a road user belonging to a category most at risk in traffic and generating little risk to other road users. Vulnerable road users are mainly those unprotected by an outside shield, namely pedestrians and two-wheelers, as they sustain a greater risk of injury in any collision against a vehicle and are therefore highly in need of protection against such collisions. Among these, pedestrians and cyclists are those most unlikely to inflict injury on any other road user, while motorised two-wheelers, with heavier machines and higher speeds, may present a danger to others.