The effects of a real-time public transport information app on travel behaviour, traffic levels and the environment

Advanced Traveller Information Systems (ATIS) have been shown to improve travel satisfaction and to make public transport more attractive, but their effect on traffic, travel behaviour, and environmental externalities remains an open question. Addressing these questions is key to determining the impact of policies supporting ATIS in sustainability outputs. In this paper, we study the case of Red, a nationwide real-time public transport mobile application in Chile. Through a survey conducted on the app, we analyse the effects that the use of the app has on modal choice, public transport demand, vehicle kilometres travelled (VKT) and environmental externalities. One of the surveys questions was the counterfactual mode: we asked participants which mode they would have used in their latest trip if they did not have access to the app. Contrasting this with the revealed mode used in the latest trip, allowed us to estimate the modal substitution rate. We performed Monte Carlo simulations to estimate the Red effect on total VKT and environmental pollution. We find that: (i) when using Red, perceived waiting time decreased and personal security improved, (ii) 23.5% of the Red users changed their travel behaviour: 10.5% changed travel mode change and 13.6% chose another bus route or bus stop because of using Red (iii) urban buses gain and lose passengers (3:2 ratio, with a net increase in demand), competing mainly with shared taxis and ride-hailing, (iv) the induced demand for public transport is 1.1%, (v) the app reduces total VKT (probability P=0.99), and CO ₂ emissions (88%), and (vi) variation on local air pollutant emissions depends on vehicles environmental standards, decreasing only under high standards (Euro VI). Our method was applied to the case of an ATIS app, but is suitable to analyse the sustainability effects of any policy that increases public transport demand.