Cut-and-cover operation in the construction of tunnels.

An OSHA interpretation letter from 1978 addressing whether a partially covered cut-and-cover tunnel site falls under 29 CFR 1926.800, Tunnels and Shafts. It describes a covered section roughly 200 feet long, 31 feet high and 65 feet wide with open ends, and states that Subpart P applies to open cuts while Subpart 800 applies once covering limits access, airflow or daylight.