MARVIN MANDEL, Governor                                      937

(5) CONSTRUCTION.—ON ENTRIES OTHER THAN
ROOM ENTRIES, STOPPINGS IN CROSSCUTS BETWEEN INTAKE
AND RETURN AIRWAYS SHALL BE BUILT OF SUBSTANTIAL,
INCOMBUSTIBLE MATERIAL, SUCH AS CONCRETE, CONCRETE
BLOCKS, BRICK, OF TILE. IN MINES WHERE PHYSICAL
CONDITIONS EXIST BECAUSE OF HEAVY OR CAVING GROUND
WHICH WAKES USE OF CONCRETE, CONCRETE BLOCKS, BRICK,
OR TILE IMPRACTICABLE, TIMBERS LAID LONGITUDINALLY
"SKIN TO SKIN" MAY BE USED. HOWEVER, THIS PARAGRAPH
DOES NOT APPLY TO RECOVERY WORK.

REVISOR'S NOTE: This subsection presently appears
as Article 66C, section 571(a) through (e),
inclusive, of the Code. The only changes

made are in style.

(H) DOORS AND OVERCASTS.—

(1)   IN GENERAL.-—DOORS USED ON MAIN-ENTRY
OR CROSS-ENTRY HAULAGE ROADS, WHICH WHEN OPEN WOULD
CONNECT INTAKE AND RETURN AIR COURSES VENTILATING THE
MINE, SHALL BE IN PAIRS TO PROVIDE AN AIR LOCK LARGE
ENOUGH TO CONTAIN AN ENTIRE TRIP. WHEN ONLY A SINGLE
DOOR IS INSTALLED, IT SHALL BE ATTENDED EXCEPT IN THE
CASE OF PANEL OR ROOM ENTRIES IN THE PROCESS OF
DEVELOPMENT. WHERE AIR LOCK DOORS ARE PROVIDED, THERE
SHALL BE SUFFICIENT LEAKAGE TO PREVENT AN ACCUMULATION
OF METHANE BETWEEN THE DOORS.

(2)    CLOSING.—DOORS SHALL BE KEPT CLOSED
EXCEPT WHEN MEN OR EQUIPMENT PASS THROUGH THE
DOORWAYS. MOTOR CREWS AND OTHER PERSONS WHO OPEN
DOORS SHALL SEE THAT THE DOORS ARE CLOSED BEFORE
LEAVING THEM.

(3)    CONSTRUCTION OF OVERCASTS.—OVERCASTS
SHALL BE CONSTRUCTED TIGHTLY OF INCOMBUSTIBLE
MATERIAL, SUCH AS MASONRY, CONCRETE, CONCRETE BLOCKS,
OR PREFABRICATED METAL, OF SUFFICIENT STRENGTH TO
WITHSTAND POSSIBLE FALLS FROM THE ROOF, AND OF AMPLE
AREA TO PASS THE REQUIRED QUANTITY OF AIR.

REVISOR'S NOTE: This subsection presently appears
as Article 66C, section 572 (a) through (c),
inclusive, of the Code. The only changes
made are in style.

(I) LINE BRATTICE.—

(1) WHEN REQUIRED.—SUBSTANTIALLY