We examine the law of steering - a quantitative model of human movement time in relation to path width and length previously established in hand drawing movement - in a VR locomotion paradigm. Participants drove a simulated vehicle in a virtual environment on paths whose shape and width were manipulated. Results showed that the law of steering also applies to locomotion. Participants? mean trial completion times linearly correlated (r² between 0.985 and 0.999) with an index of difficulty quantified as path distance to width ratio for the straight and circular paths used in this experiment. Their average mean and maximum speed was linearly proportional to path width. Such human performance regularity provides a quantitative tool for 3D human machine interface design and evaluation.