The Accessibility Impact of High Speed Rail in Italy: A User-Based Approach

Among the impacts that a High Speed Rail network has on a country’s society, economy and environment, the impact resulting from accessibility changes plays a key role. In fact, the main direct change generated by a new transportation system is the variation (generally a reduction) of travel times. This produces secondary effects as well, such as changes in accessibility, and shifts of transport demand from other modes of transport to rail. These changes generate other broader effects, which have an impact on various socio-economic and environmental issues, such as energy use, environmental structure, tourism, social dynamics, human health, safety, general economy, business clustering, labour productivity, land use, real estate, transport system resilience, technology development, innovation, and policies. While the concept of accessibility has been defined in several ways by various studies in the scientific literature, it usually refers to the ease of obtaining socioeconomic opportunities (activities, services, goods) within a geographic area or—from a more passive perspective—the ease with which such opportunities can be reached. While accessibility indicators can be distinguished by whether they focus on infrastructure, utilities, location, or even people, they are usually based on travel times between geographic locations. Although in continuous transport systems, such as road networks, travel times are highly significant for the purpose of depicting accessibility, that is not true for scheduled systems like collective ones, such as bus, rail, air, and maritime transport. In these latter cases, the onboard travel time is not fully representative of the user’s actual travel time, since the time spent accessing the transport system and the waiting time for services both play a crucial role in the users’ perception of accessibility. Several studies have been conducted to analyse the accessibility changes generated by the Italian High Speed Rail system built and put into service over the first two decades of this century. However, these studies have often focused on an accessibility concept based on service travel time, rather than on user travel time, including access and waiting times. This paper offers an analysis of the accessibility impact of High Speed Rail in Italy, focusing on a user-based approach. Accessibility indicators are therefore set up taking into account rail service timetables, and therefore the access to the services from the rail stations themselves, which, for the users, are the actual access points to the transport system. Moreover, the results of this user-based analysis are compared to the simple service travel time approach, in the order to estimate the differences and to highlight the methodological dissimilarities.