A. Polimeni

Safety of Users in Road Evacuation: Design of Path Choice Models for Emergency Vehicles

Within the framework of the SICURO research project, the main objective of this paper is to define the procedures that were planned and activated in emergencies in order to allow the evacuation of weak users (disabled, old persons, etc.) from the area affected by a disaster and design the optimal path for emergency vehicles to reduce evacuation times. Specification, calibration and validation of a path choice generation model in order to simulate the behavior of emergency vehicle drivers at an urban level during an evacuation is proposed. The authors specify the factors that affect path choice behavior and the two main approaches: one to one and many to one. The first regards the minimization of generalized cost of a path that connects an origin to a destination; the second instead considers the connection of one origin to many destinations. The authors report some experimental results, obtained in the context of the SICURO Project, by applying the proposed model to a real road transport network at urban scale during a simulation of an evacuation.

Safety of Users in Road Evacuation: Algorithms for Path Design of Emergency Vehicles

This paper on the path design of emergency vehicles is from the proceedings of 14th international Conference on Urban Transport and the Environment in the 21st Century, which was held in Malta in 2008. This paper is one of five papers that focus on the safety of users in road evacuation. In this paper, the authors propose an advancement relating to the design of path choice models for emergency vehicles is proposed. They focus on how the procedures to be planned and activated in emergency conditions were defined in order to allow the evacuation of weak users (the disabled, senior citizens, etc.) from the area affected by a disaster. In addition, some advanced instruments and scenarios for designing the optimal path for emergency vehicles to reduce evacuation times are introduced. The authors use the SICURO research project data, carried out by the Laboratory for Transport Systems Analysis (LAST) of the Mediterranea University of Reggio Calabria in Italy. The problem of an emergency vehicle that has to pick up some users at fixed points of the network and to take them to the refuge area is schematized (as in a previous work) with two different approaches: as a shortest-path problem (one to one) and as a vehicle routing problem (many to one). The authors describe two different algorithms: the k shortest paths algorithm is applied to obtain the best k paths that satisfy specific choice criteria; and a metaheuristic procedure (genetic algorithm) which allows route optimization of a fleet of emergency vehicles.

Safety of Users in Road Evacuation: Modelling and DSS for Paths Design of Emergency Vehicles

This paper deals with path design for emergency vehicles (ambulances) in emergency conditions (hurricanes, earthquakes, etc.). These vehicles are intended to rescue weak users (the elderly, disabled persons, etc.). The problem of an emergency vehicle picking up weak users at fixed points of the network and takes them to the refuge area is schematized with two different approaches: one-to-one and many-to-one. The first regards the minimization of generalized cost of a path that connects an origin to a destination (as a shortest-path problem); the second considers the connection of one origin to many destinations (as a vehicle routing problem). Starting from a brief review of both these problems, the available tools for planning evacuation of weak users in emergency condition in the within of one to- one and many-to-one are analyzed. Finally, on the basis of a real simulation of evacuation, the authors provide experimental results obtained by testing the effectiveness of a commercial tool when little time is available for planning evacuation operations.

Optimising Waiting at Nodes in Time-Dependent Networks: Cost Functions and Applications

In this paper, the relationship between waiting at nodes and the path cost in a transport network is analysed. An exact solution algorithm for generating the shortest path with optimal waiting at the nodes is proposed. The general case is examined, considering a time-dependent network (time influences the cost). To develop a full application, the algorithm is applied in the case of a vehicle routing problem on a real network.

Dynamic Vehicle Routing in Road Evacuation: A Model for Route Design

The shortest path and route problem in time-dependent networks are treated in this paper. The system can be in ordinary or emergency conditions. Path design formulation is based on dynamic programming and its solution is found through a modification of Dijkstra’s algorithm. Route design, starting from the designed paths, is formulated as an optimum problem. In emergency conditions the main objective is to optimize emergency vehicle tour to reduce the intervention time or maximize the number of people rescued in a fixed time.

Dynamic vehicle routing in road evacuation: route design experimentation

This paper reports on a procedure to find shortest paths and an application on the route design problem in a time-dependent network. In the application on the real network, the data, which are obtained with real-time observations, are integrated with forecast data to define the costs on non-observed network elements that were obtained from a dynamic traffic simulation. The real case application is performed in emergency conditions and the aim is to optimize emergency vehicle routes (defined as a path succession) to reduce intervention times.

Vehicle routing in urban areas: an optimal approach with cost function calibration

In this paper, a multi-step model related to freight movements in urban areas is formalised to solve a Vehicle Routing Problem with Time Windows (VRPTW). In modelling terms, the VRPTW is formulated to consider the optimum paths between all the customers combined to determine the best vehicle routes. The optimum path search with a selective mono-criterion approach is tackled. A model for forecasting the link cost is calibrated. Some procedures (traffic assignment, real-time system measurement, reverse assignment) for estimating system performance in terms of travel cost are also proposed. In terms of procedures, the VRPTW is solved with a genetic algorithm and two different crossover operators are reported and used simultaneously. A real case application is made, comparing the results of the proposed procedure with the routes of a truck (<6 tonnes) delivering dairy products to some retailers in a city. The contribution of this paper is to relate the Vehicle Routing Problem (VRP) to transport the network theory. Indeed, the VRP is generally treated without considering network congestion. In the approach proposed in this paper, the costs are assumed to be functions of network characteristics and traffic flow, while a model for forecasting link costs is calibrated from real data.

A Tool for Tracing Emergency Vehicles During Evacuation

Emergency evacuation management can be identified by a planning phase and an operation phase. This paper will discuss the design of the best routes for emergency vehicles to save weak users. The design problem is formalized in order to allow the emergency vehicles (ambulances) to rescue all weak users in the shortest time. In this paper a hardware-software tool that can be used to collect real-time data for the implementation of the proposed models is analyzed. The tool is designed to identify the paths (mapping the vehicle position at fixed time intervals) and to register the vehicle stops at the weak user’s location.

A comparison of vehicle routing approaches with link costs variability: an application for a city logistic plan

In this paper the comparisons of some solution approaches for vehicle routing are reported. The scenarios of vehicle routing with static travel costs, pseudodynamic travel costs, dynamic travel costs are considered. Some characteristics of link costs are discussed. For each scenario the changes in vehicle routing (i.e. path search) are highlighted; a test application for freight distribution in city logistic is done. The goal is to verify how the cost variation in the time influences the route optimization.

An Ex-ante Evaluation of Last-mile Freight Distribution Services for City Logistics

The paper deals with methodologies to support an ex-ante assessment of the impacts generated by the introduction of city logistics measures on last-mile freight distribution services. Some models and algorithms are applied and compared to solve the vehicle routing problem for freight deliveries in the town of Reggio Calabria with the introduction of an urban distribution centre and of green freight vehicles. Heuristic routing algorithms are compared in terms of sequence of clients (retailers) visited subject to some constraints given by the presence of UDC and the limited autonomy and capacity of freight vehicles.