I. Introduction
Urban light transport (ULTRA; see Fig. 1) is a personal rapid transit (PRT) vehicle developed by Advanced Transport Systems Ltd. [1]. It is an unmanned steer-by-wire electric vehicle capable of carrying a 500-kg payload at speeds up to 40 km/h. ULTRA aims to improve the transportation needs of a busy city or other public space (e.g., Heathrow Airport Terminal 5 in this case) with minimal environmental impact while providing a comfortable flexible travel solution for up to four passengers with luggage.
ULTRA PRT vehicle [1].