Assessing the impact of fare-free public transport on ridership. The case of Clermont Auvergne Metropole[Évaluation de l’impact de la gratuité des transports en commun sur leur fréquentation. Application au cas de Clermont Auvergne Métropole]

In a context marked by climate change and, more broadly, by a profound environmental crisis, the transport sector and household mobility are at the heart of territorial transition issues. In response to these challenges, in France and abroad, local authorities are increasingly using fare-free public transport, to encourage modal shift and also to meet a social objective of improving mobility for the most disadvantaged people. However, there is little scientific research to assess the real impact of this measure. This paper analyses the effect of the free weekend public transport measure launched in December 2022 by Clermont Auvergne Metropole. We use an econometric model comparing public transport ridership before and after the measure for the same public transport line and direction, at the same stop, during the same time period and on the same day of the weekend (Saturday or Sunday). Estimates are based on ticket validation data before the measure and manual counts after. In order to isolate the effect of the free transport measure, we introduce control variables relating to the main determinants of public transport ridership (e.g. public transport supply, fuel prices, weather data). We also introduce variables controlling for the potential effects of the Covid-19 crisis on household mobility. Our results show that free-fare public transport has led to an increase in weekend ridership of 47 % on the routes and stops observed. We also find that the measure effect is greater for the tramway line than for the bus lines. To our knowledge, this study is the first econometric analysis of the effect of free public transport applied to a French city.