Catwalks and Elevated Walkways
In a warehouse or distribution facility’s daily operations, getting from point A to point B is half the battle. It can also be the most time-consuming part of operations in a labyrinth of conveyor systems and equipment. Many facilities circumvent this issue by creating access points and walkways that avoid dangerous or hazardous areas and make daily operations more efficient. How frequently these walkways are used and by how many people could dictate drastically different design criteria.
For instance, walkways required in egress paths and potentially shorten egress paths are the most critical from a design and detailed perspective. As mentioned in our October technical tip on egress plans, a “means of egress” to exit the building is required for the building’s occupants. All areas that are determined to be part of the egress path are needed to be designed for 100psf live load, whether it’s on the floor, an elevated walkway, or even a stair. These areas require higher loading but also require width and height clearances that are more stringent.
On the other end of the spectrum are catwalks and maintenance walkways. These walkways are used to access equipment that is not as frequently used or accessed or provided as a secondary means of moving from point A to point B but not necessarily to exit the building.
Maintenance walkways are required to be designed for 60psf live load since there may be an occupant that needs to perform maintenance in the decked area and be on the platform for a more extended period. Catwalks that are purely for moving from one point to another can be reduced to a 40psf live load since they will have very light foot traffic and are seldom used.
The minimum width for these walkways is controlled by OSHA code and can be reduced to 18″ clear in some United States areas. However, customer specifications may be the controlling factor for the design and detailing of walkways.
SSI provides pre-engineered and pre-assembled walkway systems that can be used for maintenance walkways and catwalks and can be used in various situations. Low height walkway systems can utilize pre-assembled supports that provide flexibility in location but require field modification and assembly for specific lengths and have limited spans between the supports.
Suppose larger spans are required to clear openings or large access areas beneath them. In that case, a grid structure can be provided with the catwalk system sitting on top to minimize the installation time of installing individual members for a fully framed walkway. Lastly, catwalks can be hung from the ceiling to provide the least impact of support assemblies on the ground where space is at a premium.
However, an analysis of the roof or ceiling structure needs to be done by the building/owner engineer to determine if this option is feasible. Some buildings are not designed to support even the lightest of catwalk systems.
Pre-engineered and pre-assembled walkway systems are not recommended for egress walkways as they should be self-supporting structures to optimize design efficiency for the higher loading required. Also, these are not allowed in high seismic regions as they have limited capacity for potential earthquake loading. In comparison, installation times of pre-assembled walkway systems can be drastically improved compared to a stick-built structure. There may be potential problems as larger equipment may be needed to handle the bulkier and heavier pieces, and an experienced installer may be required for field modifications. Consult your SSI sales or engineering representative for the best solution for your catwalk and walkway problem.