A long-term analysis of passenger flows on a regional rail line

Promoting rail systems can represent a useful policy for rebalancing modal choices and reducing private car use, especially in high-density contexts. Obviously, an increase in passenger numbers is only possible if generalized costs (i.e. a weighted sum of times and monetary costs) associated to public transport are abated. According to the recent literature and current professional practice, most strategies for achieving this objective are based only on infrastructural interventions which may be unfeasible or inadequate in densely populated contexts. Likewise, the adoption of policies based on replacing existing fleets or reducing fare levels entails increases in national or regional subsidies, which would be difficult to achieve in the current economic climate. Hence, our proposal is based on investigating effects on travel demand arising from the replacement or upgrading of existing signalling systems (both in terms of trackside and on-board equipment). Indeed, the recent European Union policy to create a single transnational interoperable rail network imposes the development of innovative signalling systems. In this context, since cost–benefit analysis has to be implemented to verify the economic and environmental feasibility of the proposed intervention strategy, an appropriate method should be developed to estimate passenger flows according to future configurations. In this article, we propose a method to determine travel demand in current and future contexts by appropriately processing data from Italy’s national census on mobility, population growth forecasts and turnstile counts. The proposed approach is applied to the regional Naples–Sorrento rail line serving the metropolitan area of Naples in southern Italy in order to show its feasibility.