隨機派翠網路應用於臺鐵捷運化之運行調度模擬模式建構與分析

SIMULATION MODELLING AND ANALYSIS OF TAIWAN RAILWAY ADMINISTRATION’S MRT-TYPE OPERATIONS BY USING STOCHASTIC PETRI NETS

近年來臺灣鐵路管理局鐵推動「臺鐵捷運化」政策，其目的在於將臺鐵運輸系統轉變為具有近似「大眾捷運系統」的特性。本研究採用可提供具可視化描述功能與系統動態活動描述功能的隨機派翠網路（stochastic Petri nets）為基礎之資訊系統開發方法組合（set of information system development method, SISDM），作為軌道運輸運行調度模擬模式建構與分析之開發方法。首先，蒐集與彙整臺鐵局提供之相關資料與自行調查之分析結果，然後建構以隨機派翠網路為基礎之臺鐵捷運化列車運行調度模擬模式，並以基隆－－中壢段為模擬模式之驗證案例，再藉由發車間距、列車組成與調度等情境分析，研析臺鐵捷運化之運行調度策略。經由模擬分析結果顯示，臺鐵捷運化後之列車發車間距，在系統車輛數允許之情況下，以間距240秒最能發揮整體運輸效率。在列車組成部分，當慢車與快車之列車組成比例為1：1且為交錯組成時，較適合發車間距較長之列車運轉；當慢車與快車組成比例為2：1時，無論發車間距多寡，皆能發揮最佳之整體運輸效率；當慢車與快車組成比例達3：1時，則較適合發車間距較密集之列車運轉。在調度策略部分，採用特開列車策略對於因延誤發生而受影響之列車運行時間雖無明顯改善，但卻能有效回復受影響之發車間距，減少延誤所產生之影響。

To transform the railway transportation system into the system with MRT’s characteristics, Taiwan Railways Administration(TRA) has promoted a policy called “Transformation of the Taiwan Railway into a MRT-type railroad” for the past few years. This study presents the SISDM based on Stochastic Petri Nets (SPN) describing visualized functions and system dynamic activity functions which can be regarded as a toolkit of railway operations simulation modeling and analysis. First, related data provided by TRA and results of own surveys are collected and summarized. Then, a simulation model based on the SPN is developed to analyze TRA’s train operations and dispatching strategies similar to MRT-type operations. By taking Keelung-Chungli southbound line as the empirical study, numerous simulations are performed with various scenarios including different headways, train types, timetable delays. Having implemented transformation of the Taiwan Railway into a MRT-type railroad policy, the simulation results indicate the total system efficiency will be optimal with the average headway 240 s if train cars are assumed to be available. Longer headway operations are suitable when the proportional combination between slow and express train types is 1 to 1. No matter how long or short the headway is, the total system efficiency will be optimal when the proportional combination is 2 to 1. Nevertheless, shorter headway operations are preferred when the proportional combination is 3 to 1. Although the strategy of increasing special frequency to reduce timetable delay is not significant to eliminate propagation impacts of timetable, it is still very effective to maintain regular headways.