Techniques for determining gaps for performing lane change operations are described. A first region in an environment of a vehicle can be determined. The first region can be associated with a first time period through which the vehicle is unable to travel and can correspond to a constraint space. A second region of the environment can be determined. The second region can be associated with a second time period and can correspond to a configuration space. A gap in the environment can be determined based on a portion of the configuration space that is exclusive of the constraint space. A trajectory can be determined based on the gap. The trajectory can be associated with performing a lane change operation and can be associated with a cost. The vehicle can be controlled to perform the lane change operation based at least in part on the trajectory and the cost.