PIARC: Impact of the Development of Active Transport Modes in Road Tunnels – Current Situation Report and Case Studies examines the growing integration of active transportation modes—such as pedestrians, cyclists, and other vulnerable road users—within road tunnel environments. As cities seek to improve mobility, accessibility, and emissions outcomes, tunnel owners and operators face new safety, design, and operational challenges when authorizing active modes in these confined facilities. This international report compiles and evaluates case studies from around the world, highlighting how tunnels are being constructed or retrofitted to safely accommodate active users through infrastructure adaptations, equipment upgrades, and revised operational procedures.

The document categorizes examples into four approaches: tunnels with safety galleries usable by active modes, tunnels with protected spaces for active users, tunnels with specific geometric or operational adaptations, and tunnels dedicated entirely to active mobility. Drawing on global expert contributions, the report outlines the state of practice and identifies key considerations for safety, risk management, and coordination with emergency services. It provides a foundation for future recommendations to guide decision-making by tunnel owners, designers, safety professionals, and transportation agencies considering active mode integration.