DEPARTMENT OF LABOR AND ECONOMIC OPPORTUNITY  
DIRECTOR'S OFFICE  
CONSTRUCTION SAFETY AND HEALTH STANDARD  
(By authority conferred on the director of the department of labor and economic  
opportunity by sections 19 and 21 of the Michigan occupational safety and health act,  
1974 PA 154, MCL 408.1019 and 408.1021, and Executive Reorganization Order Nos.  
1996-2, 2003-1, 2008-4, 2011-4, and 2019-3, MCL 445.2001, 445.2011, 445.2025,  
445.2030, and 125.1998)  
PART 14. TUNNELS, SHAFTS, CAISSONS, AND COFFERDAMS  
R 408.41401 Scope.  
Rule 1401. This part applies to the construction, modification, and major repair of  
tunnels, shafts, caissons, chambers, passageways, cofferdams, any other aspect of tunnel  
construction, and the use and maintenance of equipment. This part does not apply to  
routine maintenance of an existing structure; excavation and trenching operations as  
prescribed by Construction Safety Standard Part 9 “Excavation, Trenching and Shoring,”  
which is referenced in R 408.41410, or underground electrical transmission and  
distribution lines as prescribed in Construction Safety Standard Part 16 “Power  
Transmission and Distribution,” which is referenced in R 408.41410. This part also  
applies to cut-and-cover excavations which are both physically connected to ongoing  
underground construction operations within the scope of this part and covered in such a  
manner as to create conditions characteristic of underground construction.  
History: 1979 AC; 1993 AACS; 2003 AACS; 2014 AACS.  
R 408.41405 Applicability.  
Rule 1405. These rules apply to auger boring and jacking operations when occupied  
by an employee with the exception of R 408.41463.  
History: 2003 AACS; 2019 AACS.  
R 408.41410 Adoption of standards by reference.  
Rule 1410. (1) The following standards are adopted by reference in these rules and  
are available from the U.S. Government Printing Office Bookstore, 710 North Capitol  
Street N.W., Washington, DC, at the toll-free telephone number: 866-542-1800 or via the  
internet at website: www.ecfr.gov at no cost as of the time of adoption of these rules:  
(a) The provisions of 30 CFR, Mineral Resources Parts 1 to 199 “Mine Safety and  
Health Administration, Department of Labor,” revised July 1, 2000.  
(b) The provisions of 42 CFR, Public Health, Part 84 “Approval of Respiratory  
Protective Devices,” revised October 1, 2001.  
Page 1  
(2) The standards adopted in subrule (1) of this rule are available for inspection at the  
Department of Labor and Economic Opportunity, MIOSHA, Standards and FOIA  
Section, 530 West Allegan Street, P.O. Box 30643, Lansing, Michigan, 48909-8143.  
(3) Copies of the standards adopted in subrule (1) of this rule may be obtained from  
the publisher or may also be obtained from the Department of Labor and Economic  
Opportunity, MIOSHA, Standards and FOIA Section, 530 West Allegan Street, P.O. Box  
30643, Lansing, Michigan, 48909-8143, at the cost charged in this rule, plus $20.00 for  
shipping and handling.  
(4) The following Michigan occupational safety and health administration (MIOSHA)  
standards are referenced in these rules. Up to 5 copies of these standards may be  
obtained at no charge from the Michigan Department of Labor and Economic  
Opportunity, MIOSHA, Standards and FOIA Section, 530 West Allegan Street, P.O. Box  
30643, Lansing, Michigan, 48909-8143; or via the internet at the following website:  
www.michigan.gov/mioshastandards. For quantities greater than 5, the cost, as of the  
time of the adoption of these rules, is 4 cents per page.  
(a) Construction Safety and Health Standard Part 1. “General Rules,” R 408.40101  
to R 408.40134.  
(b) Construction Safety Standard Part 7. “Welding and Cutting,” R 408.40701 to  
R 408.40762.  
(c) Construction Safety Standard Part 9. “Excavation, Trenching, and Shoring,”  
R 408.40901 to R 408.40953.  
(d) Construction Safety and Health Standard Part 10. “Cranes and Derricks,”  
R 408.41001 to R 408.41099a.  
(e) Construction Safety Standard Part 16. “Power Transmission and Distribution,”  
R 408.41601 to R 408.41658.  
(f) Construction Safety Standard Part 17. “Electrical Installations,” R 408.41701 to  
R 408.41734.  
(g) Construction Safety Standard Part 18. “Fire Protection and Prevention,”  
R 408.41801 to R 408.41884.  
(h) Construction Safety and Health Standard Part 21. “Guarding of Walking and  
Working Areas,” R 408.42101 to R 408.42160.  
(i) Construction Safety and Health Standard Part 22. “Signals, Signs, Tags, and  
Barricades,” R 408.42201 to R 408.42243.  
(j) Construction Safety Standard Part 27. “Blasting and Use of Explosives,”  
R 408.42701 to R 408.42799.  
(k) Construction Safety Standard Part 45. “Fall Protection,” R 408.44501 to  
R 408.44502.  
(l) General Industry and Construction Safety and Health Standard Part 451.  
