Mobilizing transport justice: a sufficientarian optimization framework for intermodal mobility systems

Most applied research on transport justice focuses on evaluating existing systems, while transport planning typically relies on utilitarian objectives such as minimizing average travel time, without accounting for fairness. This paper starts to bridge this gap by applying different principles of justice to the operational planning of transport systems. We use an intermodal Autonomous Mobility-on-Demand system—centrally controlled self-driving vehicles cooperating with public transit and active modes—as a case study to improve conditions for users without access to private cars. We define and compare justice metrics that differ in both their distributive principle and the good of concern: utilitarianism applied to travel time, and sufficientarianism applied to either travel time or accessibility. A real-world case study in Eindhoven, the Netherlands, shows that these principles lead to different planning outcomes, highlighting the need for a broader debate on their implications. The results underscore the value of transdisciplinary and conceptually informed approaches to transport planning and system optimization.