Investigating the effect of temporal and spatial flexibility on the performance of one-way electric carsharing systems Burak Boyacı a,* , Konstantinos G. Zografos a a Centre for Transport and Logistics (CENTRAL), Lancaster University Management School, Lancaster, LA1 4YX, UK Abstract One-way electric carsharing systems provide an environmentally friendly option for facilitating urban mobility needs. However, the management of one-way electric carsharing systems presents operational challenges stemming from the need to relocate cars in order to strike an optimum balance between demand and supply. As a result, the cost associated with vehicle relocation operations represents a significant proportion of the total operating cost. The introduction of temporal and spatial flexibility regarding the pick-up and drop-off of vehicles provides the means of improving the efficiency of one-way electric carsharing systems. However, the literature currently lacks models that can be used to investigate the effect of temporal and spatial flexibility on the performance of one-way electric carsharing systems. In this paper, we are introducing an integrated modeling and solution framework for investigating the effect of temporal and/or spatial flexibility, and different reservation options to the profitability and utilization of one-way electric carsharing systems. The application of the proposed framework to a realistic size system suggests that spatial flexibility has a stronger effect on the system performance than temporal flexibility. Furthermore, both spatial and temporal flexibility can increase the profitability of the system by serving more customers with fewer vehicle relocation needs. Keywords: one-way carsharing, vehicle relocation optimization, integer programming, network flow 1. Introduction In 2014, more than 54% of the world population was living in urban areas. By 2060 it is expected this ratio will go up to 66% (UN, 2014). In order to deal with increased population with limited resources, local and regional governments try to decrease private-use vehicles with disincentives such as congestion-pricing and increased taxation. Although these measures encourage some city dwellers to choose more societal-friendly options, there is still a sig- nificant proportion of trips that are unavoidably require driving a vehicle. One of the environmental-friendly options of having the option of providing mobility on demand without owning one is using a shared-use vehicle system (e.g. bikesharing, carsharing) (Shaheen et al., 2015). Carsharing is a more accessible and efficient car rental concept usually for a short period of time. Different than the conventional car rental, in a carsharing system, users have self-service access to vehicles scattered around the city throughout the day. Thanks to rapid improvements in the mobile communication technologies, users are provided with a contactless card and an dedicated app that allows them to locate and access vehicles. When someone becomes member of the service, he/she gains access to vehicles (in some cases located in multiple cities) without any time limitation in a short period of time. Carsharing has various benefits to environment and society as a whole. By eliminating the cost of owning a car, it reduces the personal transportation cost, increases mobility to disadvantaged groups and encourages people to prefer more environmental-friendly alternatives. It decreases vehicle kilometers travelled, congestion and emissions eventually (Crane et al., 2012). Each shared-use vehicles removes 7-10 privately owned vehicles from the streets (Shaheen et al., 2015). * Corresponding author Email addresses: b.boyaci@lancaster.ac.uk (Burak Boyacı), k.zografos@lancaster.ac.uk (Konstantinos G. Zografos) Preprint submitted to Transportation Research Part B: Methodological December 14, 2018