“Respiratory Protection,” R 325.60051 to R 325.60052.  
(m) Construction Safety and Health Standard Part 665. “Underground Construction,  
Caissons, Cofferdams, and Compressed Air,” R 325.62991 to R 325.62996.  
History: 2003 AACS; 2013 AACS; 2014 AACS; 2021 MR 4, Eff. Mar. 2, 2021.  
R 408.41454 Rescinded.  
Page 2  
History: 1979 AC; 1993 AACS; 2003 AACS.  
R 408.41455 Definitions; A to H.  
Rule 1455. (1) "Atmospheric pressure" means the pressure of air at sea level, usually  
14.7 p.s.i.a. (1 atmosphere) or zero p.s.i.g.  
(2) “Auger boring and jacking” means the mechanical removal of soil by use of a  
rotating auger and cutting head and simultaneously installing pipe or other lining where  
the section of lining is installed at the opening of the excavation and is jacked or  
otherwise forced toward the advancing face.  
(3) "Auger tunnel" means a tunnel that is excavated by use of a continuous flight  
auger system, with or without a sleeve or other type of liner.  
(4) "Bulkhead" means an airtight structure separating the working chamber from  
free air or from another chamber under a lesser pressure than the working pressure.  
(5) "Caisson" means either a generally vertical foundation unit below grade or a  
chamber placed in the ground or water for excavating earth and in which it is possible for  
a person to work under air pressure greater than atmospheric pressure to excavate  
material below water level.  
(6) "Cofferdam" means a temporary structure used to control the flow of water and  
other material during construction operations.  
(7) "Competent person" means a person who is experienced and capable of  
identifying existing and predictable hazards in the surroundings or under working  
conditions that are hazardous or dangerous to an employee, and who has the authority  
and knowledge to take prompt corrective measures to eliminate hazards.  
(8) "Compressed air" means an environment that has a pressure greater than  
atmospheric pressure.  
(9) "Decanting" means a method used for decompressing under emergency  
circumstances. In this procedure, the employees are brought to atmospheric pressure with  
a very high gas tension in the tissues and then immediately recompressed in a second and  
separate chamber or lock.  
(10) "Emergency lock" means a lock designed to hold and permit the quick passage  
of an entire shift of employees.  
(11) "Escape-only respirator" means a respirator intended to be used only for  
emergency exit.  
(12) "High air" means air pressure used to supply power to pneumatic tools and  
devices.  
History: 1979 AC; 1989 AACS; 2003 AACS; 2019 AACS.  
R 408.41456 Definitions; M to W.  
Rule 1456. (1) "Man lock" means a chamber through which employees pass from 1  
air pressure environment into another.  
(2) "Materials lock" means a chamber through which  
equipment pass from 1 air pressure environment into another.  
materials  
and  
(3) "Occupied tunnel" means any tunnel entered by 1 or more employees.  
Page 3  
(4) "Pressure" means a force acting on a unit area, usually shown as pounds per  
square inch (p.s.i.).  
(5) "Qualified person" means a person who, by possession of a recognized  
degree, certificate, or professional standing, or who by extensive knowledge, training,  
and experience, has successfully demonstrated the ability to solve or resolve problems  
relating to the subject matter, the work, or the project.  
(6) "Safety screen" means an airtight and watertight diaphragm placed  
vertically across the upper part of a compressed air tunnel between the face and  
bulkhead in order to restrain sudden flooding of the crown of the tunnel between the  
safety screen and the bulkhead, thus providing a means of refuge and exit from a  
flooding or flooded tunnel.  
(7) "Shaft" means a vertical or inclined opening excavated below ground  
level, that is for the purpose of tunnel operations.  
(8) "Tunnel" means a generally horizontal excavation or facility more than l4 inches  
in diameter, width, or height and more than 6 feet in length below ground or water.  
Facilities used for the acquisition of minerals, ores, and fossil fuels, which are  
commonly known as mines, are excluded from this definition.  
(9) "Working chamber" means the space or compartment under air pressure in  
which the work is being done.  
History: 1979 AC; 1984 AACS; 2003 AACS.  
R 408.41461 Advance notice of tunnel excavation.  
Rule 1461. (1) Before the start of a pressurized tunnel being constructed, modified,  
or repaired, that is 24 inches or more in diameter, height, or width, and that will be  
occupied by an employee, a report prepared by the employer performing the tunnel  
excavation shall be sent to the Michigan Department of Labor and Economic  
Opportunity, Construction Safety and Health Division, 530 West Allegan Street, P.O.  
Box 30645, Lansing, Michigan 48909-8145, in addition to the following civil authorities  
in the area: hospital, police department, fire department, and sheriff department. The  
report shall contain all of the following information:  
(a) Name of contractor or contractors.  
(b) Starting date.  
(c) Length of tunnel.  
(d) Diameter of cut.  
(e) Finished diameter.  
(f) Number of shafts.  
(g) Depth of shafts.  
(h) Location of shafts.  
(i) Method of tunneling.  
(j) Maximum working pressure in tunnel or shaft.  
(k) Type of primary liner.  
