August 10, 2010

Letter #20080529-8486

Re: Acceptable equivalent to control lines for a Controlled Decking Zone (CDZ) in steel erection activities.  29 CFR 1926.760(c)(3)

Question 1: What constitutes an acceptable equivalent to control lines used for a Controlled Decking Zone (CDZ)?

Answer: Section 1926.760(c)(3) states, in part:

The CDZ shall be marked by the use of control lines or the equivalent.

In addition, non-mandatory Appendix D to subpart R states, in part:

(1) When used to control access to areas where leading edge and initial securement of metal deck and other operations connected with leading edge work are taking place, the controlled decking zone (CDZ) is defined by a control line or by any other means that restricts access. [Emphasis added]

According to Appendix D, therefore, an equivalent to control lines should restrict access to the CDZ.  OSHA directive CPL 02-01-034, Inspection policy and procedures for OSHA's steel erection standards for construction, further explains:

Section 1926.760(c)(3) requires that the boundaries of the CDZ be marked "by the use of control lines or the equivalent."  In a CDZ, the control line restricts access by visually warning employees of an unprotected area (66 FR 5247).  Control lines can be made of rope, wire, tape, or other equivalent materials, but they must clearly designate the CDZ.  Examples of other acceptable methods would be a perimeter wall, guardrail system, or even a restraint system rigged so that non-leading edge workers could not access the area.  In contrast, a line painted on the floor would not be considered to be equivalent to control lines since it would be less visible than a control line. [Emphasis added]

In other words, an equivalent alternative to a control line must visually warn employees and clearly designate the CDZ.

The preamble to the proposed rule (available at 63 Federal Register 43451 (Aug. 13, 1998)) states that §1926.760(c)(3) is intended to limit access to the zone.  The preamble to the final rule (available at 66 Federal Register 5195 (Jan. 18, 2001)) explains that §1926.760(c)(3) requires that the boundaries of the CDZ be designated and clearly marked and that access be limited exclusively to those employees engaged in and trained in leading edge work.  The preamble to the final rule also describes control lines as creating a highly visible boundary that readily defines the CDZ and visually warns employees that access to the CDZ is limited to authorized personnel.

The standard, the directive, and the preamble explanations illustrate that the three elements required for control lines and their equivalent alternatives are (1) controlled access, (2) clear demarcation of the CDZ boundary, and (3) high visibility.  In other words, a control line or its equivalent alternative must clearly designate the CDZ with a visual message and must effectively keep unauthorized employees out of the CDZ.  If an alternative to control lines meets these three elements, that alternative would be considered equivalent to control lines.

Question 2: Is a control line used for a Controlled Decking Zone (CDZ) intended only to serve as a visual warning and not as a rigid structure?

Answer: Control lines are intended to serve mainly as a visual warning.  Non-mandatory Appendix D to subpart R is intended to guide employers in complying with §1926.760(c)(3).  If an employer follows the guidelines in Appendix D to establish a control line to demarcate a CDZ, OSHA will accept the control line as meeting the requirements of §1926.760(c)(3).

Appendix D describes the guidelines for control lines as follows:

(2) Control lines consist of ropes, wires, tapes, or equivalent materials, and supporting stanchions as follows:
 

(i)  Each line is rigged and supported in such a way that its lowest point (including sag) is not less than 39 inches (1.0 m) from the walking/working surface and its highest point is not more than 45 inches (1.3 m) from the walking/working surface.

(ii)  Each line has a minimum breaking strength of 200 pounds (90.8 kg).

Appendix D states that control lines may consist of ropes, wires, tapes, or equivalent materials attached to supporting stanchions.  Ropes, wires, or tapes are not rigid structures.  Because OSHA will accept control lines following the guidelines as meeting the requirements of §1926.760(c)(3), control lines do not need to be rigid structures.

In the preamble to the final rule, OSHA explained that it did not intend control lines to be the equivalent of warning lines in subpart M.  In fact, OSHA explained that control lines and warning lines serve different functions.  While warning lines provide direct physical contact with employees, control lines create a highly visible boundary that readily defines the CDZ.  The preamble to the final rule also states that, because of the direct physical contact, warning lines, which must have a minimum tensile strength of 500 pounds (see §1926.502(f)(2)(iv)), must be "substantially stronger and more rigid than a system whose primary function is to limit access by a visual warning" [66 Fed. Reg. at 5248].  OSHA's intent, therefore, is for control lines to serve mainly as a visual warning rather than a rigid, physical barricade.  Appendix D does, however, recommend that control lines have a minimum breaking strength of 200 pounds.  Appendix D is a non-mandatory appendix intended only to assist employers in complying with the standard and the minimum breaking strength is not stated in the text of the standard.

Question 3: Is a CDZ control line expected to be constructed of a horizontal cable, rope, wire, tape, or other equivalent material attached to vertical support members?

Answer: Control lines or their equivalent are likely to include horizontal cable, rope, wire, tape, or other equivalent material attached to vertical support members.  As stated above, the control line, or an equivalent, must (1) control access, (2) be highly visible, and (3) clearly demarcate the boundaries of the CDZ.  Appendix D's guidelines for control lines explain that control lines consist of ropes, wires, tapes, or equivalent materials, as well as supporting stanchions.  Appendix D also recommends that each line be rigged and supported so that the control line is between 39 and 45 inches from the walking/working surface.  Supports for the line can consist of stanchions, cones, columns, or their equivalent.  Control lines complying with these recommendations control access, are highly visible, and clearly demarcate the boundaries of the CDZ as long as they extend the length of the CDZ.

Please also note, however, that CPL 02-01-034 lists several acceptable alternatives to control lines that are not horizontal cable-type devices affixed to vertical support members.  These include a perimeter wall, guardrail system, or even a restraint system rigged so that non-leading edge workers cannot access the area.

Question 4: Is plastic warning tape affixed to stanchions considered an equivalent alternative to control lines?

Answer: Yes, plastic warning tape affixed to stanchions can be considered an equivalent alternative to control lines.  Appendix D states that control lines can consist of ropes, wires, tapes, or equivalent materials, as well as supporting stanchions.  In addition, as described above, the three elements required for control lines and their equivalent alternatives are (1) controlled access, (2) clear demarcation of the CDZ boundary, and (3) high visibility.

To be considered an equivalent, the tape must meet the three criteria and possess adequate strength to remain intact during its use.  Appendix D, paragraph (2)(ii) recommends a minimum breaking strength of 200 pounds.

Question 5: Are high visibility construction cones, placed along a CDZ, an acceptable alternative to control lines?

Answer: No, high-visibility construction cones, placed along a CDZ, are not an acceptable alternative to control lines.  As described above, the three elements required for control lines and their equivalent alternatives are (1) controlled access, (2) clear demarcation of the CDZ boundary, and (3) high visibility.  The construction cones themselves may be highly visible, but, due to the gaps between the cones, the cones would not control access or serve as a clear demarcation of the CDZ boundary.  Therefore, construction cones placed along a CDZ do not comply with the requirements in §1926.760(c)(3).

if you need additional information, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, Office of Construction Standards and Guidance, fax # 202-693-1689.  You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210, although there will be a delay in our receiving correspondence by mail.

Sincerely,



Ben Bare, Acting Director
Directorate of Construction