When Eric Cohen joined San Diego-based WAXIE Sanitary Supply in 2000, he was tasked with a tall order as the jan/san distributor's new vice president of logistics.

After outgrowing its Hayward, Calif., warehouse after just six years, Cohen was given the daunting assignment of designing WAXIE's new distribution center in nearby Livermore, Calif. Instead of following the company's standard warehousing blueprints that included 10.5-foot wide aisles and pallet racking no taller than 20 feet high, Cohen drew up a new design to better utilize the space.

"I said, 'Hey, we got these 10.5-foot aisles, lets shrink them down to anywhere from 6 feet to 5.5 feet and go as high as 28 to 30 feet vertically with our racks,'" Cohen recalls. '"That will give us some more space.'"

Cohen's redlines were approved by management and implemented shortly thereafter. By shrinking down the size of the aisles with the use of narrow-aisle technology and stacking products up to the ceiling, the company was able to gain nearly 50 percent more rack space in the same footprint. After implementation, the company also quickly noticed marginal increases in productivity among its warehouse staff. And because narrow-aisle racking was successful in its Livermore facility, the company has since rolled out the same warehouse configuration into three of its other newly-constructed facilities.

"Our main focus is on maximizing space so we don't have to move out or change locations after a few years," says Cohen. "What's nice with this layout is instead of having a 150,000-square-foot warehouse, we can have a 100,000- or 120,000-square-foot warehouse and still have the same cubic storage volume."

One of the most significant costs that distributors have is managing their cost per square foot. As a result, utilizing more with less has become a mantra that many distributors are preaching nowadays in order to extend their facilities' lifecycles. Whether they're slimming down their aisles or stacking products up to the ceiling, every nook and cranny of the warehouse is now being scrutinized to eliminate any wasted space.

Narrow Aisles

Warehouses are built and equipped on the basis of handling projected volumes and a set number of products. However, steady growth, changing storage requirements and an increase in service requirements often throw distributors for a loop and they find themselves out of space. As a result, distributors scramble to open up areas in their warehouses to store product. Sometimes distributors can alleviate their space constraints by performing minor facility alterations to their warehouses.

Distributors are also turning to narrow-aisle racking in order to make better use of their existing or new spaces. At the same time, they're also finding that they can create an efficient material handling system and a good working environment.

Davidson, N.C.-based JanPak Inc., began implementing narrow-aisle racking in its warehouse seven years ago. Coupled with the company's warehouse management system (WMS), the company was able to boost picking velocity.

"Our productivity and lines per hour were languishing in the 12 and 15 range in terms of pick velocity and now we are in the 30 to 40 lines per hour range at our best facilities," says Chris Householder, JanPak's executive vice president.

A typical aisle in a narrow-aisle warehouse is under nine feet. Narrow aisles permit more efficient use of floor space than conventional wide aisles and can save more than 30 percent of space or more, according to distribution studies. Storage height can also be used more effectively in a narrow-aisle distribution center, which allows for optimum storage capacity.

Very Narrow Aisles

Some distributors are gaining even more space in their warehouses by shrinking their racking down even further with very narrow aisle (VNA) racking, where aisles are typically six feet wide or less.

"In a typical area where you have a narrow aisle, you can get two aisles of very narrow aisle," says Householder. "We can also distinguish literally 10 times the number of bin locations in a very narrow aisle than in a standard narrow aisle."

JanPak dedicates a small portion of its warehouses for VNA racking, which according to Householder, is ideal for space-saving storage of slow-moving product.

"We have a lot of 'C' items in our system and we found very narrow aisle to be a very effective place to put those items," he says. "In our Dallas facility, our very narrow aisles are racked nearly to the ceiling, so we have that rack going 24 feet high. You can put a lot of small products in there such as feather dusters, squeegees and things like oddball trigger sprayers that might not be fast movers."

Distributors say the biggest benefit to narrow aisles and very narrow aisles is utilizing several small picks in a shorter traveling distance.

"Each bin has it's own very distinct mailbox-sized location and an address," says Householder. "With our WMS, it takes you there, you don't have to have the challenge of losing that product or the time it takes to find the product."

VNA also utilizes rail-guided or wire-guided technology. Rail-guided aisles essentially have 3- to 4-inch curbs, and wire-guided technology works off of a wire frequency that's embedded in the warehouse floor. The key to using these technologies is that they both promote safety, as they keep a forklift driver from crashing into the racking.

At WAXIE, the company's very narrow aisles are wire-guided, so as the operator drives into an aisle with a specially-designed turret truck for the operation, the operator turns on the wire guide signal on the truck. When the machine picks up the wire frequency signal from the aisle floor, the operator is "locked in" and can drive down the aisle at increased speeds, hands-free.

Making The Switch

There are drawbacks to narrow aisle racking that still have some distributors questioning if it's efficient enough for their facility, however.

One is full pallet put-away can be a rather cumbersome and complex process. Unlike a wide aisle where lift trucks can breeze down an aisle and pick, make a 180-degree turn and go back, narrow aisles often are too small to allow for other operators to make a pass in an aisle.

Distributors like WAXIE and JanPak have been able to reduce traffic jams in their narrow-aisle facilities by strategically placing their fastest-moving stock on the outside aisles. These aisles are a little larger than the others encased by racking on both sides, so the picking operators are able to make a pass as needed.

Retrofitting existing facilities for narrow aisles can be pricey and often difficult, too. The floor is a sensitive part of a high-bay storage plan and it must withstand the heavy concentrated loads imposed by high racking. The floor must be flat and the higher the racking, the more level the floor must be. Otherwise, the uneven floor may cause a lift truck to sway and hit a portion of the racking at high heights, resulting in serious damage or injury.

When thinking about transitioning to narrow aisles, distributors must also consider the money it will cost to upgrade their lift truck fleet. Regular lift trucks aren't ideal for these situations and don't have the ability to go 20-plus feet high to stock and pick items. In fact, WAXIE had to purchase turret trucks that are valued at close to $100,000 a piece for its narrow-aisle warehouses. These trucks, also referred to as "man-up trucks" allow warehouse employees to rise up to the level of product, so they are eye level with the product during picking and put-away.

When distributors are looking to optimize their existing warehouse space, narrow aisle and very narrow aisle racking are logical solutions to extend the life of a facility.