In one embodiment, an storage module has first and second guide rails that are spaced from one another along a lateral direction. Each guiderail has an upper track and a lower track spaced from one another along a vertical direction, and first and second connecting tracks that connect the upper track to the lower track at first and second ends, respectively. A plurality of inventory carriers that are supported between the guiderails and are arranged end-to-end along the upper and lower tracks. A drivetrain drives the carriers to translate along the upper and lower tracks at a first speed, and drives the carriers to translate along the connecting tracks at a second speed, faster than the first speed. Increasing the speed of the carriers at the connecting tracks can prevent the carriers from colliding with one another when transitioning between the upper track and the lower track.