(l) Number of shifts.  
(m) Projected completion date.  
(n) Projected maximum work force within tunnel.  
Page 4  
(2) An employer shall notify parties notified pursuant to subrule (1) of this rule  
when the work has been completed.  
(3) If, after the start of any tunnel project, a tunnel or shaft that the employer has  
shown to be constructed, modified, or repaired under atmospheric conditions requires the  
tunnel to be pressurized, then the employer shall notify the Construction Safety and  
Health Division at the Michigan Department of Labor and Economic Opportunity, 530  
West Allegan Street, P.O. Box 30645, Lansing, Michigan 48909-8145, 24 hours before  
allowing employees to enter the tunnel.  
(4) If the work operations of any occupied and pressurized tunnel projects are  
discontinued for 30 consecutive days or longer, then the employer shall notify the  
Construction Safety and Health Division at the Michigan Department of Labor and  
Economic Opportunity, 24 hours before resuming work operations on the tunnel project.  
History: 1979 AC; 2003 AACS; 2014 AACS; 2019 AACS; 2021 MR 4, Eff. Mar. 2, 2021.  
R 408.41462 Safety generally.  
Rule 1462. (1) The employer shall inform oncoming shifts of any hazardous  
occurrences or conditions that have affected or might affect employee safety, including  
liberation of gas, equipment failures, earth or rock slides, cave-ins, floodings, fires, or  
explosions.  
(2) A safe means of egress and access to all work areas shall be provided and  
maintained free of hazards.  
(3) When work is not being performed, access to an underground opening shall be  
covered, bulkheaded, fenced off, or restricted by gates or doors and appropriately posted.  
(4) Any section of tunnel that is not in use shall be barricaded to prevent ingress by  
an unauthorized employee.  
(5) Construction of a trench, manhole, or other opening for use in a tunnel or shaft  
operation shall be as prescribed in construction safety standard Part 9. Excavation,  
Trenching, and Shoring and construction safety standard Part 45. Fall Protection, which  
is referenced in R 408.41410.  
(6) An area subject to subsidence that is hazardous to an employee shall be fenced  
and appropriately posted.  
(7) Each operation shall have a check-in and check-out system that will provide  
positive identification of an employee by number or name and will identify the location  
of each employee who is underground. An accurate record shall be kept on the surface.  
However, a check-in and check-out system is not required when the construction of  
underground facilities that are designed for human occupancy has been completed so that  
the permanent environmental controls are effective and the remaining construction  
activity will not cause any environmental hazard or structural failure within the facilities.  
(8) All employees shall be instructed in the recognition and avoidance of hazards  
that are associated with all of the following underground construction activities:  
(a) Air monitoring.  
(b) Ventilation.  
(c) Illumination.  
(d) Communications.  
(e) Flood control.  
Page 5  
(f) Mechanical equipment.  
(g) Personal protective equipment.  
(h) Explosives.  
(i) Fire prevention and protection.  
(j) Emergency procedures, including evacuation plans and check-in and check-out  
systems.  
(9) The employer shall issue each employee a copy of the project’s general safety  
rules before the employee commences work at the project.  
(10) Each employer shall designate a qualified person who is responsible for  
administering the safety program. A written record shall be maintained of the safety  
training program.  
(11) Before an employee enters a tunnel where the atmosphere may be hazardous  
due to a condition such as a deficiency of oxygen, or may be toxic in excess of the  
maximum allowable limits, the tunnel shall be tested and the results shall be recorded as  
prescribed in occupational health standard Part 665. Underground Construction,  
Caissons, Cofferdams, and Compressed Air, which is referenced in R 408.41410. The  
records shall be maintained at the jobsite. If the atmosphere is hazardous, either  
sufficient ventilation to eliminate the hazard shall be provided or respiratory equipment  
as prescribed by the department of licensing and regulatory affairs shall be worn.  
(12) If an atmosphere is found to be explosive, then sparks, flame, and other sources  
of ignition shall be prohibited and ventilation shall be provided until the hazard has been  
reduced and maintained at or below the maximum allowable limits as prescribed by the  
department of licensing and regulatory affairs.  
History: 1979 AC; 1984 AACS; 1993 AACS; 1996 AACS; 2003 AACS; 2013 AACS.  
R 408.41463 Emergency provisions; plans; equipment; rescue crews.  
Rule 1463. (1) The employer shall develop a plan to evacuate a tunnel in an  
emergency and the procedures to carry out the plan shall be made known to the  
employees and to the rescue team.  
(2) An employer shall ensure that rescue teams are familiar with conditions at the  
jobsite.  
(3) On jobsites where 25 or more employees work underground at 1 time, an  
employer shall provide, or make arrangements in advance with locally available rescue  
services to provide, at least 2 5-person rescue teams.  
One of the teams shall be on the jobsite or within 1/2 hour of travel time from the  
entry point and the other team shall be within 2 hours of travel time from the entry point.  
(4) On jobsites where fewer than 25 employees work underground at 1 time, an  
employer shall provide, or make arrangements in advance with locally available rescue  
services to provide, at least 1 5-person rescue team. The team shall either be on the  
jobsite or be within 1/2 hour of travel time from the entry point.  
