Renewable energy sources in transport (RES-T) are crucial for mitigating climate change. As transport is currently almost entirely dependent on conventional fuels and, as such, has a significant share in global emissions, the transition to RES-T is an important aspect of broader climate policy. This transition requires changes in three dimensions: the vehicle fleet, energy infrastructure and energy carriers. The required changes depend on the technology pathway: battery-electric, hydrogen or biofuels. This study investigates the main barriers to each RES-T pathway and for all three dimensions, assesses individual policy instruments and defines an overall policy strategy to overcome these barriers. The main focus is on urban road transport.