Introduction to the special issue on shared mobility systems

Operational Research, 2020

The purpose of this paper is to propose a holistic optimization-based framework for addressing the re-balancing problem of vehicle-sharing schemes. In order to address this issue, the problem is decomposed into three (3) sub-problems that include: (1) the dynamic prediction of vehicle demand in stations or zones (in the case of freefloating systems); (2) the optimization of the assignment of vehicles from stations/ zones using the predicted demand of the first step; and (3) the optimization of the route that the re-balancing vehicle should follow, under transverse distance minimization objectives, and given the optimized assignment of the second step. As the route optimization of the rebalancing vehicle is computationally intensive, a heuristic algorithm is developed that transforms the route optimization problem into the one (1)-Commodity Pickup and Delivery Capacitated Traveling Salesman Problem. The applicability of the proposed methodology is illustrated through its application on the real case of the bike-sharing system in the city of Thessaloniki in Greece.

European Transport Research Review, 2013

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.

Transportation Research Part C-emerging Technologies

The paper concerns the conceptual design of a transport system for pedestrian areas. The proposed transport system is based on a fleet of eco-sustainable Personal Intelligent City Accessible Vehicles (PICAVs). The vehicles are shared through the day by different users and the following specific services will be provided: instant access, open ended reservation and one way trips. Referring to the proposed transport system, a new methodology to optimise the fleet dimension and its distribution among the stations is proposed in this paper. The problem faced is an optimisation problem where the cost function to be minimised takes into account both the transport system cost and the user costs that depend on the waiting times. A random search algorithm has been adopted. Given a fleet dimension and its distribution among the stations, the waiting times of the users are assessed by a microscopic simulation. The simulation model tracks the second-by-second activity of each PICAV user, as well as the second-by-second activity of each vehicle. The overall methodology has been implemented in an object-oriented simulator. The proposed transport system has been planned and simulated for the historical city centre of Genoa, Italy.

Carsharing is a model of renting vehicles for short periods of time, where the payment is made according to the time and distance effectively traveled. Carsharing offers a simple, economical and smart alternative to urban mobility, that is already being adopted in the major cities in the world. The proposed methodology consisted in the development of a decision support system that simplifies the process of choosing carsharing services. Adopting the AHP method, the user can indicate their preferences in the choice of vehicles, and the system returns an ordered list of the most suitable available vehicles based on their geographic location. The findings of the project indicate that the use of this system encourage and simplify the use of carsharing services, which will allow to enhance the financial, mobility and environment advantages inherent to their use.

Transportation Planning and Technology, 2015

In this paper, three innovative car-sharing systems for urban areas are proposed, based on fleets of individual intelligent vehicles with three service characteristics: instant access, open-ended reservations and one-way trips. These features provide high flexibility but create an uneven distribution of vehicles among stations. Therefore, relocation of vehicles must be performed. Three different system procedures are proposed: in the first system, relocations are performed by users; in the other two, vehicles relocate automatically, thanks to their automation. In the first two systems, vehicles are accessible only at stations, whereas in the third they are also accessible along roads. In order to provide transport managers with a tool to test systems in different realities, an object-oriented simulator is developed. The simulation provides outputs of system performance, in terms of user waiting times and system efficiency. The proposed systems are simulated for the city of Genoa, in Italy, and a comparative analysis is presented.

ArXiv, 2017

Carsharing is a model of renting vehicles for short periods of time, where the payment is made according to the time and distance effectively traveled. Carsharing offers a simple, economical and smart alternative to urban mobility, that is already being adopted in the major cities in the world. The proposed methodology consisted in the development of a decision support system that simplifies the process of choosing carsharing services. Adopting the AHP method, the user can indicate their preferences in the choice of vehicles, and the system returns an ordered list of the most suitable available vehicles based on their geographic location. The findings of the project indicate that the use of this system encourage and simplify the use of carsharing services, which will allow to enhance the financial, mobility and environment advantages inherent to their use.

Annals of Computer Science and Information Systems

International Journal of Computer Applications

Carpooling or ride-sharing systems are considered to be an economical efficient method to solve many traffic problems. Carpooling allows drivers to share their journeys with other passengers. This reduces passenger fares and travel time, in addition to traffic congestion, while also increasing driver income. So, several carpooling systems have been introduced in recent years. This research proposed a ridesharing analysis framework to find the shortest route between any two carpooling system nodes. Also, to represent how the matching process between passengers and drivers can be performed in an economical and efficient method to study the profitability for passenger/s and driver/s. The framework was applied to real carsharing test data and the recorded results showed a 40% saving for passengers and a high level of added revenue for drivers compared to the existing systems in the market.

Analyses of Social Issues and Public Policy, 2003

The concept of car sharing is introduced as an innovative approach to the growing transportation problems of the major metropolitan areas of the United States. After sketching the history of car sharing in Europe and North America, three studies of the early adopters of Car Sharing Portland (CSP), the first commercial car sharing organization in this country, are reported. Study 1 found that these individuals were primarily motivated to join CSP because of their occasional need for a vehicle and secondarily by the financial savings they expected to realize by becoming a member.

Carsharing organizations are shared-mobility services which allow users to share vehicles of a fleet. These services are divided into one-way and two-way systems. Two-way systems require users to return the vehicles to their original pick up stations whereas one-ways systems do not. We present a hybrid system that has features of both. Two integer programming optimization models are formulated. The first model, called the fleet size problem (FSP), is for tactical planning and calculates the required fleet size in order to answer all the demand in various market segments where every market segment is composed of some direct-trip and some round-trip users. This model also accounts for vehicle relocation between stations. In reality, however, fleet size is fixed for day-to-day operations. With a specified fleet size, not all users are necessarily served unless the fleet size is quite large compared to the demand. Therefore, a second operational model, called profit maximization problem (PMP), selects from a list of user requests those who profit the service-provider the most. Data from Autoshare, a carsharing company in Toronto, is used to assess the models. Results of the FSP model indicate that one-way systems require the lowest fleet size but highest vehicle relocation hours. Two-way systems are relatively insensitive to the market segment and the hybrid system’s performance is dependent on the market segment scenario. The PMP model shows that the one-way (two-way) system is most beneficial to direct-trip (round-trip) users. The hybrid system is the only system without user surplus costs.