An apparatus for sorting a plurality of items, comprising: a plurality of sort destinations; a plurality of delivery vehicles for delivering items to the sort destinations, wherein each vehicle comprises an on-board motor for driving the vehicle; a loading station for loading items onto the delivery vehicles; a track system for guiding the delivery vehicles to the sort destinations, characterized in that the apparatus comprises: a plurality of first rail sections (135, 140) extending in a first direction wherein the first direction is generally horizontal; a plurality of second rail sections extending in a second direction, generally orthogonal to the first direction, wherein the second direction is generally vertical; a plurality of intersections where one of the first sections intersects with one of the second sections, wherein the intersections provide a continuous path between a path of travel in the first direction along one of the first rail sections to a path of travel in the second direction along one of the second rail sections; and means for directing the delivery vehicles (180, 350), wherein the means is operable to separately direct each delivery vehicle to one of the sort destinations; wherein the delivery vehicles comprise means (222, 224) for engaging the track system to maintain the orientation of the vehicle relative to the horizon as the vehicle moves between one of the first rail sections and one of the second rail sections. a plurality of sort destinations; a plurality of delivery vehicles for delivering items to the sort destinations, wherein each vehicle comprises an on-board motor for driving the vehicle; a loading station for loading items onto the delivery vehicles; a track system for guiding the delivery vehicles to the sort destinations, characterized in that the apparatus comprises: a plurality of first rail sections (135, 140) extending in a first direction wherein the first direction is generally horizontal; a plurality of second rail sections extending in a second direction, generally orthogonal to the first direction, wherein the second direction is generally vertical; a plurality of intersections where one of the first sections intersects with one of the second sections, wherein the intersections provide a continuous path between a path of travel in the first direction along one of the first rail sections to a path of travel in the second direction along one of the second rail sections; and means for directing the delivery vehicles (180, 350), wherein the means is operable to separately direct each delivery vehicle to one of the sort destinations; wherein the delivery vehicles comprise means (222, 224) for engaging the track system to maintain the orientation of the vehicle relative to the horizon as the vehicle moves between one of the first rail sections and one of the second rail sections. a plurality of first rail sections (135, 140) extending in a first direction wherein the first direction is generally horizontal; a plurality of second rail sections extending in a second direction, generally orthogonal to the first direction, wherein the second direction is generally vertical; a plurality of intersections where one of the first sections intersects with one of the second sections, wherein the intersections provide a continuous path between a path of travel in the first direction along one of the first rail sections to a path of travel in the second direction along one of the second rail sections; and means for directing the delivery vehicles (180, 350), wherein the means is operable to separately direct each delivery vehicle to one of the sort destinations; wherein the delivery vehicles comprise means (222, 224) for engaging the track system to maintain the orientation of the vehicle relative to the horizon as the vehicle moves between one of the first rail sections and one of the second rail sections.