A multi-objective model for fair location of stations and geofence parking area to address disorderly parking in free-floating micromobility systems

Transport within cities has been significantly changed by micromobility, particularly with the spread of shared systems. There are two types of these systems: station-based and free-floating. The former is characterised by the presence of stations in which a user can pick up or drop off a vehicle. The latter offers users the same functions but, where enabled, anywhere within the service area. Free-floating systems may appear more equitable and convenient than station-based ones, as stated in literature, but on the other hand, they can lead to unauthorised and irregular parking, obstructing pedestrians and vehicle flow. To reduce disordered parking, one of the possible solutions is to implement stations also in free-floating systems. However, this can reduce their attractiveness, forcing users to walk longer and making the system less fair. To address these issues, we proposed to convert a free-floating system into a mixed one with free-floating and station-based geofenced service sub-areas. The station locations are defined through a new multi-objective problem with the aim of finding a compromise among three objectives: the maximisation of drop-off station demand to minimise irregular parking, the minimisation of users’ walking distances in active and passive accessibility, and the minimisation of inequality in walking distance changes due to the conversion to a mixed system. This model was applied to a real case study and shows that our proposal can be of help for municipalities and operators in choosing fair station locations or a trade-off solution based on the importance they attach for one objective compared to the others.