PLANNING SYSTEM FOR SPEED LIMIT CHANGES FOR AUTONOMOUS VEHICLES

In one embodiment, a speed planning system receives speed limit information for an autonomous driving vehicle (ADV), where the speed limit information includes a change in road speed limit for a current road of the ADV. The system determines a tapered speed limit corresponding to the current road based on the speed limit information, where the tapered speed limit correspond to a gradual speed reduction from a first road speed limit to a second road speed limit. The system determines a cost function based on the tapered speed limit and the first and second road speed limits. The system generates a number of trajectory candidates based on the cost function. The system selects a trajectory based on the trajectory candidates to control the ADV using the selected trajectory.