Various technologies described herein pertain to a vertically stacked lidar assembly of an autonomous vehicle. The vertically stacked lidar assembly includes a first lidar sensor system configured to spin about an axis and a second lidar sensor system configured to spin about the axis. The first lidar sensor system is vertically stacked above the second lidar sensor system in the vertically stacked lidar assembly. Moreover, the first lidar sensor system and the second lidar sensor system are coaxially aligned. Redundancy is provided by the vertically stacked lidar assembly including the first lidar sensor system and the second lidar sensor system.