Many companies install mezzanines, elevated work platforms or multi-level racking systems to create additional storage space or work areas above existing operations. In many cases, expanding "up" is less costly and time-consuming than expanding "out" (which usually means adding onto existing space, leasing new space or building a new facility).
Building upward creates a number of advantages and efficiencies, but take care: unprotected mezzanines or multi-level environments pose a high risk for employee falls. According to the Occupational Safety and Health Administration (OSHA), falls are among the most common cause of serious work-related injuries and deaths. In 2011, 666 U.S. workers were killed in falls, slips, or trips—accounting for 14 percent of all fatal work injuries. Falls to a lower level accounted for 541 of those fatalities.
Section 6.4.3 of the standard states: "Any gate that provides an access opening through the guards for the purpose of loading and unloading material onto a work platform shall be designed such that the elevated surface is protected by guards at all times. Gates that swing open, slide open, or lift out leaving an unprotected opening in the guarding are not acceptable."Many safety-minded companies look to organizations like the American National Standards Institute (ANSI) for best practices. In 2009, ANSI issued a standard titled, "Specification for the Design, Manufacture and Installation of Industrial Work Platforms (MH28.3: 2009)."
Based on current standards, industrial mezzanines must have handrails and gates around all edges; however, these gates need to be opened from time-to-time to accommodate the loading and unloading process. According to the ANSI standard, there must be full-time protection when loading and unloading materials from an elevated platform.
One possible solution is a dual reciprocating barrier (like Rite-Hite's GateKeeper, www.RiteHite.com). When the outer gate opens to allow pallets to enter the mezzanine, the inner gate automatically closes to keep workers out. After the pallet is received, mezzanine-level workers open the inner gate to remove material from the work zone while the outer gate closes to secure the leading edge of the platform. To prevent the outer gate from being raised by a worker inside the work zone, the latch can only be accessed when standing outside the work zone.
Some manufacturers provide two-tier mezzanines built without bolts or welds, like this design from Metalsistem (www.metalsistem.com). This is said to contribute to lightweight and high-strength performance, taking advantage of the properties of 3.1B (EN10204) certified high-tensile steel. In this design, the shelving, which is a closed section without perforations or cut-outs, enables connections to be made on eight points along four faces. This allows for the creation of mezzanine structures such as shelving, catwalks, platforms and rack supports in a variety of forms and configurations.
Briggs & Stratton's primary distribution center in Milwaukee added 150,000 sq. ft. onto its existing facility to store 30,000 more SKUs and to improve order fulfillment. They avoided adding their originally anticipated 225,000 sq. ft. by working with Cubic Designs (www.cubicdesigns.com) and Storage Systems Midwest (www.ssmidwest.com) to customize a mezzanine for vertical storage. The resulting two-level mezzanine provides three levels of storage and was designed to fit the 34' tall space. The mezzanine's footplates and columns were installed below the concrete floor for added structural support. Concealing the footplates also reduced obstructions, as did minimizing the number of columns. A catwalk and ramp were installed to connect the new mezzanine to existing mezzanine racking and storage in the adjacent building.