Purpose: The purpose of this study is to assess the impact of rivalry and excludability in transport systems on the positive external effects important for the functioning of a large private university in Wroclaw (Poland). In the context of campus sustainability, policy implications supporting sustainable transport are discussed. Design/methodology/approach: Four research questions were formulated, which were tested by way of questionnaire research among students of the Bachelor and Engineer Programmes in Logistics and taking part in the course Transport Economics at the WSB University in Wroclaw (Poland). Findings: Car use seems to be the most important for the positive transport externalities enabling the functioning of the university. Levels of rivalry and excludability did not have a significant impact on the levels of external transport benefits or the transport behaviour of students. To sustain/enhance the levels of positive external effects of transport and stimulate sustainable commuting, the university should support the development of alternative modes of transport, by improving transport infrastructure on the campus, and develop cooperation with the Wroclaw municipality to develop synergies between their transport policy goals. Research limitations/implications: The research should be interpreted with care, as it is a case study of one large private university in Poland. Further research should be conducted among different private and public universities that are characterised by different levels of accessibility (location, development of infrastructure). The case study is based on students' transport behaviour, not considering transport behaviour of academic and non-academic workers, which could function as a role mode. Practical implications: Policy aiming at banning cars is likely to be unsuccessful and/or could lead to a decrease in positive externalities in a short term. For this reason, more attention should be given to marketing and promotion of more sustainable means of transport, including e.g. better information on the possibilities of reaching the campus by train or urban public transport, facilitations for non-motorised students and improvements in cycling and walking infrastructure. To support campus sustainability in the field of transport, stronger cooperation with local administration is needed to undertake joint, consistent actions aimed at sharing and supporting the idea of sustainable commuting among students. Originality/value: While many activities for supporting campus sustainability focus on reducing negative environmental externalities, positive externalities are not so often considered. In this context, the levels of rivalry and excludability can become an indicator of the contribution of transport systems to social and economic sustainability.