# An Overview of Shared Mobility Operational Models in Europe
## 1 Introduction  
The availability of shared mobility services, such as carsharing, bikesharing, and e-scooter sharing, has increased in recent years. Although these services are developed, the businesses that offer them typically shut down, with the majority doing so in five years or fewer [1]. While Europe is committing to reduce transport sector emissions by 90% in 2050 and for cars and vans by 100% in 2035 [2], shared mobility is one of the key strategies to achieve that goal. Shared mobility is based on the idea that individuals should use shared resources as needed rather than owning their own vehicles. In Europe, cars are often parked 92% of the time [3]. In this regard, Europe's Smart and Sustainable Mobility strategy stresses the importance of shared and collaborative mobility services to reduce the pressure on passenger transport systems [4]. Shared mobility is a broad term that encompasses different services, such as bicycle, car, and scooter sharing [5]. It offers a range of choices, from services that share cars, such as station-based or free-floating carsharing, to bike and e-scooter sharing, and services that share rides [6]. Carsharing is a service that provides short-term car rentals, which allows users to use vehicles at any time of the day for any length of the rental period. Carsharing began as a small cooperative of people who wanted to share the use of private vehicles. Later, systems were developed based on fleets of vehicles that can be rented on a minute-or hourly basis. In contrast to the low perceived expenses of private car ownership, carsharing helps drivers become more conscious of the variable costs connected with each journey, which, in turn, reduces the kilometers driven. Carsharing inhibits spontaneous travel and encourages other forms of transportation, such as bicycling, carpooling, and public transportation, by requiring reservations and planning [6, 7, 8]. Bikesharing, the shared use of a bicycle fleet, is a mobility strategy that could reduce transport sector emissions and achieve the goal set by the European Commission. Theprinciple of bikesharing is that individuals use bicycles on an as-needed basis without the costs and responsibilities of bicycle ownership. Commonly concentrated in urban settings, bikesharing programs also provide multiple bike station locations that enable users to pick up and return bicycles to different stations. Bikesharing programs typically cover bicycle purchase and maintenance costs, as well as storage and parking responsibilities (similar to carsharing or short-term automobile use) [9]. Micromobility has recently gained significant interest all over the world, mainly due to electric scooter services. This new transportation system concerns the use of shared e-scooters for urban routes, supporting urban mobility in a flexible and economic way [10]. In addition to offering last-mile options and supplementary ways to use public transportation, it could aid in lowering traffic externalities [11]. Scooter sharing is divided into two types of services: standing electric scooters and moped-style scooters [12]. This paper will explore three key modalities of shared mobility: carsharing, bikesharing, and scooter sharing, highlighting their development, benefits, and operational models. The first section focuses on carsharing, a service that allows users to rent cars on a short-term basis. This model is revolutionizing urban mobility by providing flexible access to vehicles without the burden of ownership. By enabling access to cars around the clock, carsharing services have been shown to reduce the number of privately owned vehicles, contributing to lower greenhouse gas emissions and a shift toward more sustainable transportation methods. Various business models and operational models of carsharing will be discussed to offer a comprehensive understanding of how this service functions. Relatively few studies have focused on fleet optimization for carsharing.