Fall Protection General Requirements

Fall Hazard Recognition
Fall Protection Options
Fall Clearance Calculation
Minimizing Fall Forces

Fall Hazard Recognition

At Virginia Tech, a fall hazard exists whenever there is an unguarded working surface more than four feet above the next lower level (regardless of whether the work being conducted falls under general industry or construction). This includes work conducted from ladders, roofs, scaffolds, aerial lifts, work above dangerous equipment or areas which may be hazardous if fallen into, such as pickling or galvanizing tanks, degreasing units, unguarded machinery or electrical equipment, a body of water, or other similar situations.

Note: Access on many roofs is restricted due to potential respiratory exposures. For more information, go to Roof Access.

Generally, a permanent means of protection, such as a guardrail system, is installed to provide safe access for personnel who must work above or in the vicinity of such hazards; however, where appropriate fall protection does not exist, or where personnel may need to bypass the installed system, other means of protection must be implemented. The designated competent person is responsible for identifying such hazards, evaluating the situation, requiring a feasible means of protecting personnel, and ensuring that the protective system is effective. For assistance, contact EHS at 231-2341.

Fall Protection Options

Proper selection and implementation for any given fall hazard situation is critical. Whenever possible, the fall hazard must be eliminated permanently by proper design and access, permanant guardrails, and/or location of controls and equipment on ground level. Building-specific fall protection information is available on the Roof Access Chart.

Where fall hazards exist due to holes in floors, roofs, or other walking/working surfaces, covers must be installed. Openings in walls greater than or equal to 30 inches in height and at least 18 inches wide require a guardrail system or other appropriate means of protection.

• Covers must be capable of supporting, without failure, at least two times the maximum intended load (personnel, equipment, materials, etc.) that may be imposed on the cover at any one time.
• Covers shall be secured in place and marked with the word "Hole" or "Cover" to identify the potential hazard.
• Close roof hatches (unless guarded on all sides by a guardrail system) when on the roof to eliminate fall hazards.

Clearance Calculation

Whereas fall protection may be required at unguarded heights greater than four feet at Virginia Tech, that does not mean that a personal fall arrest system is the appropriate means of fall protection, or that its use is even feasible due to anchor point to lower level clearance distances. A typical personal fall arrest sytem may require up to 15 1/2 feet of clearance! Obviously this method of protection is not going to protect personnel working 4, 6, or even 10 feet above the ground.

To calculate the fall clearance distance, add up the following components:

• The length of the anchor point (if using a cross-arm strap),
• The length of the connecting device (i.e. lanyard or fall limiter),
• The length of deceleration for the shock-absorber (ex. extension of the lanyard when deployed),
• The average height of the person wearing the protection - typical estimate of 6 feet in height is used,
• A safety factor of three feet.

The total will indicate the minimum height of the anchor point necessary above the lower level in order for the system to be effective. The fall clearance distance can be reduced depending on various components used. For example, if a fall-limiter is used instead of a typical six foot lanyard and it is connected into a mounted anchor point rather than a cross-arm strap, the total clearance necessary for the system to work is only 15 1/2 feet. Other configurations may increase the necessary clearance distance.

Minimizing Fall Forces

The objective of a personal fall arrest system is to not only prevent impact with the lower level, but to minimize the fall forces imposed upon the body in the event of a fall. To understand the basic physics of a fall, take a look at the "Force at Impact" for a 200 pound person at various heights.

Elapsed Time	Distance Traveled	Velocity (fps)	Speed (mph)	Force at Impact
0.00	0	0	0	0
0.25	1 foot	8	5.5	400 lbs.
0.50	4 feet	16	11	1,600 lbs.
0.61	6 feet	20	14	2,400 lbs.
0.75	9 feet	24	16	3,600 lbs.
1.00	16 feet	32	22	6,400 lbs.
1.25	25 feet	40	27	10,000 lbs.
1.50	36 feet	48	33	14,000 lbs.
1.75	49 feet	56	38	19,600 lbs.

OSHA limits the amount of force that a person should experience during a fall to 1,800 pounds. Forces greater than this can result in internal bleeding, damage, or death. When a personal fall arrest system is used, a shock-absorbing lanyard or fall limiter is the only way to keep the fall forces less than 1,800 lbs. Typical force with a shock-absorbing connecting device is 900 pounds or less.