s a reliability Lift
steps in order to achieve the greatest benefit while avoiding unnecessary expense.
“For example we found that it would be possible to obtain more than half the expected 400% capacity increase in the first decade, while the running time reductions, which are achieved through new line sections, will be achieved more gradually,” Longo says. It is possible to use the same
approach to assess the minimum number of interventions required to operate a given number of services during special events which require more trains to meet demand, such as Expo 2015 in Milan. Here Lift has estimated the individual and combined impact on traffic of over 20 interventions such as signalling improvements, changes to the layout of stations, installation of faster switches, construction of flyovers, as well as new stops.
Each intervention was simulated
according to the real behaviour of trains, incorporating delays and stop times with the corresponding effect on traffic reliability under a given timetable. Lift says that the more the simulated delays were reduced by an intervention, the more the intervention was considered effective. Infrastructure manager Italian Rail Network (RFI) fully accepted the results of the study, continuing the design of
the selected set of interventions and discarding others which were shown to have a detrimental effect, including a stop in a strategic location in the city. Located between a major station and a junction it showed a significant impact on traffic reliability and therefore was dismissed despite its potential benefits.
Lift similarly estimates the reliability that could be obtained by adopting a new timetable. In 2009 the team was asked to estimate the reliability of the Milan - Rome Frecciarossa high-speed services running on the new Milan - Bologna high-speed line and their effect on other trains. “With over 1000 trains, 13,000 itineraries and 5000 signals on a 500km line the simulation was a real challenge, especially concerning dispatching within Milan Central station, where up to six simultaneous movements are possible although no flyover is provided,” says Lift president Mr Giorgio Mederossi. The model was first carefully calibrated using real operational data to accurately reproduce the dispatching rules used by operators. Secondly, the new timetable was simulated under those conditions in order to estimate the punctuality that could realistically be obtained with the new infrastructure and timetable. A series of delay scenarios was also defined and
simulated to estimate the decrease in reliability under certain conditions, and in particular the effect caused by delays on a specific line on other services. The results of the simulation showed a higher robustness of the 2010 timetable compared with the 2009 version with the lower anticipated impact of traffic conflicts resulting in higher expected punctuality levels. While these results are proof of the quality of the new timetable, the possibility of variations in the behaviour of the dispatcher and the initial delays were also used to simulate the most frequent delay scenarios. By estimating their impact in presence of different dispatching criteria it is possible to suggest to the infrastructure manager ways to minimise their impact on operations and as a result reduce delays.
Lift is now working in South America, where it is currently designing the operations on the planned Line 2 of Metro Lima. In Norway its approaches and tools are allowing infrastructure manager Jernbaneverket to analyse the performance of timetables and accurately estimate the impact of infrastructure improvements. And with railways constantly looking to identify ways to get more from what they have, these tools could be invaluable in these operators’ efforts to achieve high availability and reliability. IRJ
Lift developed the timetable for Trenitalia’s Frecciarossa services on the Milan - Bologna high-speed line.
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