No abstract

No abstract

No abstract

Traditional car sharing systems are round trip shared vehicle systems and require advance reservations. The advances of GPS, communication techniques and vehicle automation allow us to improve car-sharing systems and to provide users with greater flexibility. As it concerns reservation, new car sharing systems offer users open-ended reservation and/or instant access. As it concerns the trip topology, new car sharing systems are multiple station shared vehicle systems (MSSVS). Round trips still occur in this type of system; however there are a large number of one-way trips made between the multiple stations. Operating an MSSVS is much more difficult than operating a round trip shared vehicle system. The problem is that the system can quickly become imbalanced with respect to the number of vehicles at the multiple stations. A review of user-based and operator-based relocation strategies is provided in the paper, as well as some details about some new possible car sharing systems, where vehicles are fully automated and can be accessed from any point within the intervention area.

Purpose The paper concerns a transport system for pedestrian areas, based on a fleet of fully-automated Personal Intelligent Accessible Vehicles. The following services are provided: instant access, open ended reservation and one way trips. All these features provide users with high flexibility, but create a problem of uneven distribution of vehicles among the stations. A fully vehicle based relocation strategy is proposed: when a relocation is required vehicles automatically move among stations. The paper focuses on a methodology that allows to plan the proposed transport system for wide pedestrian areas. The methodology aims to determine the fleet dimension and the relocation strategy parameters which minimize the system cost. The system cost takes into account the level of service and the efficiency. Relocation strategy parameters define when and among which stations relocations should be performed. Methods The problem faced is an optimisation problem where the search space is defined by all the possible fleet dimensions and relocation strategy parameters. As this cost function could be a multipeak function and since the search space is discrete and extremely large, a random search algorithm has been adopted. Because of the characteristics of the problem, a parallel optimization technique was required. Given a fleet dimension and relocation strategy parameters, a microsimulator models the activity of each user, as well as the activity of each vehicle over time with the aim of finding the level of service and the system efficiency.Results, conclusions and application The methodology has been applied to planning the proposed transport system for the centre of Barreiro, Portugal.

No abstract

This paper concerns an innovative methodology aimed towards specifying the best evacuation plan in a given scenario - where a scenario is characterised by the enclosure geometry, the population’s capabilities and the population distribution within the building. The best evacuation plan is assumed to be the one which minimises the movement time of the last evacuee. The problem faced is an optimisation problem where the cost function to be minimised is the last evacuee’s movement time and the research space is defined by all the possible evacuation plans in the given scenario. As this cost function could be a multi-peak function and since the research space is discrete and extremely large, a random search algorithm has been adopted. Given an evacuation plan, the proposed methodology models the evacuation over time with the aim of finding the movement time of the last evacuee. The modelling of the evacuation over time has to obey to two criteria. First, as it is embedded in the optimisation process and it has to be repeated a very high number of times (potentially for each possible evacuation plan), the computational cost is a critical issue: therefore the model has to be “synthetic” and microscopic models result not suitable. Secondly, the model cannot neglect flight behaviour and crowd crushes: therefore the need for a Dynamic Network Loading model which allows to keep track of the location of moving queues in the network, to predict spillbacks and dissipation and to model capacity drop due to clogging effects as well. The overall model has been implemented in an object-oriented simulator that allows analysis of large multi-floor buildings. The simulator has been applied to an illustrative problem of evaluating the best evacuation plan for a school: the application results are reported in the paper. The methodology application field is the straight forward evacuation, before the onset of hazardous conditions. In this context, the best evacuation plan is chosen off-line and the building occupants could be trained on the escape routes they have to follow from their origin rooms to the exit

Purpose The paper refers to an innovative urban freight distribution scheme, aimed at reducing the externalities connected with the freight delivery process. Both packages destined to commercial activities and to end consumers (e-commerce) are taken into account. Each package is characterized by an address and dimensions. In the proposed transport system, freight is firstly delivered to the UDC on the border of urban areas through trucks or trains which perform the long distance transport. After, freight is reorganized and consolidated into load units, i.e. the FURBOT boxes, according to packages dimensions and to the addresses of receivers. Each box is addressed to a temporary unloading bay and it is delivered there by a FURBOT vehicle. The receivers are in charge of collecting their packages in the related unloading bays where they have been delivered. Methods and results The paper concerns a methodology for optimizing this freight transport system's performances. The overall methodology receives in input the actual freight demand and the road network, and finds the transport system parameters (number of required FURBOT boxes, their temporary unloading bay, the FURBOT fleet dimension and the FURBOT vehicle routing) that minimize the system overall cost. The overall cost is a sum of the users' cost, which depends on the distance they have to walk for collecting their packages in the FURBOT box, and of the operator's cost, which depends on the number of required boxes, the total distance travelled by the FURBOT vehicles and the required number of FURBOT vehicles. Application The overall procedure has been applied to the case study of Barreiro old town, a suburb of Lisbon, Portugal.