Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-36 - Safety standards - Compressed air work › Section 296-36-195 - Special provisions for tunnels

Current through Register Vol. 24-14, July 15, 2024
(1)
Bulkheads.
The bulkheads
			 separating the working chamber from areas of lower pressure shall be of
			 sufficient strength to withstand safely the maximum pressure to which it may be
			 subjected. Where there is a possibility of rapid flooding of the working
			 chamber, such as might be present in subaqueous tunnels, the bulkhead shall be
			 located sufficiently close to the face or shield to permit escape of the
			 workers in case of an emergency. But in no case where there is such possibility
			 shall such distance be more than 300 feet.
(2)
Safety curtain or screens.
Where danger of a blow or an in-rush of water exists in tunnels 12 feet
			 or more in clear height, and the elevation of the top of the lining at the face
			 and of the completed tunnel back to the emergency lock are such that a safety
			 curtain will afford protection to the workman, a safety curtain shall be
			 provided. It shall be located where it will afford the maximum of protection in
			 case of an emergency but not impracticably close to the face.
Safety curtains shall be of incombustible material and shall be
				installed in the crown of the tunnel. They shall provide an airtight seal with
				the tunnel lining and shall be properly reinforced and braced as may be
				necessary. Curtains or screens shall be installed at right angles to the axis
				of the tunnel with the bottom edge horizontal. In tunnels up to and including
				24 feet in inside clear height, the safety curtain shall extend down to the
				center line of the tunnel. In tunnels over 24 feet inside clear height, it
				shall extend at least 12 feet below the inside clearance line of the roof of
				the tunnel.
(3)
Walkways.
In tunnels 16 feet or more in diameter, containing
			 safety curtains or screens, hanging walkways shall be provided from the face to
			 the man lock and shall be installed as high in the tunnel as is practicable.
			 Such walkway shall be installed above the tunnel floor and shall have at least
			 6 feet of head room above the walkway. A railing 42 inches high and a toe board
			 shall be securely installed throughout the length of walkways on open sides. In
			 areas under pressure, the walkways, stairways, and ladders including railings
			 shall be of incombustible material.
(4)
Maintenance of walkways.
Walkways and the stairs or ladders leading thereto shall be at all times
			 maintained clear, in good repair, and in a condition to carry safely the loads
			 to which they may be subjected.
(5)
Ramps.
Walkways shall be provided with ramps under safety screens.
			 Such ramps shall be provided with cleats.
(6)
Man lock and material lock.
Every tunnel shall have at least two locks in proper working condition,
			 one of which shall be used as a material and equipment lock and the other used
			 exclusively as a man lock.
(7)
Emergency man lock.
In subaqueous tunnels where space permits,
			 there shall be in addition to the man lock and the material lock, an emergency
			 man lock which shall be large enough to hold an entire heading shift and which
			 shall be kept open toward the face and maintained ready for use at all
			 times.
(8)
Location of locks.
Man locks and emergency locks shall be located as high in the tunnel as
			 space will permit but the emergency lock shall be located in the crown of the
			 tunnel.
(9)
Track safeties
			 and brakes.
An automatic stop block or derailing device shall be
			 provided at the top of every slope or incline greater than 3 percent. In
			 addition, such a device shall be installed at a point not less than 150 feet
			 nor more than 200 feet upgrade from any point where runaway cars may cause
			 damage to the shield or air lock. A holding device shall be provided for cars
			 used on inclines. Such device shall be set in the holding position during
			 loading.
Rules (Part XVII), filed 12/28/62; §§ 10 and 18,
				  filed 3/23/60.