Using Warning Lines: Construction Best Practices
February 8th, 2010
The following information explains construction best practices for using a warning line to alert workers they are approaching an unprotected edge of a roof, floor, or other work surface.
OSHA addresses the use of warning lines in 1926.502(f). You should always review the OSHA standards to clarify any special circumstances you may encounter.
What is a Warning Line?
A warning line is a barrier such as rope, wire, or chain that warns workers they are approaching an unprotected edge of a roof, floor, or other work surface.
How do you set up a Warning Line?
Set up the warning line so that it keeps workers at least 6 feet back from the unprotected edge. This “setback” distance must eliminated the exposure and the risk that a worker could fall over the edge. You may need to increase the distance to eliminate the risk in some situations. Factors such as weather, visibility, the slope and condition of the work surface, the work being performed, materials handled, and the experience and supervision of the workers can increase the risk of a fall – even at a 6-foot set back. The correct setback distance eliminates the exposure and risk of a fall. If mechanical equipment is to be used, the warning line shall be erected not less than 6 feet from the roof edge which is parallel to the direction of mechanical equipment operation, and not less than 10 feet from the roof edge which is perpendicular to the direction of mechanical equipment operation.
Best Practices Include the Following:
The work surface should be relatively flat with a slope of no more than a 4/12.
The warning line shall be rigged and supported in such a way that its lowest point (including sag) is no less than 34 inches from the walking/working surface and its highest point is no more than 39 inches from the walking/working surface.
The warning line should be rope, wire, or chain. Avoid using plastic tape for a warning line; workers should be able to feel the line if they back up against it, eve if they’re wearing heavy clothing.
The rope, wire, or chain shall have a minimum tensile strength of 500 pounds, and after being attached to the stanchions, shall be capable of supporting, without breaking.
The warning line should be flagged at least every 6 feet with high-visibility material and have warning signs that are visible to workers.
Stanchions that support the warning line should be able to withstand a forece of at least 16 pounds, applied horizontally in the direction of the unprotected edge, without tipping over.
The line shall be attached at each stanchion in such a way that pulling on one section of the line between stanchions will not result in slack being taken up in adjacent sections before the stanchion tips over
No workers can enter the area between the warning line and the unprotected edge unless they are protected by a fall protection system in 1926.502 “Fall Protection Systems, Criteria, and Practices” unless the employee is performing roofing work in that area.
For additional information, or to register for one of our fall protection classes, please contact us at 417-576-4508 or click here.
