Walking consumes a large share of a picker’s shift in a static shelving layout, and that share grows as the product range expands. Every new line added to the pick face pushes the other lines further apart, so the distance between picks increases even when order volumes stay flat. The picker is busy. The picker is not picking.
A second cost sits alongside the first. Static shelving presents one carton face per location, so a fast-moving line runs out mid-shift and stops the pick until someone restocks it. Carton live storage addresses both problems by changing how stock presents itself to the person picking.
How gravity-fed carton picking works
Carton live storage is a racking system in which cartons load onto inclined lanes at the rear and travel forward under their own weight to a pick face at the front. The system is also sold as carton flow racking and gravity flow racking. All three names describe the same arrangement.
The physical elements are straightforward. Each lane sits at a gradient calculated for the product it carries. Roller track or skate wheel rail runs the length of the lane to provide low friction. Lane dividers keep adjacent product lines separated so cartons do not drift sideways. Brake rollers can control speed where heavier cartons would otherwise arrive at the front too fast, and entry guides at the loading end keep cartons square as they enter.
No power is required. Gravity does the work, which means no motors, no control system and no ongoing energy cost. When a picker removes the front carton, the one behind it moves forward to take its place automatically. That single behaviour is the operational core of the entire system.
Where the efficiency gain comes from
The gain comes from six separate changes to how picking works, and understanding each one lets you assess the system against your own operation rather than against a headline claim.
| Source of gain | What changes operationally |
| Reduced travel distance | Many product lines compress into a small pick face area, shortening the walk between picks |
| Higher pick face density | Every lane presents a live pick face, so more lines sit within arm’s reach of one position |
| Ergonomic pick height | Lanes concentrate into the comfortable range between knee and shoulder height, reducing bending and reaching |
| Automatic stock presentation | The next carton arrives at the pick face without a picker or replenisher intervening |
| Separated pick and replenishment aisles | Restocking happens from the rear, so it does not interrupt or congest the pick aisle |
| Enforced stock rotation | Cartons leave in the order they were loaded, so first in first out rotation happens by design rather than by discipline |
The size of the gain depends on your current layout, your order profile and the proportion of your range that suits the system. An operation picking most of its lines from a concentrated set of fast movers gains far more than one picking evenly across a long tail.
Which stock suits carton live storage
The system works within a defined band, and being clear about that band saves an expensive mistake. Suitable cartons are within a workable size and weight range, have a firm flat base that slides or rolls predictably, and move at a rate high enough to justify occupying a dedicated lane.
Several categories do not suit it. Slow-moving lines tie up a lane for weeks and deliver no return on the space. Very light cartons stall on the track because there is insufficient weight to overcome friction. Soft or irregular packaging such as polybags, sacks and shrink-wrapped bundles catches on rollers and does not flow reliably. An operation holding a large number of low-velocity stock keeping units generally sees better results from conventional longspan shelving for most of the range, with carton live storage applied only to the fastest lines.
A design trade-off runs through every installation. Lane depth and lane count compete for the same floor area, so a system tuned to hold many product lines carries less buffer stock per line and needs replenishing more often. Velocity analysis of your order lines identifies which stock keeping units earn a lane, and the answer usually covers a smaller share of the range than expected.
Flow behaviour is tested with your actual product. Carton base material, weight, dimensions and surface finish all affect how a carton travels, and a specification sheet does not predict how a particular package behaves on a particular track.
Layout and building requirements
Rear access is the requirement most operations underestimate. Replenishing from behind the pick face is what removes aisle congestion, and it usually means committing a separate aisle to a task that previously shared space with picking.
- Rear replenishment access, typically a dedicated aisle behind the pick face
- Sufficient depth for the lane length required, since lane depth sets how many cartons buffer before restocking
- Clear height for the lane levels planned, including the loading level above the pick face
- A floor capable of carrying the loaded system, with anchoring assessed as for any racking installation
- Lighting positioned for the new pick face rather than for the previous layout
- Space upstream and downstream for the pick trolley, conveyor or dispatch flow the system feeds
Carton live storage integrates with pallet racking above or behind the pick module, which holds bulk reserve stock close to the point of replenishment. The same principle applies when working within a tight building, where the priorities set out for maximising space in a small warehouse still govern the overall layout.
Replenishment and operational design
Carton live storage changes the replenishment task rather than removing it. Replenishers load lanes from the rear on a schedule driven by lane depletion, which decouples restocking from picking entirely. The congestion that occurs when a forklift or trolley blocks a pick aisle disappears, because the two activities no longer share space.
A warehouse management system is not strictly required, though lane-level location mapping makes replenishment planning considerably more reliable. Knowing which lanes are approaching empty allows restocking to happen ahead of the pick rather than in response to a stoppage.
Batch traceability benefits from the flow arrangement without being solved by it. First in first out movement supports batch and expiry discipline because cartons physically cannot leave out of sequence, which matters for pharmaceutical, medical and short shelf life stock. The recording of batch numbers still sits with your system of record.
How carton live storage compares with the alternatives
The comparison below covers the three systems most operations weigh against each other when reviewing a pick face layout.
| System | Access method | Stock rotation | Pick face density | Replenishment | Best suited to |
| Static shelving | Direct from a fixed shelf | Manual discipline required | One face per location | Same aisle as picking | Slow to medium movers across a mixed range |
| Carton live storage | From a live pick face fed by gravity | First in first out by design | Many lines within one pick position | Separate rear aisle | Fast-moving cartons within a defined size and weight band |
| Pallet live storage | Full pallet from a live lane fed by gravity | First in first out by design | One pallet face per lane | Separate rear aisle by forklift | Fast-moving full pallet lines |
Most warehouses end up running a combination rather than choosing one. The fastest lines justify carton live storage, the long tail stays on shelving, and reserve stock sits in pallet racking above.
Safety and compliance considerations
Racking supporting carton live storage must be designed and installed to AS/NZS 4084, the Australian and New Zealand standard for steel storage racking, with load application drawings supplied and load signage displayed at each bay. Lane load limits deserve attention because cartons accumulate along the full lane length, so a lane loaded to capacity carries considerably more than the pick face suggests.
System-specific safety points sit alongside the standard racking requirements. Entry guides and end stops prevent cartons overrunning at either end of the lane. Replenishment at the upper levels involves manual handling considerations that the layout should address at design stage rather than through procedure.
Periodic storage system inspection covers track and roller condition, lane divider integrity, and anchor condition, since worn or damaged track produces stalling and inconsistent flow before it produces a safety issue. Under New Zealand health and safety law, the business operating the site holds a duty to manage the risks its storage systems create, and that duty runs continuously.
Working out whether it fits your operation
The answer comes from your order data rather than from the equipment specification. Five inputs determine it: the proportion of order lines drawn from your fastest-moving stock keeping units, the dimensions and weights of the cartons on those lines, your current pick rates and travel distances, your available floor area and clear height, and the rear access you can commit to replenishment.
A design assessment converts those inputs into a lane count, a lane depth and a projected pick face layout, which is the point at which the investment can be evaluated properly. Storepro has worked with third party logistics provider Hobbs Global for more than ten years reconfiguring racking as client stock profiles change, which is the same exercise applied to a picking layout. Talk to a racking specialist about a pick face layout built around your fastest-moving lines.