What Does
Controlled Access Zone Mean?
A controlled access zone (CAZ) is an area of a construction site that only certain workers are authorized to access due to the risk of falling from heights. They are, specifically, elevated areas without guardrails or other fall protection systems in place.
A CAZ is only permitted for certain types of work that make typical fall protection measures impractical, such as:
- Construction at leading edges
- Overhand bricklaying
- Precast concrete erection work
In every other case, employers must implement fall protection measures to protect workers before any work can take place.
How OSHA Defines Controlled Access Zones
OSHA standard 1926.501(b)(9) defines a controlled access zone as “an area in which certain work (e.g., overhand bricklaying) may take place without the use of guardrail systems, personal fall arrest systems (PFAS), or safety net systems, and access to the zone is controlled.”
Conventional fall protection measures must be used by workers inside a CAZ who are exposed to fall hazards associated with hoist areas, runways, ramps, and holes.
Designating a CAZ prevents unauthorized personnel from wandering into a fall hazard zone. Falls from heights are often fatal but can almost always be prevented by implementing fall prevention measures. The construction industry has the highest fatal work injury rate, with about 36% of fatalities that occurred in 2022 being attributable to falls to a lower level. Creating controlled access zones is one of the measures aimed at preventing these incidents.
Safeopedia Explains Controlled Access Zone
OSHA Requirements for Controlled Access Zones
Overhand Bricklaying
In overhand bricklaying, the mason has to lean over the wall to lay bricks and masonry units. Since guardrails would impede this task, it can be performed without fall protection systems so long as it is within the boundaries of an authorized CAZ. However, only personnel who are critical to the wall construction are allowed inside this zone, including electricians and plumbers who are needed to integrate necessary components into the wall.
While guardrails are not required, other fall protection measures such as safety nets and personal fall arrest systems (PFAS) can still be employed.
Regulations for overhand bricklaying and related work can be found in CFR 1926.501(b)(9).
Leading Edge Work
A leading edge is any unprotected edge or opening that presents a fall risk. Typically, this refers to the edge of a roof, but it can also be the edge of a floor that is under construction, a manhole, or formwork.
In addition to the danger of falling off a leading edge, there’s also the possibility of a lifeline being severed by the sharp edge. These lifelines are intended to stop a fallen worker from hitting the lower level, but some leading edges compromise that ability.
Regulations for working on a leading edge can be found in CFR 1926.501(b)(2). In most cases, employees working on a walking-working surface six feet or more above a lower level where the leading-edge work is in progress must be protected by guardrail systems, safety net systems, or PFAS.
Exceptions can be made, however, if the employer can demonstrate that the use of fall protection systems poses a greater hazard. In which case, they can instead create a controlled access zone to ensure that only necessary personnel are near any unprotected leading edge.
Residential Construction
Residential construction refers to construction work intended for residential use, up to a maximum of four floors. This includes building, renovating, or expanding single-family homes, condominiums, townhouses, and other residential structures.
According to CFR 1926.501(b)(13) employees working on a residential project six feet or more above lower levels must be protected by guardrail systems, safety net systems, or personal fall arrest systems. Where the use of these is not feasible, the employer must develop and implement a fall protection plan in accordance with standard 1926.502(k)(7), classify the location as a controlled access zone, and restrict access accordingly.
Precast Concrete Erection
Precast concrete is made and cured at a factory before it is brought to the construction site, where it is erected using lifting equipment. These precast elements include walls, columns, slabs, and stairs.
Erecting these concrete elements on higher floors introduces a number of hazards, such as being struck by the precast element or being crushed between it and another object. It also poses a fall hazard for the workers who are setting it in place and may have to do so near an unguarded leading edge.
OSHA’s CFR 1926.501(b)(12) requires guardrail systems, safety net systems, or PFAS for employees engaged in these operations at six feet or more above the lower level. If this is not practicable, the employer will need to demarcate a controlled access zone and follow all regulations associated with it.
Control Lines Used in Controlled Access Zones
The boundary of a controlled access zone is defined by control lines erected at least 10 feet from the leading edge.
Control lines are made of tape, wire, or rope and are supported by stanchions. They are used to visually demarcate the area that is restricted to unauthorized personnel.
According to OSHA, the three essential elements of a control line are:
- Controlled access (effectively restricts entry to anyone who isn’t authorized to work in the CAZ)
- Clear demarcation (unambiguously delineated the boundaries of the CAZ)
- High visibility (uses materials that are easily seen or adds colorful flags to the line to increase its visibility)
Control lines mainly serve as a visual warning and differ from warning lines, which must have a minimum tensile strength of 500 pounds.
Any control line used to demarcate a CAZ must follow the requirements outlined by OSHA in 1926.502(g):
- It must be erected at least 6 feet from the edge (and no more than 25 feet)
- When erecting precast concrete, the maximum is 60 feet (or half the length of the element, if it is less)
- For overhand bricklaying, the line must be between 10 and 15 feet from the working edge
- It must extend the entire length of the unprotected edge and be roughly parallel to it
- It must be connected on each side to a guardrail or wall
- It must enclose the entire CAZ
- The line must have a flag or other highly visible material attached at every six-foot interval
- It must be rigged and supported such that the line at all points is between 39 and 45 inches from the walking-working surface
- It must be able to withstand at least 200 pounds of weight
Implementing a Controlled Access Zone
The first step to implementing a controlled access zone is to determine whether one is needed. The employer must develop and implement a site-specific fall protection plan that includes fall protection measures and fall safety training for all employees who might work at heights.
If leading edge, masonry, or precast concrete work is being done in an area that makes standard fall protection measures impractical or unsafe, the employer must instead establish a controlled access zone.
While the area will be marked with a simple control line system, creating a CAZ mainly involves establishing, communicating, and enforcing rules and procedures. Primarily, designating authorized personnel and restricting access to all other employees.
OSHA provides employers with a set of criteria for controlled access zones:
- The area must be clearly defined, with posted signage to prevent entry by unauthorized personnel
- Employees working in a CAZ must be supervised by a competent safety monitor who is able to recognize fall hazards
- The safety monitor should be on the same walking-working surface, within sight of the employees and close enough to be heard by them
- The safety monitor must immediately warn an employee if they are acting unsafely or are unaware of a fall hazard, and employees must quickly respond to any warnings or prompts by the safety monitor
- The safety monitor must not have conflicting responsibilities – they must be able to remain alert, recognize hazardous situations as they arise, and warn workers without delay
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