determining, by a primary planner of an autonomous vehicle, a first action for the autonomous vehicle using a first process;

determining, by a fallback planner of the autonomous vehicle independent of the primary planner, an alternative action for the autonomous vehicle using a second process nonoverlapping with the first process, wherein the alternative action includes at least stopping the autonomous vehicle;

sending, by a multiplexer of a common control system of the autonomous vehicle, an indication of the alternative action for actuators to use to cause the autonomous vehicle to navigate in response to a faulty condition associated with the primary planner, wherein the faulty condition is the primary planner failing to predict a trajectory for other traffic participants in an environment of the autonomous vehicle; and

computing, by the fallback planner, a collision-free path for the autonomous vehicle responsive to a determination of an area at which the autonomous vehicle stopped after performing the alternative action fails to satisfy one or more area criteria.