OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

April 30, 1975

Subject: Request for Interpretation

This is in response to your memorandum dated April 2, 1975, and subsequent telephone conversation regarding an interpretation defining, "Tunnel", and the application of Section 1926.800 as it would apply to the Morrison-Kundsen operation in the construction of the Metro system.

A subway tunnel constructed by the "cut and cover" method becomes a tunnel when the section under construction is completed and back filled. Thereby, creating hazards or environments that could be germane to tunnel operations.

An employer would be cited for an alleged violation of a standard in 29 CFR 1926.800, Tunnel and Shafts, when; (1) an employee's worksite is in a tunnel, (2) employee is engaged in construction work as defined in 1910.12(b), and (3) the employee is exposed to a hazard that is an apparent violation of a standard in the 1926.800 section.

In regard to 1926.800(a)(6), enforcement of this standard would depend upon the operations inspected and the conditions observed. The intent of this standard was to have an accurate account of those employees engaged in tunneling operations underground in case of accidents which require search and rescue operations. In areas where such employees are relatively safe, such as in cut and cover operations where the decking is temporary, a check in - check out system is a highly recommended practice, but is not mandatory. Each alleged violation should be determined on its own merit in the enforcement of the 1926.800 standards.

Barry J. White
Associate Assistant Secretary for
Regional Programs