Modular, free-standing demarcation warning lines from High Engineering provide high visibility to controlled access zones.

Referred to as an administrative control in the hierarchy of fall protection, High Engineering warning line systems are used to warn employees of fall hazards such as an unprotected edge or to designate areas as safe, dangerous or restricted.

Integrated Kee Klamp fittings produce a solution that is perfect for use indoors or outdoors. The simple modular design makes it quick and easy to assemble and dismantle. Designed with weighted bases to keep this warning line system upright throughout all seasons and high visibility flags placed every 1.8m (6 ft) to make sure it’s seen.  Independently tested and engineered to exceed National and Provincial regulations.

OH&S Compliant

Pre-engineered to deliver the strength and durability our site-specific warning line layouts are developed by competent and qualified fall protection specialists that validate compliance using national and regional safety regulations.


Securely and visually delineates your authorized and safe working areas using recycled PVC stanchion bases that spread the point load without sacrificing load resistance or damaging or penetrating the rooftop.

Agile Deployment

Provides flexibility to seamlessly connect to most rooftop structures including beams, panel walls, existing guardrail, and adapts to a broad range of roof types enabling rapid deployment and minimized downtime.

Long Lasting

Tested to withstand 105 MPH winds these systems feature PVC-coated stainless-steel cable, galvanized upright posts and bases made of solid, recycled rubber that will last as long as your facility.

Warning Line Resources

Advantages Kee Mark Warning Line

  • Provides high visibility to controlled access zones
  • Simple modular design
  • Easy, quickly assembled and dismantled
  • Cost effective solution for demarcation
  • Low maintenance
  • Free standing
  • Suitable for indoor and outdoor use, unique design can stand up to adverse weather
  • Many applications: Controlled access zones, Isolate equipment, Machinery demarcation, Trade shows, Ground level for queue management, and more.
  • Meets applicable North American regulations

Warning Line Standards

Control Zone 

Source: Alberta Occupational Health and Safety Code 2009 

Section 161 Control zones
The use of a control zone is an approach to fall protection that places special requirements on workers and work being performed on a nearly level working surface within 2 metres of an unguarded edge from which a worker could fall. Control zones can be used on surfaces having a slope of up to 4 degrees measured from the horizontal. 

If a worker works within 2 metres of the control zone i.e. within 4 metres of the unguarded edge, a raised warning ling or equally effective means is required. If a worker works within the control zone, then a travel restraint system must be used. A control zone cannot be used if the level working surface on which work is being performed is less than 4 metres wide. In such circumstances, one of the other methods of fall protection required by the OHS Code must be used. 

Work away from unguarded edge

Situations may arise where, on a large flat roof for example, work is performed at a significant distance away from an unguarded edge e.g. at a penthouse near the center of the roof. With the exception of when workers enter or leave the work area at an unguarded edge, workers have no contact with the edge. Upon accessing the roof, workers must proceed directly to their work area. Under such circumstances, a line defining a control zone is unnecessary, as are the remaining requirements for fall protection that would normally apply at the unguarded edge.

Line Defining the Control Zone

If a worker works within 2 meters of the control zone i.e. within 4 meters of the unguarded edge, a raised warning line or equally effective means of alerting the worker to the unguarded edge is required (see Figure 9.25). The raised warning line or other equally effective means such as barricades must be placed at least 2 metres from the edge. The warning method provides a visual and physical reminder of the presence of the hazard. 

For compliance purposes, a raised warning line can consist of ropes, wires or chains, and supporting stanchions, and should be 

a. flagged or marked with highly visible materials at intervals that do not exceed 2 meters (6.5 feet), 

b. rigged and supported so that the lowest point (including sag) is not less than 0.9 meters (34 inches) from the walking or working surface and its highest point is not more than 1.2 meters (45 inches) from the walking or working surface, 

c. attached to 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 the adjacent section before the stanchion tips over, and 

d. the rope, wire or chain must have a minimum tensile strength of 2.2 kN (500 lbs). 

An “equally effective method” might be a substantial barrier e.g. pile of materials or supplies, tall parapet, building system pipes and ducts, etc. that is positioned between the worker and the unguarded edge, preventing the worker from getting to the edge. Since this substantial barrier is acting as a guardrail, it must at all time be at least 920 millimeters (36 inches) tall while the protected worker is using it.

Rooftop Warning Line
Need Additional Help?

Whether your project is a self-installation, supervised installation, or you require turnkey services, High Engineering Fall Protection specialists are standing by to assist you. Get started by requesting a quote or contact us at (403) 808-3702.

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