Generac Power Systems

The first implementation of non-traditional aisles was at the Whitewater, Wisconsin distribution center of Generac Power Systems. Generac manufactures and distributes portable electric generators, which are typically stored and handled on pallets. The Whitewater DC was built in 2007, after logistics managers saw an article on our work in a trade journal.

The design is essentially a fishbone, but with single-deep pallet rack in the central area, floor storage in the right section, and pallet flow rack and other storage in the left section.

An interesting challenge in any implementation of non-traditional aisles is building columns. Generac managed to place aisles around the building columns, with the single exception you see in the center of this photo. Unfortunately, this is also in a heavy traffic zone. Managers at the DC installed the bumper you see here after a worker grazed the column during normal operations. The general manager told me that if he could do it over again, he would have paid the extra money to reinforce the ceiling above this column, in order to get rid of it.

View from a forklift seat, as the driver looks back to enter the cross aisle.

One lesson learned from this DC is the need for safety mirrors at intersections of aisles, as you see in the photo to the right. Although in single-command operations workers will make only 45 degree turns, they still must look back 135 degrees before entering the main cross aisles. Fortunately for Generac, the height of their products leaves a small gap above the pallet that improves visibility.

Forty-five degree turns have an additional benefit that we had not considered when developing this work.  When we asked workers at Generac how they liked the new design, one worker replied, “We really like it. Now we can take turns at full throttle.”

Speaking of full throttle turns, the photo to the right shows the entrance from a picking aisle into the cross aisle. Notice the building column about 30 feet down, just to the right of the cross aisle. The next photo shows what happens when workers take that turn just a little too fast. The red plate was welded on to repair damage from a fork, after a forklift pierced the column at high speed. Fortunately, no one was hurt.

Generac wanted the flexibility to move easily between picking aisles in this warehouse, even though it was planned to be a unit-load warehouse only.

A middle aisle to facilitate future order picking.

As we have written repeatedly, the fishbone and flying-V designs are not intended to support order picking operations, in which workers visit multiple locations. Generac wanted the flexibility to do order picking in the future, so they inserted a middle aisle in the middle section, which makes the cross aisles form a sort of “inverted triangle.”

We would like to thank the courageous souls at Generac for this pioneering implementation! If you would like to learn more about how the warehouse is working, I can put you in touch with their general manager, who has graciously agreed to discuss his operation with interested logistics professionals.


  1. Hi ! I work for a big Supply Chain company at the Solutions Design department. I’ve benn trying to suggest to our new clients this kind of solution, using simulations to prove this is better than a classical aisle design for some many reasons. But, we unfortunatelly have some skeptical persons who cannot think outside the box… I will keep trying! Thanks Kevin!

      1. I am trying to improve warehousing for large appliances and furniture. Would Chevron model be best fit for it? I want to talk more about it

  2. Amazing! Is there any picture from the roof to the racks? Is there any estimated saving or productiviness improvement already? If so, would you mind to share?

    1. Unfortunately, this DC was a greenfield consolidation of some smaller warehouses, so there was not base case against which to compare. I do have an AutoCAD of the site, but am not free to share. Sorry.

  3. Hi! I’m Juan Valencia, student of Industrial Engineering at Universidad del Valle-Cali,Colombia. With my partner Juan Chacon and our tutor Leonardo Rivera, we are making an Economic analysis of the implementation of a non-traditional warehouse layout.
    We would like to ask some questions to Generac about the functionality of the DC and we would appreciate if you help us putting in contact with their general manager.

    Thanks and we look forward your prompt response.

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