Taking a “free” ride: Where do we stand on free or low fare public transport and where do we go next?

Fare-free and low-fare public transport (FFPT) has shifted from a marginal idea to a visible policy in debates on transport equity, climate mitigation and cost-of-living relief. This paper reviews over 150 studies on FFPT and deep fare reductions, identified through a PRISMA-informed search of databases and grey literature. The review spans decades and covers empirical evaluations, theoretical work and policy analyses from Europe, North America, South America, Asia and Oceania. This review paper broadly addresses the main positive impacts of FFPT; key constraining factors; which groups benefit most, and under which conditions; and identifies research gaps. Across contexts, FFPT has been found to increase ridership and improve accessibility, particularly for low-income users, students and older adults, and can strengthen social inclusion and supports framing public transport as a public good. Evidence of substantial, durable modal shift from private cars, or of large emissions reductions, is limited and context dependent. Financial sustainability, capacity pressures and unintended social effects are recurrent challenges. The few studies estimating fare elasticities find that public transport demand is price-inelastic, so pricing is only one lever shaping travel behaviour. Persistent gaps include scarce longitudinal analyses, limited environmental measurement, regional bias towards Europe and North America, weak intersectional equity perspectives and incomplete understanding of how fare reform interacts with transport, land-use and welfare systems. Overall, FFPT improves accessibility and social equity, but its environmental and behavioural impacts are modest unless combined with broader strategies of service enhancement, demand management and integrated urban planning in diverse urban contexts.