(5) On jobsites where flammable or noxious gases are encountered or anticipated in  
hazardous quantities, rescue team members shall practice donning and using self-  
contained breathing apparatus monthly.  
(6) An emergency hoisting facility, such as a mud box or a crane, shall be readily  
available at a shaft that is used as a means of egress, unless a hoisting means is provided  
Page 6  
that is independent of an electrical power failure. The hoisting means shall be designed  
so that the load hoist drum is powered in both directions of rotation and so that the brake  
is automatically applied upon power release or failure.  
(7) An employer shall provide an escape-only respirator that is a self-contained  
breathing apparatus with a minimum of a 5 minute air supply. Respirators shall be  
approved by the national institute for occupational safety and health as prescribed in the  
provisions of 42 C.F.R. Public Health Service, Part 84 “Approval of Respiratory  
Protective Devices,” as adopted in R 408.41410. Respirators shall be used in accordance  
with Occupational Health Standard Part 451 “Respiratory Protection,” as referenced in  
R 408.41410. Escape-only respirators shall be immediately available for each employee  
at work stations in underground areas where employees might be trapped by smoke or  
gas.  
(8) Escape-only respirator that is a self-contained breathing apparatus shall be  
maintained in good operating condition. Employees shall be trained in its use.  
(9) The employer shall maintain a rescue crew for each shift of all underground  
operations. The rescue crew shall be trained in rescue procedures, the use and limitations  
of a breathing apparatus, and the use of fire fighting equipment. The crews shall be  
retrained at least once each year. Local fire and police personnel may be used as rescue  
teams for tunnel operations. If local personnel are to be used, then the employer shall  
arrange for assistance before the start of the project.  
(10) The employer shall provide the following minimum rescue equipment at the top  
of the shaft:  
(a) Four units of 1/2-hour-rated, self-contained breathing apparatus.  
(b) Four additional units of 1/2-hour-rated air bottles.  
(c) Four bureau of mines flashlights or lanterns with additional batteries for each  
light. The flashlights shall be as prescribed in part 20 of subchapter B of the provisions  
of 30 C.F.R., Mineral Resources, Parts 1-199 “Mine Safety and Health Administration,  
Department of Labor,” as adopted in R 408.41410.  
(d) Two 2A-10BC fire extinguishers.  
(e) One stretcher, wire basket type or equivalent with slings attached.  
(f) One fire blanket.  
(g) One 10-ton hand hydraulic rescue kit.  
(h) One first aid kit as prescribed in Construction Safety Standard Part 1 “General  
Rules,” as referenced in R 408.41410.  
(11) At least 1 employee shall be on duty above ground when an employee is  
working underground. The primary duty of the employee who is above ground shall be  
to secure immediate aid for an employee who is underground in case of an emergency.  
History: 1979 AC; 1982 AACS; 1993 AACS; 2003 AACS; 2014 AACS.  
R 408.41464 Communication system; location; signals  
Rule 1464. (1) In a tunnel that is more than 225 feet long, the employer shall provide  
a communication system at all of the following locations:  
(a) The working face.  
(b) The top of the shaft.  
(c) The bottom of the shaft.  
Page 7  
(d) The hoisting station, if provided.  
(e) Each 1,000 feet of tunnel.  
(f) The office, if provided. A public telephone or other communication system shall  
be provided or available to each tunnel project to secure outside emergency help.  
(g) Hoist operators shall be provided with a closed-circuit voice communication  
system to each landing station. The system shall have speaker microphones located so  
that the operator can communicate with individual landing stations during hoist use.  
(2) An employer shall establish and maintain direct communications for  
coordination of activities with other employers whose operations at the jobsite affect or  
may affect the safety of employees who are underground.  
(3) If a tunnel is pressurized, then an employer shall provide all of the following  
additional locations with a communication system:  
(a) The working chamber side of the manlock near the door.  
(b) The interior of all locks.  
(c) The lock attendant’s station.  
(d) The compressor plant.  
(e) The first aid station.  
(4) Communication systems shall be tested upon initial entry of each shift to the  
underground, and as often as necessary thereafter, to ensure that they are in working  
order.  
(5) An employee who works alone underground in a hazardous location and who is  
both out of the range of natural unassisted voice communication and not under  
observation by other persons shall be provided with an effective means of obtaining  
assistance in an emergency.  
(6) If a gassy condition exists, then all phones that are located within the tunnel shall  
conform to the United States Bureau of Mines Schedule 9b, Part 23 of the provisions of  
30 C.F.R., Mineral Resources, Parts 1-199 “Mine Safety and Health Administration,  
Department of Labor,” as adopted in R 408.41410. The telephone or other signal  
communication systems shall be independent of the tunnel power supply and shall be  
installed so that the use or disruption of any one phone or signal location will not disrupt  
the operation of the system from any other location.  
History: 1979 AC; 1984 AACS; 1993 AACS; 2003 AACS; 2013 AACS; 2014 AACS.  
R 408.41465 Protective clothing or equipment.  
