The lowdown on Very Narrow Aisle (VNA) Racking

The last few years have seen the logistics industry race to streamline and maximize warehouse efficiencies, particularly in countries like New Zealand where vacancy rates have been at record lows and development and rental costs have rapidly inflated. As a consequence we have experienced a surge in the adoption of Very Narrow Aisle (VNA) racking systems. Despite the increase in popularity, we still see the industry experience challenges implementing VNA. This article aims to give a high level view of VNA - what is VNA racking, why an operator would choose VNA, what it means for property requirements, and some tips for approaching a VNA project.

What is Very Narrow Aisle racking?

VNA (Very Narrow Aisle) Racking is a type of warehouse storage system where the aisles between the racks are much narrower than traditional systems. Typically aisles will be less than around 2 meters wide - in comparison with a more traditional racking layout where aisles will range from 2.5 - 4 m width. The tighter aisle spacing allows for a higher storage density, as more racks can be placed in a smaller area. The racks are accessed by a specialised fork trucks that are designed to work with VNA. These will often be wire guided and designed to operate at high speeds and high picking heights.

Why implement VNA?

VNA can increase storage capacity within a warehouse by as much as 65% by increasing racking coverage (narrower aisles), and allow picking heights of up to 18 m. This increase in storage density has become very attractive as space has become scarce and property costs have inflated.

With VNA able to support fully Automated Guided Vehicles (AGVs), it has become an even more attractive investment. Automation allows greater productivity/throughput with fewer fork trucks and operators. Higher storage density, faster throughput, and potentially lower operating costs make for an enticing proposition!

What does VNA mean for property specs/requirements

Forklifts in VNA facilities travel at greater heights, faster speeds, and with less clearance between racks than in a more traditional facility. This means that you need a radically flatter floor to get safe and efficient performance out of VNA. The denser and higher racking also means that the point loads on the floor can increase significantly and knee/apex height will be lifted. These requirements mean that the cost for new builds for VNA facilities will tend to be higher than otherwise, and that there might be some limitations or unanticipated costs related to the conversion and upgrade of older facilities (although conversions are a great option to get more value out of an existing warehouse facility). I've written a primer on concrete floor flatness standards previously and this covers off the key difference between specifications for traditional wide aisle vs. VNA racking and what it means for construction methodology here:

https://www.dhirubhai.net/pulse/world-isnt-flat-your-warehouse-floor-should-tim-walker/

Tips for approaching a VNA project

Whether you are looking at a new build project or the conversion of an existing facility there are some simple steps you can take to help make a VNA warehouse project a success.

1. Specify floor flatness correctly. All suppliers of MHE/fork trucks for VNA will have a floor flatness specification that the floor must meet for safe and efficient operation of their fork truck. Whether it is FMIN, VDMA, DIN or TR34 DM flooring specification, if there is an issue with the performance of the fork truck, increased maintenance or, in a rare situation, an accident, this is the first thing that will be looked at.
2. Design the floor for the appropriate loads. VNA racking will often mean a heavier load on the slab - make sure this is covered off in the design process. If converting an existing facility this might mean a capacity check by a specialist consultant and looking at some floor upgrade options to strengthen the floor.
3. Pay attention to little details that matter: floor joint layout and detailing, construction methodology such as method of casting or grinding slabs, and details like accomodating for wire guidance will all make a difference to the successful operation of a VNA facility. Ideally engage with specialist consultants and contractors experienced with VNA facilities.
4. Verify the floor slab performance - Once the floor is cast/installed independently test the floor specification. Incorrect floor flatness is the main problem we see when asked to investigate an underperforming VNA facility and is easily avoided by following step 1. (correct speficiation) and then getting a testing company in to verify conformance.
5. Test the system - as well as the floor flatness being correct, it's crucial that racking is installed to the correct tolerances and that the specialist VNA fork trucks are fully tested and commissioned. In my experience some troubleshooting and tuning of the system can be required - so allow a little bit of time in your programme for shaking things out.

Summary

VNA (Very Narrow Aisle) Racking is a type of warehouse storage system where the aisles between the racks are much narrower than traditional systems, typically less than 2 meters wide. This allows for a higher storage density, as more racks can be placed in a smaller area. The racks are accessed by specialized fork trucks that are designed to work with VNA, often wire-guided and designed to operate at high speeds and high picking heights. VNA can increase storage capacity within a warehouse by as much as 65% by increasing racking coverage (narrower aisles), and allow picking heights of up to 18 m. This increase in storage density has become very attractive as space has become scarce and property costs have inflated. However, implementing VNA requires a flatter floor to get safe and efficient performance, and the denser and higher racking means that the point loads on the floor can increase significantly, which can lead to higher costs for new builds or limitations and unanticipated costs related to the conversion and upgrade of older facilities. To ensure a successful VNA implementation, it's important to specify floor flatness correctly, design the floor for the appropriate loads, pay attention to little details that matter, verify the floor slab performance, and test the system.

Feel free to reach out if you have more questions about VNA racking and what it might mean for your building or project.