How much floor does the aisle take?
Much more than it seems, and it stores nothing.
In conventional racking, a large share of the floor is forklift traffic. Storing in depth cuts the aisles and gives that floor back to stock, without moving.
What it is
There are three solutions that differ in how the pallet reaches the back of the channel: the forklift drives in (drive-in), the new pallet pushes the previous one (push-back) or a motorised cart carries it (satellite cart). It can triple density and free up to 66% of the floor occupied today.
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The cost is always the same: less direct access to each position.
In practice
Instead of placing each pallet against an aisle, pallets are stored one behind the other inside the rack channel. You gain floor area and give up direct access.
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The variants are chosen after looking at the SKU mix, the turnover and the real clear height of the building.
What compact storage is: drive-in, push-back and pallet shuttle
Push-back: each load pushes the one before it
In push-back, every channel carries nested carts or rollers on inclined rails. The forklift places the pallet at the mouth of the channel and, as the next one comes in, the new pallet pushes the previous one towards the back; when one is removed, those remaining roll forward on their own by gravity.
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The forklift never enters the racking: it always works from the aisle, face on. That makes cycles faster than drive-in and sharply reduces the risk of impacts against the structure, which is where the hidden cost of a compact system usually sits. The trade-off is that the usable depth of each channel is shorter than in drive-in, and so is the final density. It also works in LIFO mode. It tends to suit operations with an intermediate number of references, each with enough volume to fill a whole channel, and operations with entry and exit peaks that punish handling times.
Pallet shuttle inside the channel: depth without the forklift entering
The pallet shuttle is a motorised cart that travels inside the channel, taking the pallet to the back and bringing it out again. The forklift only leaves it at the mouth of the channel and moves on to another task.
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Since nobody circulates inside the racking, channels can be designed far deeper than in drive-in without multiplying risk, and cycle times stop depending on operator skill. It is also the only one of the three variants that supports both logics: if loading and unloading happen at the same end it works as LIFO; if loading happens at one end and unloading at the opposite one, it works as FIFO, from first in, first out, meaning the first thing in is the first thing out, which is what goods with an expiry date require. It is likewise the variant best suited to cold storage: pallet shuttle systems operate down to −25 °C.
What changes in day-to-day operations
A compact system does not only change the racking: it changes how goods are located and counted. The unit of location stops being the individual position and becomes the channel, so the allocation rule has to be written down and respected, ideally supported by a warehouse management system, or WMS: the software that decides and records where each pallet goes.
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The fleet needs reviewing too, because each variant calls for a different type of forklift and mast height, and so does the floor, because flatness and permissible load condition how high the installation can go. The real gain does not appear on installation day, it appears once the channel rule is running steadily. That is why STOKA starts with a survey of the process and only then sizes the system.
Drive-in racking: when it fits and what it demands
In a drive-in system the racking forms continuous channels with no aisles in between, and the forklift drives inside the channel to deposit or retrieve the pallet.
It is the variant that delivers the most density, because almost all the built volume is taken up by goods rather than by circulation. In exchange it behaves like a stack of crates: the last pallet in is the first that can come out. That logic is called LIFO, from last in, first out, which in plain terms means the last thing in is the first thing out.
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It suits operations with few distinct product references and high volume of each one, because every channel is dedicated to a single reference and is filled and emptied as a block. It demands operational discipline: driving a forklift inside the racking calls for training, good visibility and upright protection. Channel depth, number of levels and profiles are defined during the site survey and delivered in the technical sheet of the diagnosis.
Five criteria for choosing between drive-in, push-back and pallet shuttle
We do not publish model-by-model specification tables: the detailed sheet comes with the assessment, sized against your operation. These are the criteria the choice is made on.
References against volume per reference
This is the criterion that weighs most. Few references with high volume of each one justify deep channels; many references with low volume of each waste the channel and end up creating gaps that nobody uses.
Turnover and expiry dates
If goods expire or demand strict batch traceability, you need FIFO, the first thing in is the first thing out. Drive-in and push-back work in LIFO; the pallet shuttle supports both logics depending on how the channel is configured.
Available clear height
Height defines how far you can densify: the ceiling is multiplying what conventional racking holds by up to 3 times. How much of that margin applies to you also depends on the load unit and the access you need. It is measured during the survey.
Floor, fleet and people
Floor flatness, permissible load, forklift type and the training level of the team define which variant is realistic. The further the forklift enters the racking, the more training and protection weigh on the decision.
Working temperature
If the warehouse or part of it is cold storage, the range conditions the solution. Pallet shuttle systems operate down to −25 °C, and automated systems with stacker cranes reach −30 °C. Outside those ranges the approach has to be reviewed.
When is a high-density system the wrong answer?
It does not pay if you need to reach any SKU at any moment.
With many SKUs and small orders, taking out one pallet means moving the ones in front, and that movement eats the floor gain. Nor if the product expires and the available configuration does not let the first in be the first out. And if volume per SKU does not fill a channel, a half-full channel takes up the whole space anyway.
Frequently asked questions
Can't find your question?Write to us and we reply within one business day.
Tell us about your case01Can high density be combined with conventional selective racking?
Yes, and in most warehouses that is exactly what happens. References with high volume and little variety go into deep channels, while those with wide variety and low volume stay in selective positions with direct access. Where the line between the two zones falls comes out of the turnover analysis in the survey.
02How long does an installation take?
The reference lead time STOKA works with is 3 to 4 months from the purchase order, covering manufacturing, importing, assembly and commissioning. The survey and the design come before that. If the floor or the fire protection system has to be reworked, that construction runs separately and is quoted apart.
03Is this better than moving to a larger warehouse?
That is a calculation to run with your own figures. As a reference, premium industrial rent in Greater Buenos Aires averages USD 7.33 per sq m per month, with the city of Buenos Aires at USD 14.52 and the Route 9 corridor at USD 5.59 (CBRE, Q2 2026). Densifying what you already have competes with that rent every month.
04What if we want to automate later on?
A compact layout is a natural step towards automation, because it settles the location rule and the channel logic before equipment is added. STOKA designs systems so that evolution stays possible, but does not recommend it by default: process first, robotics only where volume and repetition justify it.
Other systems
Let us put numberson your warehouse
Request the survey: STOKA measures clear height, floor, product mix and turnover, and delivers the diagnosis with the technical sheet of the solution that actually fits.