Rope Descent System
What is a Rope Descent System (RDS) and how does it work?
A Rope Descent System is a non-motorized system that uses gravity, with the worker controlling their rate of descent to access the interior and exterior facade of a building. The system’s friction device also allows workers to stop the descent and remain suspended at any location along their rope to perform their work. This system is commonly used by window cleaners.
Below are questions and answers to OSHA’s definition of an RDS, as defined in OSHA Subpart D. It is important that the designer understand OSHA’s use of these definitions to avoid confusion when designing an RDS.
What does a Rope Descent System consist of?
- “Rope descent system…usually consists of a roof anchorage, support rope, a descent device, carabiner(s) or shackle(s), and a chair (seatboard). A rope descent device does not include industrial rope access system.” (OSHA Subpart D. Section 1910.27 section (b)(l)(i))
- “Each employee uses a separate, independent personal fall arrest system that meets the requirements of subpart I of this part.” (OSHA Subpart D. Section 1910.27 section (b)(2)(vi))
- “Stabilization is provided at the specific work location when descents are greater than 130 feet (39.6 m)” (OSHA Subpart D. Section 1910.27 section (b)(l)(x))
What height limitations are there with a Rope Descent System?
OSHA restricts a rope descent to 300 feet, unless there isn’t another way to do the work or it poses a greater hazard by not performing a 300-foot rope descent. See OSHA’s 300-foot rule below:
“Use of rope descent systems. The employer must ensure: No rope descent system is used for heights greater than 300 feet (91 m) above grade unless the employer demonstrates that it is not feasible to access such heights by any other means or that those means pose a greater hazard than using a rope descent system…” (OSHA Subpart D. Section 1910.27 section (b)(2)(i))
What is the required load capacity for anchorages used for Rope Descent Systems?
OSHA requires each anchor to be capable of supporting at least 5,000 pounds. See OSHA’s requirements for anchor capacity for rope descent systems:
“Rope descent system–(1) Anchorages (I) Before any rope descent system is used, the building owner must inform the employer, in writing that the building owner has identified, tested, certified, and maintained each anchorage so it is capable of supporting at least 5,000 pounds (286 kg), in any direction, for each employee attached. Anchorages used to attach to personal fall protection equipment must be independent…capable of supporting at least 5,000 pounds (22.2kN) for each employee attached…” (OSHA Subpart D. Section 1910.27 section (b)(l)(i))
Caution! When Monorails, Davits, Outriggers and any other attachments are used as an RDS anchorage these must be capable of supporting at least 5,000 pounds. Further, OSHA requires each RDS employee to attach to an independent anchorage for their suspension line and an independent anchorage for their lifeline.
Rope descent system components:
1. Independent roof anchor, 5,000-pound minimum ultimate load capacity
2. Suspension Line (Blue)
3. Seat board
RDS requisite independent fall arrest system:
4. Independent roof anchor, 5,000-pound minimum ultimate load capacity
5. Full body harness
6. Lifeline (Red)
Does OSHA provide layout guidelines for anchors for rope descent systems?
OSHA requires proper rigging of rope descent systems. Basically, this means that each worker is required to be attached to two independent anchorages. One anchor is for a lifeline and the other for the suspension line. Anchors located within 15 feet of the edge require workers to observe OSHA fall protection rules.
Below are OSHA’s requirements for anchors used in a rope descent system:
“Each employee used a separate, independent personal fall arrest system…” (OSHA 1910.27 Subpart D for Rope Descent Systems section (vi), (See Fig. 1 and Fig. 4 pending addition).
- “(12) Anchorages used to attach to personal fall protection equipment must be independent.
- Tie- Back angle within 15 degrees is MARGINAL
- Tie- Back angle within 10 degrees is GOOD
- Tie- Back angle within 5 degrees is VERY GOOD
- Tie- Back angle 0 degrees THE BEST
Anchor Layout Diagram, based on the I.14 Window Cleaning Safety Standard
What is the building owner’s responsibility to contractors who use rope descent systems?
The owner is responsible for providing written assurance that the anchorages meet OSHA’s 5,000 load requirement. Anchor testing is required to confirm the anchor’s capacity. See OSHA’s anchor loading requirements below:
“Before any rope descent system is used, the building owner must inform the employer, in writing that the building owner has identified, tested, certified, and maintained each anchorage so it is capable of supporting 5,000 pounds in any direction, for each employee attached…” (OSHA Subpart D. Section 1910.27 section (b)(l)(i)
What is the employer’s responsibility to workers using rope descent access?
The employer must not perform work unless the building owner provides written assurance that the anchorages have been tested and certified within the previous 10 years, are inspected annually, and meet OSHA requirements. See OSHA’s requirements for the employer below:
“The employer must ensure that no employee uses any anchorage before the employer has obtained written information from the building owner that each anchorage meets the requirements of OSHA Subpart D, (b)(l)(i) of this section.
What is the timeline for building owners to comply with OSHA’s rope descent system requirements?
“The requirements…must be implemented no later than November 20, 2017.” (OSHA Subpart D. Section 1910.27 section (b)(l)(iii)
What can owners do if their buildings aren’t in compliance?
Building owners can get proposals from reputable companies for testing existing equipment as well as for installing new anchor systems or replacing failed anchors. While installing anchors may be costly, the building owner should weigh the risk of not complying with OSHA requirements. See the OSHA memorandum to OSHA compliance officers:
Is a counter weighted outrigger an acceptable substitute for permanently installed anchorages?
A counter weighted outrigger must have appropriate load capacity and must be tied back to an anchorage with a 5,000-pound load capacity. This is because a portable outrigger is a non-permanent anchorage requiring a tieback. Because the tieback is a component of the rope descent system it therefore requires an anchorage with a 5,000-pound load capacity. See OSHA’s requirement for non-permanent anchorages below:
“The rope descent system has proper rigging, including anchorages and tiebacks, with particular emphasis on providing tiebacks when counterweights, cornice hooks, or similar non-permanent anchorages are used…”(OSHA Subpart D. Section 1910.27 section (b)(l)(v))
“All components of each rope descent system, except the seat boards, are capable of sustaining a minimum rated load of 5,000 pounds (22.2 kN).” (OSHA Subpart D. Section 1910.27 section (b)(l)(vii))