Mobility Interaction Sim: A Scalable Experimental Research Platform for Mobility Research

This paper introduces Mobility Interaction Sim , a Unity-based experimental platform for human factors research on shared mobility environments where pedestrians, automated vehicles, micromobility riders, and delivery robots negotiate the same physical space. A single project compiles to two deployment targets: a Unity WebGL build for crowdsourced online studies and a native build for an in-laboratory virtual reality (VR) rig that incorporates a physical scooter handlebar, a head-mounted display, and wearable physiology. Scenarios, surveys, attention checks, and cognitive tasks are configured through the Unity Inspector, and a graphical Scene Graph manages condition assignment and counterbalancing. Behavioral and environmental states are logged as a time-stamped JSON stream from which standard kinematic measures such as time-to-collision, gap acceptance, and speed at the decision point can be derived. The platform is described together with three peer-reviewed case studies that employed it (two online, N = 208 and N = 200; one in-person VR, N = 50), as well as the interactive demonstration. The source code will be released under a non-commercial research license, with a browser-based demonstration and a source-access request form linked from the project page.