We describe a real-time model of terrain traversal by simulated human agents. Agent navigations includes a variety of simulated sensors, terrain reasoning with behavioral constraints, and detailed simulation of a variety of locomotion techniques. The path through the terrain is incrementally computed by a behavioral reasoning system configuring a behavioral feedback network. A number of sensors acquire information on object range, passageways, obstacles, terrain type, exposure to hostile agents, and so on. The behavioral reasoner weighs this information along with collision avoidance, cost, danger minimization, locomotion types, and other behaviors available to the agent and incrementally attempts to reach a goal location. Since the system is reactive, it can respond to moving obstacles, changing terrain, or unexpected events due to hostile agents or the effects of limited perception. A motor-level component provides general locomotion, including curved path walking and running that work in real-time with human figures.