Joschka Flintz, Stefanie Gaebler, Viktoria Kleinschmidt (p), Felix Roesel

Frank van Oort

Car ownership and use are major contributors to environmental and climate-related issues. Understanding how improvements in public transport infrastructure influence car dependency is therefore crucial for developing sustainable transport policies. This study investigates the impact of railway station openings on private car ownership in Germany between 2010 and 2022. Exploiting a quasi-experimental setting with the staggered opening of 170 new railway stations, we use a difference-in-differences design to estimate causal effects. Our analysis is based on geocoded administrative data on vehicle registrations at the one-square-kilometre level. For identification, we compare areas around newly opened stations to a control group of potential station locations where stations have been proposed but not yet realised. We find that the number of car registrations per household declines by between 4 and 5.5 per cent around newly opened stations. Event study estimates reveal that this effect emerges with a delay of two to three years, suggesting that rail services must first become established and integrated into travel routines before affecting car ownership decisions. Further analysis shows that these effects do not differ significantly between urban and rural areas. We also find no evidence of changes in the characteristics of registered vehicles in response to the new stations. Our findings suggest that improving rail access could play a meaningful role within a broader portfolio of measures aimed at reducing car dependency and promoting sustainable mobility.

Anastasia Patsouri (p), Fabio De Oliveira Paula

Frank van Oort

Innovation and entrepreneurship are critical drivers of sustainable development, particularly in the context of university startup ecosystems. As global challenges such as climate change, social inequality, and economic instability intensify, the role of entrepreneurial ecosystems in fostering sustainable innovation has become a key area of academic inquiry. University startups, as hubs of knowledge-intensive entrepreneurship, serve as catalysts for economic growth while also addressing pressing environmental and social issues through novel business models and technological advancements. However, the extent to which these startups integrate sustainability into their core strategies remains an open question.
This study investigates the preliminary impact of academic entrepreneurship on sustainable development by analyzing Brazilian university startups, from Rio de Janeiro and São Paulo. Using a multiple case study approach, it examines how these ventures navigate sustainability as a whole but also the intersection market demands, environmental responsibility and their ecosystem dynamics. Through structured interviews and secondary data analysis, this research explores their business models, value propositions, and strategies for aligning with the United Nations’ Sustainable Development Goals (SDGs). Additionally, it assesses the role of entrepreneurial ecosystems—including incubators, universities, investors, and policymakers—in supporting sustainable innovation. In total 30 interviews are conducted; 25 with startup founders and 5 with incubator managers from the 5 different university incubators.
Despite the growing emphasis on sustainability-oriented entrepreneurship, several academic debates persist. How do resource constraints affect the ability of startups to implement sustainable practices? To what extent do universities and incubators provide the necessary support for sustainability-driven ventures? How can impact measurement frameworks be standardised to assess the economic, social, and environmental contributions of startups? Furthermore, the role of government policies and financial incentives in shaping sustainable entrepreneurship remains a contested area, on the effectiveness of various regulatory approaches.
This research contributes to the broader discourse by highlighting the motivations, challenges, and strategic decisions of university startups operating within a sustainability framework. It underscores the need for stronger institutional support, multi-stakeholder collaboration, and policy interventions to enhance the role of academic entrepreneurship in driving long-term sustainable development. By addressing these open academic questions, this study aims to advance theoretical and practical insights into the evolving landscape of sustainable innovation and entrepreneurial ecosystems.