Proper drive-in and drive-thru operating sequence for safe operations and pallet rack organization.
Learn more about Drive-in and Drive-thru systems
For some people, ‘drive-ins’ and ‘drive-thrus’ bring back feelings of nostalgia, of catching a great movie in your car or a quick meal at your favorite burger joint, but these concepts take on a completely different meaning in a warehouse setting.
When space is a concern, many warehouse managers choose drive-in and drive-thru racking systems as opposed to conventional selective pallet racking systems to improve pallet rack organization. These racking systems are a high-density storage solution that optimize warehouse space by allowing many pallets to be stored in a concentrated area. Yet, they are as vulnerable to vibrations and damage from impacts as more standard racks. For each of these systems, a specific loading and unloading sequence is recommended for safe operation. These systems differ in their operation, as lift truck drivers should never drive directly under a pallet when loading/unloading both drive-in and drive-thru systems. It is important to follow a recommended storage strategy whenever using these systems to maintain the integrity of the rack as well as the safety of all warehouse employees.
Loading sequence for Drive-in systems: Last In, First Out (LIFO)
Drive-in systems are accessible only from one end. Due to this single point of entry, products in a drive-in system must be loaded and unloaded in a “Last-In, First-Out” manner (LIFO).
Drive-in loading/unloading sequence:
- Fork trucks first place a load on the first level at the back of the system
- The next load is then placed above the previous load until the lane is full
- The procedure is then repeated in the neighboring lane
- To unload the system, the loads should be removed in the reverse order
Loading sequence for Drive-thru systems
Drive-thru systems are similar to drive-in systems, but they are accessible from both ends. The two entry points allow for an alternate unloading sequence in comparison to drive-in systems.
Drive-thru loading/unloading sequence:
- Loading similar to drive-in system
- Unloading should begin with the uppermost load at either end of the drive-thru system
- The next load is then removed from under the previous load until the lane is empty
- The procedure is then repeated in the neighboring lane
Loading risks to consider
Drive-thru systems have limited down-aisle lateral stability as the uprights are only braced at the top and on the floor. They often rely on the pallets themselves to provide some lateral stability between these two supporting points. It is therefore essential not to load a bay and leave its neighboring bay empty, as this may contribute to the loaded bay’s width expanding into the empty bay. This “opening” effect causes the rails to be pushed further apart, potentially leading to pallets falling from their position.
Drive-in and drive-thru systems allow forklift trucks to drive into the racks. As the lift truck only has a narrow clearance on either side, it’s essential for drivers to be careful not to damage the rack components. The pallet type and their condition are also of concern. Pallets must be compatible with the rack system being used and should be checked for damage regularly.
A damaged or broken pallet shouldn't be used to store material in the racks.
Figure 1 – Example of a damaged pallet (source)
While drive-in and drive-thru systems may increase pallet rack organization and storage capacity of a warehouse, they must be used with caution. Just as you would follow the directions on parking signs when parking your car on a busy downtown street to avoid a costly ticket, make sure to follow the directions above when parking your pallet at the drive-in to avoid a costly mistake.
