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One increasingly popular option is a very narrow aisle (VNA) pallet racking system. These high-density storage configurations could allow you to significantly increase your facility’s capacity without a costly expansion or relocation.
A very narrow aisle (VNA) system describes any pallet racking layout designed with narrower aisle widths than traditional wide-aisle storage. By reducing floorspace devoted to aisles and honoring rooms, warehouses can dramatically boost their total pallet positions and cubic storage capacity.
The defining characteristic of VNAs is aisle guides or rail systems that allow specialized narrow aisle forklifts and lift trucks to operate in aisles as narrow as 60-72 inches. Older conventional forklifts typically require aisles of 12 feet or more to turn and maneuver. This aisle space optimization is what enables VNA systems to achieve such impressive storage densities.
The density gains of VNA racking compared to standard wide-aisle selective pallet racking are quite staggering. Many operations see a storage capacity increase in the range of 25-40%. Some very efficient high-bay VNA configurations can achieve storage densities over 60% higher than traditional layouts.
Think about what that density increase could mean for a 100,000 square foot distribution center. Using a standard wide-aisle system, you might be able to store around 15,000 pallet positions. Convert that same footprint to a narrow aisle configuration, and suddenly you have over 21,000 available pallet positions. That’s a gain of over 6,000 more locations within the exact same building! For cramped, capacity-constrained warehouses, that translates to a tremendous boost in storage without any building expansion.
There are a few common configurations and equipment options when designing narrow aisle storage:
High-bay or multi-level VNA systems maximize vertical storage capacity with guide rails, specialty lift trucks like man-aboard trucks, and rack heights up to 30-40 feet or higher. These are ideal for ceiling heights over 24 feet.
For facilities with lower ceiling heights under 24 feet, single-level “flush configuration” racking maximizes density at ground level using turret trucks or reach trucks to operate in narrow aisles.
Some VNA layouts use deeper pallet positions where forklifts or specialized deep-lane trucks work within the racking itself. This can achieve up to 10-15 pallet positions per lane for incredible density.
Compared to conventional wide-aisle setups, VNA racks require specialized narrow aisle lift trucks and equipment:
Turret Trucks: These have a 180-degree rotating body and operate in a “cab-entry” method where the operator passes through the turret with the forks leading.
Man-Aboard Order Pickers: Lift operators can raise themselves along with the forks to pick orders or stock individual cases at height.
Reach Trucks: Specialized reach trucks can slide the forks in and out to work in extremely narrow spaces while the truck remains in the aisle.
Rail-Guided Trucks: Some VNA lifts mount directly to floor rails, drastically reducing aisle width needed since the trucks can’t swerve.
Such specialized equipment carries higher upfront investment costs but makes narrow aisles feasible. The density gains quickly pay off versus constantly leasing more space.
Beyond their space savings, VNA racks provide several compelling benefits for many operations:
Cost-Effective Expansion Alternative: For warehouses operating at capacity, a narrow aisle installation can exponentially increase available positions at a fraction of the cost of building additions or relocation.
Optimized Travel Paths: With less floorspace wasted on aisle footprints, travel distances during picks/putbacks are reduced. Operators can work more efficiently with less traversing.
Overhead Utilization: VNA systems, especially high-bay configurations, can better leverage overhead cubic space that’s often underutilized in warehouses with lower clearance runs of conventional racking.
Future-Ready Growth: Because of their density advantages, VNA systems “future-proof” with enough storage capacity to ride out growth for years versus a short runway of wide-aisle racking.
Worker Ergonomics: With lift equipment and case picking functionality, VNA configurations can enhance picking ergonomics over stooping, reaching, etc.
Bottom Line Improvements: The capital costs of converting to a narrow aisle layout are mitigated by lower operating costs, improved productivity, and avoiding expensive real estate expansions.
While the advantages of very narrow aisle racking are clear, it’s vital to factor in some key planning considerations and potential drawbacks:
1) Very Narrow Aisles Mean Reduced Selectivity
Because of their tight aisle and deeper pallet positions, VNA systems typically sacrifice some level of selectivity. Random accessibility to any specific SKU or pallet in the racks may be reduced versus selective wide-aisle racking.
Proper slotting, layout configurations, and product rotation strategies can mitigate selectivity issues. But for operations that absolutely require total random accessibility, narrow aisles may not be ideal.
2) Operator Visibility Concerns
Visibility is more restricted in tight aisles. Cameras, warning lights and specialized lift equipment help, but collision risks are heightened versus wide aisles. Optimal lighting, protective guarding on racks, and extensive operator training is needed.
3) Upfront Investment Costs
All that specialized VNA lift and rack equipment comes at a cost premium over basic pallet racks and lift trucks. While the payoff can be substantial in space savings, budget for higher upfront costs versus conventional setups.
4) Rack Configuration Limitations
Your facility’s building dimensions may not allow certain VNA configurations. For instance, very high-bay setups require ample ceiling height and vertical clearance many buildings lack.
5) Phased Implementation Complexity
Often, converting an existing wide aisle warehouse to narrow aisle racking must occur in phases. This can create hybrid configurations and temporary mixes of both systems that must be carefully managed.
If a narrow aisle system seems viable for your storage needs, the planning and design process should involve:
– A comprehensive facility audit to document building dimensions, column spacing, ceiling heights, weights/quantities of inventory, projected growth, etc.
– Thoroughly outlining your operational requirements around pallet types, SKU selectivity needs, product rotations, etc.
– Budgeting for racks, specialized lift equipment, implementation, etc. Certified professional material handling design assistance is highly recommended.
– Carefully phasing in the VNA conversion over time if necessary. Transitioning in sections allows ops to continue without disruption.
– Implementing rigorous systems, safety practices and operator training for VNA equipment and layouts.
– Performing routine safety inspections and maintenance to ensure rack system integrity.
Clearly, very narrow aisle racking represents a serious investment in optimizing storage density and capacity – but one with a serious payoff potential.
For operations continually coping with space constraints, explosive inventory growth, or the exorbitant costs of frequent facility expansions and moves, VNA could be a logical next step. However, the operational impacts of narrow aisles must be carefully weighed against any accessibility trade-offs.
If your facility checks the right boxes, you’ll find VNA delivers a stellar return on investment. And your cramped storage headaches could become a thing of the past.