buses at the transfer terminal. They are (1) uncoordinated operating; (2) coordinated operating with common headway; and (3) coordinated operating with integer-ratio headway. We have applied an analytical model to explore the effects of different schedule coordination options. We also built an example for sensitivity tests. The results showed that the transfer cost of the system is higher than coordinated operations if the schedules were not coordinated. The policy of coordinated train schedules should be train schedule based. In addition, rather than a non-coordinated strategy, it is advantageous to use a common headway or an inter-ratio headway in our transfer system.