Erratum: Re-examining fare-free public transport for greater inclusivity (Transportation Research Interdisciplinary Perspectives (2025) 31, (S2590198225001332), (10.1016/j.trip.2025.101454))

Abstract Fare-free public transport (FFPT) schemes – in which public transport costs are paid through means other than individual fares – are gaining traction in improving public transport efficiency and accessibility. However, there is a lack of research about how these programs impact socio-economic, sexual orientation, and gender identity perspectives. While many studies collect demographic or economic data about public transport riders, they often fail to effectively utilize the data to its potential for research. A review of 146 studies reveals significant intellectual gaps, including a lack of consideration for demographic characteristics of transport users, missed opportunities to incorporate socio-economic and sexual orientation and gender identity perspectives, and geographical imbalances in research. The review suggests the need for more comprehensive, equitable approaches to FFPT research that supports the development of inclusive public transport policies. Keywords: Access; Discrimination; Equity; Fare-free public transport; Gender difference; Public transport. Public transport provides access and mobility to citizens, residents, and visitors anywhere it is available, and public transport also contributes to economic prosperity in its host communities. Public transport also plays a pivotal role in improving social equity by mitigating barriers that limit certain groups’ ability to participate in everyday life (Allen and Farber, 2020). A well-functioning public transport system is thus essential for vulnerable groups who are dependent on it for access and mobility. Enhancing accessibility to various places by public transport can reduce vulnerability for these groups and mitigate transport-induced social exclusion (Lucas et al., 2016). Consequently, research should focus on equity in the distribution of public transport benefits to minimalize gaps in accessibility levels among various socio-economic, racial, and ethnic groups to foster more inclusive societies (Foth et al., 2013; Sträuli and Kębłowski, 2022). Unsurprisingly, policymakers and managers of public transport systems continually reinvent public transport to improve its efficiency and cost-effectiveness and its ability to provide high-quality access and mobility for the traveling public. One particular reform—sometimes viewed controversially—gaining renewed traction in recent years (Kębłowski, 2020) is the establishment of fare-free public transport (FFPT) schemes in which passengers do not pay cash fares to ride public transport vehicles; in lieu of cash fares, public transport service is funded through other means. We explore in this article how FFPT research addresses socio-economic and demographic characteristics of riders who may (or may not) benefit from fare-free public transport to shed more light on how FFPT challenges social exclusion. Our interest in this topic emanates from the growing attention on FFPT among scholars and transport practitioners, since the list of municipalities and public transport systems implementing fare-free schemes is expanding globally. Currently there are more than 300 localities¹ that have launched full-coverage FFPT² compared to 27 FFPT programs identified prior to 2000 (Kębłowski, 2020). Geographically, the fare-free public transport schemes are not limited only to North America and Western Europe, as the most rapid development of new programs is currently happening in Brazil (Pereira et al., 2023a,b) and Poland (Štraub et al., 2023), suggesting that FFPT is not limited to wealthy societies. Scholarly research about FFPT covers diverse topics, from financial impacts (Perone, 2002; Tomeš et al., 2022; Zakaria et al., 2024) and political motivations (Carr and Hesse, 2020; van Goeverden et al., 2006; Kȩbłowski et al., 2019; Prince, 2018; Schein, 2011) to practical aims like improving mobility, reducing automobile use or generating public transport ridership (Brand, 2008; Cats et al., 2017; Cools et al., 2016; Dai et al., 2021; Fiedeń and Štraub, 2023; Storchmann, 2003; Štraub, 2020, 2023b; Volinski, 2012). The body of research, however, lacks a unified consensus about optimal implementation contexts. Most studies focus on single localities, with few comparative analyses (Delevoye et al., 2022; Kębłowski et al., 2023; Pereira et al., 2023a,b; Štraub et al., 2023). Additionally, many studies emphasize policy outcomes without fully exploring the context of policy establishment (Marsden and Reardon, 2017; Dudley and Richardson, 2000; Siren and Sørensen, 2015). Recent work by Kębłowski (2023a) and (2023b) suggests new approaches to understand where and under which conditions FFPT programs could thrive. While this study focuses on socio-economic and demographic aspects of FFPT programs, we recognize FFPT's role in addressing transport externalities from automobile use – those negative impacts that vehicle users impose on others without bearing the costs, such as pollution, congestion, and accidents. Štraub and Jaroš (2019) and Fearnley (2013) identify FFPT as one of several instruments for reducing externalities, though Fearnley notes that despite substantial ridership increases, effects on automobile traffic are often marginal with short-term duration (see also Cats et al., 2014, 2017). This aligns with Cavallaro et al.’s (2024) observation that increased travel demand can actually worsen certain externalities, particularly congestion and accident costs, even as other externalities like air pollution may decrease. Strommer et al. (2023) suggests that public transport itself creates negative externalities through passenger