Estimation of the propagation of delays: Comparison between analytical methodologies and simulation approaches in the case study of the line “direttissima” rome-florence

The aspects related to the frequency of the service, travel time and punctuality are becoming increasingly important for passenger satisfaction and the expected level of quality. In fact, delay is one of the major issues that rail systems around the world are facing through predictive analyses and mitigating actions. The railway timetable therefore requires the best trade-off between the elements connected to the capacity of the infrastructure, in terms of train paths that can be allocated, and the regularity of the service. This work investigates the effects of delay propagation in relation to a given value of the number of trains circulating in the unit of time. The study environment has the Rome-Florence “Direttissima” high-speed line as its reference, the backbone of the Turin-Milan-Naples high-speed dorsal. Thus, we want to study the response of the railway system to the variation of the headway between the trains and in the presence of a source of delay. The phenomenon is described below, first from an analytical point of view under defined ideal conditions and, subsequently, with the support of the OpenTrack© railway simulation software considering some timetable configurations. Lastly, the various methodologies used are compared with each other. Therefore, some useful indications could be obtained especially in the construction phase of the railway timetable structure and in the management of traffic.