Assessing Accessibility to Regional Hubs Through Integrated DRT–Rail Services: Evidence from a Case Study in Southern Italy

Demand-responsive transport (DRT) services are increasingly recognised as an effective solution for enhancing accessibility, particularly in low-demand and peripheral areas. Existing scientific research has investigated DRT as a feeder service to modal interchange nodes, with a specific focus on railway hubs. In this study, an accessibility indicator is developed to compare direct road-based access to regional hubs with multimodal access combining road and rail, enabled by DRT services. The indicator is derived from a detailed analysis of road travel times and scheduled rail services and is applied within a regional-scale framework. Under the hypothesis that travel originates in the centre of each municipality in the area under consideration, two travel times are calculated: the time for the road alternative, based on the characteristics of the road network, and the time for the combined alternative, based on the attributes of the rail network. The resulting indicator allows for identification of the alternative that is more time-competitive for medium-distance travel on a regional scale and for mapping accessibility to attraction centres on a municipal basis. The methodology is applied to a case study in Sicily, Southern Italy. The analysis considers trips from all Sicilian municipalities to the metropolitan areas of Palermo, Catania, and Messina, assessing both the current situation and future scenarios based on planned railway infrastructure upgrades. The results indicate that, while direct road access remains the most efficient option for a large share of municipalities, the multimodal DRT–rail alternative becomes competitive in areas located near railway stations, particularly under scenarios that include major rail interventions, such as the upgrading and speed enhancement of the Palermo–Catania railway corridor.