PSI - Issue 62

F. Silvestri et al. / Procedia Structural Integrity 62 (2024) 998–1005 F.Silvestri, A. Polimeni, O.M. Belcore/ Structural Integrity Procedia 00 (2019) 000 – 000

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• Car-Following Model Parameters. The car-following model simulates interactions between vehicles on the network. The model distinguishes two motion states for a vehicle: the state in which the vehicle travels along the road segment at the maximum speed allowed for that type of segment and the state in which the vehicle maintains a constant time gap from the vehicle in front. This time gap corresponds to the sum of the vehicle's reaction time and braking time. The following parameter values are generally used for the car-following model: reaction time, which represents the temporal safety gap between two consecutive vehicles, is set to 1.50 seconds for both light and heavy vehicles; effective length, which represents the sum of the vehicle's length and the distance it maintains from the vehicle in front when stopped in a queue, is set to 6.00 meters for light vehicles and 12.00 meters for heavy vehicles. 4. Application The case study relies on the A10 highway, considering the segment from Savona and Ventimiglia (on the border with France) in the Liguria region (north Italy). The highway stretch is 112 kilometers long and contains 18 tunnels (in Fig. 1 the three main tunnels considered in the study are reported). The SS1 road has been considered as an alternative route solution to divert a certain percentage of cars flows. For each tunnel, it is assumed that the works will be carried out in one direction of travel, thus closing a direction and diverting traffic onto a lane in the opposite direction. As a result, bypass points along the network have been located, which allow diversions of vehicular traffic, to define the segments subject to work zones. In both directions there is, for some links, a reduction in capacity as a result of the presence of the working zone, this impact on congestion and delays.

Fig. 1 – Location of the A10 Savona-Ventimiglia highway case study

4.1. Scenarios identification Two different scenarios have been identified: the first under the hypothesis of completing maintenance operations by the end of 2025 (scenario 1), the second by considering an extension for maintenance operations up to the end of 2028 (scenario 2). The schedule for scenario 1 includes interventions on 18 tunnels along 12 sections (from toll booth to toll booth) of the A10 Savona-Ventimiglia highway. Fig. 2 shows, for scenario 1, the maintenance scheduling by quarter for each tunnel subject to maintenance.