Rule 1465. An employee working in a wet shaft, tunnel, or caisson shall wear safety  
toe rubber boots which have flat gripper-type soles and which are provided by the  
employer, at no expense to the employee.  
History: 1979 AC; 1982 AACS; 1984 AACS; 2003 AACS; 2013 AACS.  
R 408.41466 Electrical requirements.  
Rule 1466. (1) A power line shall be well separated or insulated from water lines,  
telephone lines, and air lines.  
Page 8  
(2) Lighting circuits shall be located so that the movement of personnel or  
equipment will not damage the circuits or disrupt service.  
(3) Electrical equipment and wiring shall be installed and maintained as prescribed  
in the provisions of subparts F to J of part 77 of the provisions of 30 C.F.R., Mineral  
Resources, Parts 1-199 “Mine Safety and Health Administration, Department of Labor,”  
as adopted in R 408.41410. The provisions of subparts F to J are adopted with the  
following amendments:  
(a) Article 305-1(a) is amended to read as follows: Temporary electrical power and  
lighting installations shall be permitted during the period of construction, remodeling,  
maintenance, repair, or demolition of buildings, structures, equipment, or similar  
activities which are located at ground level and which are part of facilities used for the  
construction of tunnels, shafts, and cofferdams.  
(b) Article 310-15, is amended to read as follows: The maximum continuous  
ampacities for copper, aluminum, and copper-clad aluminum conductors shall be as  
specified in table 310-16 to 310-19 and accompanying notes 1 to 12. Power and lighting  
circuits may be loaded to the maximum design temperatures of the wire or cable  
insulation under the following conditions:  
(i) A means shall be provided to disconnect the load if the feeder cable exceeds  
design temperature by more than 10% for 1 minute.  
(ii) Power cable shall have a grounding and a pilot wire that conforms to the  
Insulated Power Cable Engineers Association (IPCEA) type G grounded cable (G-GC) or  
equivalent.  
(iii) Power cable shall have a loose connector emergency shutdown ability.  
(iv) Power cable shall have a ground fault emergency shutdown ability.  
(v) Power cable shall have an arc between phases emergency shutdown ability.  
(c) Oil filled transformers shall not be used underground unless they are located in a  
fire-resistant enclosure suitably vented to the outside and surrounded by a dike to retain  
the contents of the transformer in the event of rupture.  
(4) All electrical power circuits that supply portable or hand-held tools, lights, or  
equipment shall be protected by approved ground-fault interrupters as prescribed in  
Construction Safety Standard Part 17 “Electrical Installations,” as referenced in  
R 408.41410.  
(5) The regular system of illumination shall be supplemented by lighting that can be  
activated upon the failure of the regular system. Supplemental lighting, such as approved  
flashlights or lanterns, shall be sufficient to allow all employees to evacuate the tunnel.  
(6) Electrical installation in underground areas where oil, grease, or diesel fuel are  
stored shall be used only for lighting fixtures.  
(7) Lighting fixtures in storage areas, or within 25 feet (7.62 meters) of underground  
areas where oil, grease, or diesel fuel are stored, shall be approved for class I, division 2  
locations, as prescribed in Construction Safety Standard Part 17 “Electrical Installations,”  
as referenced in R 408.41410.  
History: 1993 AACS; 2003 AACS; 2013 AACS; 2014 AACS.  
R 408.41467 Fire prevention and protection.  
Page 9  
Rule 1467. (1) The applicable requirements for fire prevention and protection as  
prescribed in Construction Safety Standard Part 18. “Fire Prevention and Protection,” as  
referenced in R 408.41410, shall be complied with in all tunnel and shaft operations.  
(2) Smoking and open flames are prohibited. An employer is responsible for  
collecting all personal sources of ignition, such as matches and lighters, from all persons.  
Welding and cutting, where required, shall comply with the provisions of subrules (9) to  
(14) of this rule. A fire watch shall be maintained when hot work is performed.  
(3) Not more than a 1-day supply of diesel fuel shall be stored in a tunnel or shaft.  
Gasoline or liquefied petroleum gas shall not be taken in a tunnel or shaft. Acetylene or  
methylacetylene propadiene stabilized gas may be used underground solely for welding,  
cutting, and other hot work and only as prescribed in Construction Safety Standard Part 7.  
“Welding and Cutting,” as referenced in R 408.41410.  
(4) The piping of diesel fuel from the surface to an underground location is  
permitted only if all of the following provisions are complied with:  
(a) Diesel fuel is contained at the surface in a tank with a maximum capacity that is  
not more than the amount of fuel required to supply, for a 24-hour period, the equipment  
that is serviced by the underground fueling station.  
(b) The surface tank is connected to the underground fueling station by an  
acceptable pipe or hose system that is controlled at the surface by a valve and at the shaft  
bottom by a hose nozzle.  
(c) The pipe is empty at all times, except when transferring diesel fuel from the  
surface tank to a piece of equipment in use underground.  
(d) Hoisting operations in the shaft are suspended during refueling operations if the  
supply piping in the shaft is not protected from damage.  
