R 408.41479 Flooding; safety screens; runways.

Rule 1479. If there is a danger of rapid flooding in a tunnel that has a bore of 16 feet or more in diameter, then the employer shall provide both of the following: (a) A runway from the face to the bulkhead as high in the tunnel as practicable to maintain not less than a 6-foot vertical clearance from the surface of the runway upward to the surface of the tunnel. The runway shall be constructed of noncombustible material and shall have a standard railing installed securely along the length of the runway as prescribed in Construction Safety Standard Part 21 “Guarding of Walking and Working Areas,” and Construction Safety Standard Part 45 “Fall Protection,” as referenced in R 408.41410. If the runway is ramped under a safety screen, then the surface shall be made slip-resistant by cleats or other equivalent means. (b) Metal safety screens or other equivalent means installed with the bottom of the screen 4 feet above the surface of the runway. The first screen shall be located not less than 400 feet from the face of the tunnel. COFFERDAMS AND CAISSONS