Signal Setting and Paths Design for Road Supply Management in Evacuation Conditions
A Polimeni, A Quattrone, A Vitetta, F Alessandro Marciano, G Musolino, Mediterranea University of Reggio Calabria, IT
This work has three main objectives:
i) to simulate some evacuation operation at urban scale
ii) to calibrate some tools (hardware and software) for data recording
iii) to compare the observed data with those obtained from an optimization model
In this paper a part of a general methodology for the risk reduction in urban areas in terms of exposure through the definition and the implementation of evacuation procedures is proposed. The evacuation procedures allow to face catastrophic events both naturals (floods, hurricanes, wildfires, and so on) and man-made (nuclear and chemical accidents, terrorist attacks and so on).
In particular the subjects discussed in this paper concern the design to the best route for emergency vehicles to safe weak person, lacking in bodily strength or healthy vigour, as from age or sickness.
The design problem introduced above allow the emergency vehicles (ambulances) to rescue all weak people in the shortest time possible. A classical approach is the solution to a vehicle routing problem (VRP): note the user positions, the ambulance routes are designed to reach all users by minimizing the cost.
To identify the optimal routes, three steps can be followed:
1) cost evaluation, which can be achieved through one, or a combination, of the following: traffic assignment (TA) (static or dynamic), real-time system monitoring (RSM) or reverse assignment (RA);
2) one-to-one problem (OOP) solution, which consists, given the costs on the network obtained by the previous step, in generating alternative paths for each weak users pair;
3) many-to-one problem solution, which consists, given the optimal paths between every weak users pair obtained by solving the OOP, in the solution of a VRP formulated as a classic optimization problem whose objective is to calculate the best combination of one-to-one paths in order to visit all weak users in succession.
An ambulance route can be viewed equivalently as a sequence of users to visit or as a combination of paths (each path connects a pair of customers). In this sense, the shortest path search (or one-to-one problem) is a fundamental element to solve the vehicle routing problem (or one-to-many problem) with reliable costs.
In this paper three main aspects are developed.
Application to a real case is made to simulate an experience of evacuation planning for weak users due to a hypothetical forthcoming disaster executed in the within of SICURO project in the experimental test site of Melito Porto Salvo (Reggio Calabria, Italy).
Real case application is designed to detect the paths and stops of an ambulance to rescue some weak users. The survey data collected regarding the rescue of five weak users, the test site is part of the central area of the town where offices, residential and commercial activities are concentrated.
The instrumentation consisted of a PDA equipped with GPS tracking and software that mapped the points (to identify the paths) at fixed time intervals; the stops were identified interactively by an operator; by using the PDA other data were obtained to determine characteristics of the intervention (number of users, user location, and so on).
The arrival time at the user is indicated by the operator. The start is derived by analyzing the points that spatially coincide with the stop and assuming that the departure moment is the instant of observation of the last of these points. The stop duration (operation time) is calculated accordingly.
The data collected allow to calibrate a model for the costs estimation, known the costs is possible to solve the OOP and consequently the VRP.
Finally, the observed data (paths and routes) are compared with those obtained to applying the design approach proposed.
Association for European Transport