(e) Acetylene, liquefied petroleum gas, and methylacetylene propadiene stabilized  
gas may be used underground only for welding, cutting, and other hot work and only in  
accordance with subrules (9) to (14) of this rule.  
(f) Not more than the amount of fuel gas and oxygen cylinders necessary to perform  
welding, cutting, or other hot work during the next 24-hour period shall be permitted  
underground.  
(5) Leaks and spills of flammable or combustible fluids shall be cleaned up  
immediately.  
(6) Oil, grease, or diesel fuel that is stored in a tunnel or shaft shall be kept in tightly  
sealed containers in fire-resistant areas at safe distances from explosives, magazines,  
electrical installations, and shaft stations. Electrical installations in underground areas  
where oil, grease, or diesel fuel are stored shall be used only for lighting fixtures.  
Lighting fixtures in storage areas, or within 25 feet (7.62 meters) of underground areas  
where oil, grease, or diesel fuel are stored, shall be approved for class I, division 2  
locations.  
(7) Fire-resistant hydraulic fluids shall be used in hydraulically actuated  
underground machinery and equipment. For the purpose of this requirement, a fire-  
resistant hydraulic fluid means any liquid which has a flash point above 200 degrees  
Fahrenheit and which has a vapor pressure of not more than 40 p.s.i. (absolute) at 100  
degrees Fahrenheit.  
(8) An approved 4A:40B:C rating fire extinguisher or equivalent protection shall be  
provided at the drive pulley of an underground conveyor and at 300-foot intervals along  
Page 10  
the belt. A minimum of 2 2A-10BC approved fire extinguishers shall be provided at the  
tunneling machine.  
(9) Internal combustion engines, except diesel-powered engines on mobile  
equipment, are prohibited underground.  
(10) Mobile diesel-powered equipment used underground in atmospheres other than  
gassy operations:  
(a) Shall comply with MSHA provisions in 30 CFR 57.5067; or  
(b) If purchased on or before July 15, 2019, may alternatively comply with MSHA  
provisions under 30 CFR part 32 (revised as of July 1, 1996) (formerly Schedule 24), or  
be demonstrated by the employer to be fully equivalent to such MSHA-approved  
equipment, and be operated in accordance with that part.  
(11) For purposes of subrules (9) and (10) of this rule, when an applicable MSHA  
provision uses the term “mine,” use the phrase “underground construction site.” (Each  
brake horsepower of a diesel engine requires at least 100 cubic feet (2.832 m3) of air per  
minute for suitable operation in addition to the air requirements for personnel. Some  
engines may require a greater amount of air to ensure that the allowable levels of carbon  
monoxide, nitric oxide, and nitrogen dioxide are not exceeded.)  
(12) Fire-resistant hydraulic fluids shall be used in hydraulically-actuated  
underground machinery and equipment unless such equipment is protected by a fire  
suppression system or by multipurpose fire extinguisher or fire extinguishers of sufficient  
capacity for the type and size of hydraulic equipment involved, but rated at least  
4A:40B:C.  
(13) A noncombustible barrier shall be installed below welding or burning  
operations.  
(14) In an underground operation, local gas checks shall be made before and during  
a welding or cutting operation and during a drilling operation that would penetrate the  
tunnel.  
(15) Whenever 5% or more of the lower explosive limit for methane or other  
flammable gases is detected in any underground work area or in the air return, an  
employer shall take steps to increase ventilation air volume or otherwise control the gas  
concentration, unless the employer is operating in accordance with the potentially gassy  
or gassy operation requirements. Such additional ventilation controls may be  
discontinued when gas concentrations are reduced below 5% of the lower explosive limit,  
but shall be reinstituted whenever the 5% level is exceeded.  
(16) Whenever 10% or more of the lower explosive limit for methane or other  
flammable gases is detected in the vicinity of welding, cutting, or other hot work, such  
work shall be suspended until the concentration of such flammable gas is reduced to less  
than 10% of the lower explosive limit.  
(17) A fire watch shall be maintained around welding and cutting operations until all  
possibility of fire is eliminated. The fire watch shall be provided with a minimum of 1  
approved 2A-10BC fire extinguisher.  
(18) Flammable materials or supplies, other than those used during 1 shift, shall not  
be stored within 100 feet (30.48 meters) of any tunnel or shaft opening. If this is not  
feasible because of space limitations on the jobsite, then such materials may be located  
within the 100 foot limit, if both of the following provisions are complied with:  
(a) The materials are located as far as practicable from the opening.  
Page 11  
(b) A fire resistant barrier of not less than a 1-hour rating is placed between the  
stored material and the opening or additional precautions are taken that will protect the  
materials from ignition sources.  
History: 1993 AACS; 2003 AACS; 2013 AACS; 2014 AACS; 2021 MR 4, Eff. Mar. 2, 2021.  
R 408.41468 Rescinded.  
History: 1979 AC; 2013 AACS.  
TUNNELS AND SHAFTS  
R 408.41471 Ground support; inspections; repairs.  