crowding, causing a discomfort that complicates the setting of fares and public transport subsidy rates that should reflect reduced automobile use and potential discomfort from crowding. Yang et al. (2022) find that information provision influences mode choice behavior, impacting FFPT's ability to leverage positive externalities. These findings suggest FFPT may be most effective when implemented within a comprehensive transport policy framework including both supportive and restrictive measures (Štraub and Jaroš, 2019; Kębłowski, 2020). Although there is a rich body of research that reveals how FFPT affects public transport ridership, automobile use, and individual mobility strategies, there is a scarcity of research addressing the effects of applying various socio-economic and sex or gender perspectives despite the consensus that FFPT is critical for helping vulnerable members of society in their ability to reach important destinations for daily life. In this literature review, we address this gap by providing a comprehensive review of how gender- and socio-economic-inclusive lenses are infused in the research agenda of fare-free public policy. Our aim is to critically examine the current state of FFPT research through socio-economic and gender-inclusive perspectives. Specifically, we address these questions: (1) How thoroughly do existing FFPT studies incorporate the perspectives of vulnerable and marginalized societal groups? (2) What gaps exists in our understanding of how FFPT affects different socio-economic and gender groups? (3) To what extent do current research approaches reveal the potential of FFPT to mitigate social exclusion and improve mobility for marginalized populations? Addressing these questions allows us to explore, in a systematic way, how non-dominant groups are accommodated in FFPT and how the experience of non-dominant groups in alternative fare payment schemes is captured in scholarly research. In doing so, we hope to further, in helpful ways, an understanding of the synergy between research and practice and advance research about FFPT. In the next section, we explain how we execute the literature review reported in this article. Following that, we present the results of our thorough analysis of published literature, and we focus on the inclusion of non-dominant groups in FFPT studies. Finally, we present concluding insights from our research and we emphasize missed opportunities for inclusion of non-dominant groups, leading to a discussion of avenues for further research. The FFPT topic has gained traction especially during the last two decades (1973–2000: 21 articles versus 2001–2024: 124 articles) which goes in hand with an increasing number of municipalities and public transport systems that opt for fare abolition. Although FFPT has been systematically studied since the 1970s, the topic still represents a niche field of transport research. Most studies tend to focus on individual FFPT programs, with only a handful of studies and reports that summarize FFPT from various viewpoints combining research and practice (Baum, 1973; Scheiner and Starling, 1974; Perone, 2002; Fearnley, 2013; Kębłowski, 2020; King and Taylor, 2023) and no reviews provide an overview of existing knowledge and trends in FFPT studies. We address this gap in FFPT research by undertaking a narrative literature review. This approach allows us to generate a qualitative summary of relevant literature, allowing flexibility in terms of selected studies that adopt various methodologies or address various research questions (Baumeister, 2013; Gregory and Robert Denniss, 2018; Pautasso, 2013, 2019). Our aim is to explore how fare-free public transport policy research incorporates gender and socioeconomic factors, and we believe that a narrative literature review is the most suitable method for this purpose due to its flexibility. Unlike systematic reviews, which emphasize methodological consistency and strict inclusion criteria, a narrative literature review allows us to capture the complex intersectional perspectives related to gender and socioeconomic issues within the multifaceted and interdisciplinary nature of FFPT research. To arrive at the final list of studies included in this review, several steps are performed. First, using key search terms (‘FFPT’, ‘fare-free’ AND ‘public transport’,³ ‘zero fares’ AND ‘public transport’, ‘fare free’ AND ‘public transport’, ‘free fare’ AND ‘public transport’, ‘pre-paid fares’ AND ‘public transport’), we access three important databases: Scopus, Web of Science, and TRID databases. The search returned 580 studies in total, distributed as follows: Scopus (126), Web of Science (249), TRID (205). Second, to ensure that only relevant studies are included, we omitted duplicates, non-English publications, and articles not related to transport, geography, or social science (e.g., medical studies). After this step, 113 publications remain for further assessment. Third, we supplement this group with relevant studies that match the selection criteria and are based on our own experiences with FFPT literature but are not indexed in the databases. The literature selection is not restricted to a specific period of time. We include all relevant studies from the earliest published FFPT research in the 1970s through October 2024. This was done intentionally so that we could capture the widest number of relevant studies in the life of FFPT programs worldwide. In the end, 146 publications are identified for our study, in which we explore how non-dominant groups are included in FFPT programs and whether the researchers that evaluated FFPT programs paid special attention to how non-dominant groups use FFPT services and how FFPT programs achieve their stated outcomes. These works can be divided into three categories:.