A subject vehicle in traffic can detect a second vehicle using sensors that measure motions of the second vehicle, and thereby determine one or more future trajectories of the second vehicle, and thereby determine whether a collision between the subject and second vehicles is imminent. The subject vehicle can calculate one or more sequences of actions, each action comprising an acceleration, a deceleration, and/or a steering action of the subject vehicle. The subject vehicle can also calculate whether any of the one or more sequences of actions can avoid the imminent collision, and also calculate an expected harm of the imminent collision according to each of the one or more sequences of actions. The subject vehicle can then autonomously select and implement a particular sequence of actions that is calculated to avoid the imminent collision or to minimize the harm of the imminent collision.