Rule 1471. (1) A qualified employee shall inspect the roof, face, and walls of  
portals, work areas, and haulage ways, or travel-ways at the start of each shift and  
frequently thereafter as needed. If loose soil or rock or fractured material is encountered,  
then it shall be scaled or protected and supported. The employee conducting the  
inspections shall be protected from loose ground by location, ground support, or  
equivalent means. Suitable protection shall be provided for employees exposed to the  
hazard of loose ground while installing ground support systems. Support sets shall be  
installed so that the bottoms have sufficient anchorage to prevent ground pressures from  
dislodging the support base of the sets. Lateral bracing (collar bracing, tie rods, or  
spreaders) shall be provided between immediately adjacent sets to ensure added stability.  
Damaged or dislodged ground supports that create a hazardous condition shall be  
promptly repaired or replaced. When replacing supports, the new supports shall be  
installed before the damaged supports are removed. A shield or other type of support  
shall be used to maintain a safe travel way for employees working in dead-end areas  
ahead of any support replacement operation.  
(2) A scaling bar shall be in good condition. A blunted or severely worn bar shall  
not be used.  
(3) A torque meter and a torque wrench shall be available where rock bolts are used  
for ground support. Frequent tests shall be made to determine if the bolts are tight. The  
test frequency shall be determined by rock conditions and distance from vibration  
sources.  
(4) A damaged or dislodged tunnel support shall be repaired or replaced when  
structural integrity is impaired. A new support shall be installed if possible before  
removing damaged supports.  
(5) Tunnel supports shall be designed and installed to prevent pressure from pushing  
them inward into the excavation.  
(6) Roof supports shall be used where ground conditions are such that there could be  
a ground failure ahead of tunnel sets.  
(7) A tunnel that is to be occupied by employees shall be provided with a steel  
casing, concrete pipe, timber, or other material of required strength to support the  
surrounding earth.  
Page 12  
(8) If an employee is required to enter a tunnel or an auger boring and jacking  
operation less than 3 feet in diameter, then a lifeline for instant rescue shall be securely  
fastened to his or her ankles. Another employee shall be stationed at the tunnel entrance  
to operate the lifeline. In addition, ventilation shall be provided with an air line.  
History: 1979 AC; 2003 AACS; 2019 AACS.  
R 408.41472 Shafts; supports; inspections; lifelines.  
Rule 1472. (1) A shaft that an employee is required to enter shall be provided with  
steel casing, concrete pipe, timber, or other material that is strong enough to support the  
surrounding earth.  
(2) A shaft that is more than 5 feet in depth shall be braced to support the  
surrounding earth. The bracing shall be provided the full depth of the shaft, or, if rock is  
encountered, to not less than 5 feet into solid rock, and shall extend not less than 1 foot  
above the ground level.  
(3) After a blasting operation, the bracing shall be inspected. If the bracing is found  
to be unsafe, then corrections shall be made before the shift operations are continued.  
(4) A shaft or caisson shall be protected with a guardrail system as prescribed in  
Construction Safety Standard Part 45 “Fall Protection,” as referenced in R 408.41410, or  
barricaded as prescribed in Construction Safety Standard Part 22 “Signals, Signs, Tags,  
and Barricades,” as referenced in R 408.41410. A gate opening into the shaft shall be  
provided and shall be closed at all times, except when necessary to enter or leave the  
shaft or caisson.  
History: 1979 AC; 1982 AACS; 1984 AACS; 1996 AACS; 2003 AACS; 2013 AACS; 2014 AACS.  
R 408.41473 Drilling; inspection; jumbos.  
Rule 1473. (1) Drilling equipment that is to be used during  
a
shift shall be  
inspected each shift by a qualified employee. Equipment defects affecting safety shall  
be corrected before the equipment is used.  
(2) The drilling area shall be inspected for hazards before starting the drilling  
operation.  
(3) An employee shall not be allowed on a drill mast while the drill is in operation.  
(4) When a drill is moved from one area to another, drill steel, tools, and other  
equipment shall be secured, and the mast shall be placed in a safe position.  
(5) Drills on columns or stiff legs shall be anchored firmly before drilling is  
started and they shall be retightened frequently thereafter.  
(6) A jumbo deck more than 5 feet high shall be provided with guardrails on all open  
sides and on the back platform. A stair or ladder access, wide enough for 2  
employees, shall be provided to a jumbo deck 10 feet or more in height.  
(7) A jumbo deck, ladders, and stairs shall be kept clean to prevent the hazard of  
slipping and tripping. The deck shall be an anti-slip type and the deck shall be secured  
to prevent displacement.  
Page 13  
(8) A mechanical means shall be provided for lifting drills, roof bolts, mine straps,  
and other unwieldy heavy material to the top deck of a jumbo more than 10 feet in  
height.  
(9) Receptacles or racks shall be provided for drill steel stored on a jumbo.  
(10) When a jumbo is moved, a rider shall not be allowed on the jumbo unless  
the employee is assisting the operator.  
(11) Jumbo wheels shall be chocked while an employee is working on the jumbo.  
(12) Before the drilling cycle is started, a warning shall be given to employees  
working under jumbo decks.  
