Drive-In Racking: Lane Depth, Forklift Fit and the LIFO Trade-Off

These two get used interchangeably in sales material and they are not the same system. The difference is whether the lane is open at one end or both, and it changes the inventory behaviour completely.

So: is drive-in racking LIFO or FIFO? Drive-in is LIFO, unambiguously. You put the last pallet in at the front of the lane, and it is the one you take out first. Drive-through is the configuration people reach for when they need rotation, and it works — but you have paid back a chunk of the density you came for, because you now need clear aisle on both faces.

This matters for anything date-coded. Food and beverage operations with rolling production dates, or anything carrying a shelf-life obligation, will find LIFO fights them constantly. The workaround most facilities land on is a hybrid: drive-in for stable, high-volume, date-insensitive SKUs, and selective or flow racking for everything that rotates.

Here is the rule that no manufacturer product page will give you, because it depends on your inventory rather than their steel: lane depth should match the number of pallets you routinely hold of a single SKU — not the depth the building will physically allow.

The failure mode is honeycombing. Suppose you build six-deep lanes and a given SKU arrives four pallets at a time. Each lane now has two positions that cannot be filled, because putting a different SKU behind or in front of the first creates a lane you cannot unload in order. Those empty slots are paid-for, refrigerated, structurally supported air. Push that pattern across a hundred lanes and the 50% density gain you modelled quietly becomes 25%.

The reverse error is just as common. Two-deep lanes for a SKU that moves in twelve-pallet lots leaves you handling the same product across six lanes, multiplying travel and giving up most of the density benefit you built the system for.

So the design exercise is an inventory exercise, done before anyone quotes steel. Profile your SKUs by pallets held, not by SKU count. Cluster them. If most of your volume sits in a handful of SKUs held five or six pallets deep, you have an excellent drive-in candidate. If your volume is spread thinly across many SKUs at one or two pallets each, drive-in is the wrong system and no amount of clever lane sizing will fix that.

It is also worth sizing lanes against your replenishment rhythm rather than your peak. A lane that only fills completely in October is a lane that honeycombs for eleven months. Where your SKU depths vary widely, mixed lane depths in the same installation are normal and usually cheaper than forcing one depth on everything. For very deep, high-turn product, pallet flow racking handles depth without sending a truck into the lane at all, and for long or awkward loads that will never palletise well, cantilever racking arm capacities are the relevant constraint instead of lane depth.

A rack manufacturer sells you the lane. Nobody in that transaction necessarily checks whether your trucks can work inside it. This is where drive-in installations most often disappoint, and it is the part we get called about after the steel is up.

Four things decide it. Overall width: the truck plus its load has to pass between lane uprights with real clearance, not nominal clearance, because an operator reversing 20 feet out of a lane will not hold a two-inch margin. Free lift: the forks must rise to the upper rail level without the mast extending above the lane’s top rail, or the mast fouls the structure. Trucks with limited free lift can physically only serve the bottom rail level. Mast and overhead guard height: the whole truck has to clear the lane entry and any rail above it. Load backrest and fork length: placing a pallet on rails deep in a lane is a different task from setting it on a beam at the aisle face.

Then there is the operator. Driving into a steel tunnel, placing a load on rails you cannot see well, and reversing out straight is a genuinely harder skill than aisle work. Facilities that run drive-in successfully train specifically for it and keep a smaller, more experienced pool on those trucks. Facilities that do not will pay for it in rack repair. If you are still deciding between truck types for a high-density layout, the differences in reach truck versus forklift capability are the right starting point, and our notes on counterbalance forklift capacities cover why a standard sit-down truck’s dimensions often rule it out of lane work.

In selective racking, the uprights sit beside the aisle and get clipped occasionally. In drive-in racking, the uprights line the road. Every entry and every reverse is a truck and a load moving within inches of structure that is holding several tons above it. Damage is not an anomaly here; it is a running cost.

It is also more consequential. A drive-in bay depends on its frames, its rails and — critically — its cross-aisle ties and bracing to stand up. ANSI MH16.1-2023, the Rack Manufacturers Institute standard for industrial steel storage racks, puts clear obligations on the rack owner, including inspection at intervals no longer than twelve months with findings documented. The RMI guidelines on damaged rack are the reference for deciding whether a bent component gets repaired or replaced — and they are worth reading before someone in your facility decides a dented upright looks fine.

Practically, in drive-in bays: inspect more often than annually, treat missing beam locking pins, cross-aisle ties and bracing as immediate faults rather than housekeeping, fit lane-entry guards and floor-mounted guide rails as part of the original installation rather than as a later retrofit, and unload a damaged lane before assessing it. Our guides on protecting racking uprights and the signs your racking may fail apply with extra force in high-density bays, where a single compromised frame can take more of the system with it.

One more California-specific note: racking is a permitted structure in most jurisdictions here, and seismic requirements shape the frame and anchorage design. That is not a corner to cut on a drive-in system, where the structure is doing more work and taking more hits.

Drive-in is the cheapest high-density system per pallet position, and sometimes that makes it the wrong one. The alternatives keep the truck in the aisle and let the pallets do the moving.

The honest summary: if your product is date-insensitive, moves in consistent multi-pallet lots, and the building is expensive, drive-in earns its place. If you need rotation, or your SKU depths are irregular, or you have a history of rack strikes, the extra capital for push-back or pallet flow usually comes back in avoided damage and recovered selectivity.

We design and supply all three, and we also service the trucks that work in them — which means we have no reason to talk you into the densest option on the page. Bring us a SKU profile and a building drawing and we will tell you which of these actually fits.