Efficiency of the trackwork scheduling process in Sweden

Abstract: Efficient scheduling is vital for railway maintenance, which is increasingly challenged by rising train traffic and infrastructure wear. Trackwork often necessitates the reduction of train speeds and the partial or complete closure of tracks. Despite advancements in maintenance technology, the efficiency of planning processes, especially the repetitive tasks of planners and the adaptation to unforeseen events, have been under-addressed.This thesis delves into the topic of trackwork scheduling efficiency in Sweden and analyses the current process through the lens of Lean philosophy. In this thesis, ‘trackwork’ specifically denotes preventive maintenance of railway infrastructure requiring temporary capacity restrictions, excluding renewal works that also fall under this definition but are outside the scope of this thesis. The goal of this research is to identify the main factors that affect scheduling efficiency in trackwork management and discuss potential strategies to evaluate and improve efficiency. In assessing scheduling efficiency, the focus is on the time dimension, where an efficient trackwork schedule involves utilising 100% of the booked time on the track, with waste defined as trackwork rescheduling or any avoidable disruption to train operations. In the context of trackwork scheduling, this might be caused by overscheduled possession time, where trackwork takes significantly less time than allocated, or underestimated maintenance duration, where trackwork completion exceeds the allocated on-track time. Following the Lean framework, the five papers comprising this thesis correspond to the six practices of Lean production: elimination of waste, pursuit of zero defects, pull instead of push, decentralisation of responsibilities, a vertical information system, and continuous improvement. All six practices are emphasised in the aims and contributions of each of the five papers. Paper 1 describes the trackwork planning and scheduling process in the context of the Lean framework. Papers 2 and 4 are designed to explain the factors influencing changes in the trackwork schedule, drawing on empirical evidence from an interview study and logistic regression modelling. Papers 1, 3, and 4 suggest percent plan complete and schedule instability as methods of evaluating trackwork scheduling efficiency.The qualitative and quantitative analyses of the trackwork scheduling and execution process reveal the nature of schedule changes and demonstrate how trackwork affects train traffic. The results indicate that the efficiency of trackwork scheduling is influenced by external and internal railway maintenance project uncertainties, a lack of trust between project managers and contractors, and poor knowledge transfer within contracting companies. Schedule changes may also derive from changes in contract terms, additional maintenance project requests from the Swedish Transport Administration, or shortages of specialists in specific technical areas, infrastructure failures, or urgent repair needs. Additionally, the consequences of inefficient scheduling are quantified: trains passing scheduled trackwork 1.43 times are more likely to experience delays of least one minute, and the risk of delay is higher for trains scheduled on double-track railway segments.This thesis recommends the implementation of consistent measures to assess trackwork scheduling efficiency, applicable across strategic, tactical, and operational levels. These include regular assessments of maintenance window utilisation, estimation of trackwork schedule stability, and analysis of the impact on train traffic. This approach aims to provide a clear understanding of the scheduling's effectiveness in railway operations.