Figure 2 is a cross-section A-A from Fig 1 and shows the stacked helix effect. The layout consists of seven selves, each thirteen inches wide. Track on the first lap starts on the first shelf and goes around the room staying on the front (side nearest the operator). After one lap the track has gained four inches in elevation and jumps to the back of the first shelf using a "flyover" as discussed in the Flyover Section. The track goes around the room for the second lap but stays on the back side of the shelf. Generally there is limited operational potential on this lap. Switching, uncoupling and the like are done on the first lap where there is adequate room for the operator's hand. Finally, at the end of the second lap, the track jumps to the front of the third lap using the flyover. This cycle is repeated for each of the seven shelves. The odd number laps run on the front with operating opportunities and the even laps usually just gain distance and height.