(13) Before commencing a drilling cycle, the face and lifters shall be examined  
for misfires. If found, the misfired explosive shall be removed before the drilling  
starts. A lifter shall not be drilled through a blasted muck pile.  
(14) An air line that is buried in the invert shall be identified by signs posted  
nearby warning all employees.  
History: 1979 AC.  
R 408.41474 Blasting.  
Rule 1474. (1) All blasting and explosives handling shall be conducted as prescribed  
in Construction Safety Standard Part 27 “Blasting and Use of Explosives,” as referenced  
in R 408.41410.  
(2) An employer shall not allow an employee to enter a shaft or a tunnel heading  
after blasting until air quality meets minimum requirements.  
(3) Blasting wire shall be kept clear of electrical lines, pipes, rails, and other  
conductive material, excluding earth, to prevent explosives initiation or employee  
exposure to electric current.  
(4) After blasting operations in shafts, a competent person shall determine if the  
walls, ladders, timbers, blocking, or wedges have loosened. If so, necessary repairs shall  
be made before employees other than those assigned to make the repairs are allowed in or  
below the affected areas.  
History: 1979 AC; 2003 AACS; 2014 AACS.  
R 408.41475 Haulage; inspection; braking; riding.  
Rule 1475. (1) Haulage equipment that is to be used during a shift shall be inspected  
by a qualified person before the start of the shift. Known defects that affect the safety of  
employees shall be corrected before the equipment is used.  
(2) A powered locomotive or other mobile equipment shall be provided with suitable  
brakes, an audible warning device for use by the operator as needed, and lights at both  
ends.  
(3) Powered mobile haulage equipment that is subject to falling materials shall be  
equipped with a cab, canopy, or other protective device that is capable of protecting the  
operator from shifting or falling materials. For cabs where glazing is used, the glass shall  
be safety glass, or its equivalent, and shall be maintained and cleaned so that vision is not  
obstructed.  
Page 14  
(4) Powered mobile equipment shall not be left unattended unless the power is off,  
all operating controls are in the neutral position, and the brakes are set or other equivalent  
precautions are taken to prevent rolling. The operating controls shall be designed to  
automatically return to a neutral position or shall be equipped with a deadman control.  
(5) Backstops or automatic braking shall be installed on an inclined conveyor to  
prevent the conveyor from running out of control and creating a hazard for the employee.  
(6) An employee shall not ride on either of the following unless specifically  
designed or adapted for transporting employees:  
(a) A power-driven chain, belt, or bucket conveyor.  
(b) Haulage equipment. An employee shall not ride haulage equipment unless it is  
equipped with seating for each passenger and protects passengers from being struck,  
crushed, or caught between other equipment or surfaces.  
(7) An employer shall not use an endless belt-type man lift in underground  
construction.  
(8) Cars that are dumped by hand shall be provided with tie-down chains or dumper  
blocks to prevent the cars from overturning.  
(9) A rocker bottom or bottom-dump car shall be equipped with positive-locking  
devices.  
(10) Equipment that is to be hauled shall be loaded or protected so as to prevent  
sliding or spillage.  
(11) Parked rail haulage equipment shall be chocked or chained if subject to  
accidental movement.  
(12) Berms, bumper blocks, safety hooks, or similar means shall be provided to  
prevent overtravel or overturning at dumping locations and, where necessary, at track  
dead ends.  
(13) Supplies, materials, and tools, other than small hand tools, shall not be  
transported with employees in the same car and shall not be transported on top of a  
locomotive.  
(14) A train that is used on an incline which would cause the cars to run out of  
control shall, in addition to couplings, have safety chains, or the equivalent, to connect  
the cars and the power haulage equipment in a train. The safety chains or other  
connections shall be capable of maintaining connection between cars in the event of  
coupler disconnect, failure, or breakage.  
(15) When an employee is being transported in a train, the operator shall have clear  
vision beyond the forward end of the train for safe operation.  
(16) Mobile equipment, including rail-mounted equipment, shall be stopped for  
manual connecting or service work.  
(17) Employees shall not reach between moving cars during coupling operations.  
(18) Couplings shall not be aligned, shifted, or cleaned when cars or locomotives are  
moving.  
(19) Where switching facilities are available, occupied personnel cars shall be  
pulled, not pushed. If occupied personnel cars must be pushed and the visibility of the  
track is hampered, then a qualified person shall be stationed in the lead car to give signals  
to the locomotive operator.  
History: 1979 AC; 1984 AACS; 1993 AACS; 2003 AACS; 2013 AACS; 2014 AACS.  
Page 15  
R 408.41475a Hoisting unique to underground construction.  
Rule 1475a. Except as modified by this standard, employers shall comply with all of  
the following:  
(a) The requirements of Construction Safety and Health Standard Part 10. “Cranes  
and Derricks,” as referenced in R 408.41410,  
(b) Ensure that material hoists comply with Construction Safety and Health Standard  
Part 10. “Cranes and Derricks,” as referenced in R 408.41410.  
(c) Ensure that personnel hoists comply with the personnel hoists requirements of  
Construction Safety and Health Standard Part 10. “Cranes and Derricks,” as referenced in  
R 408.41410.  
History: 2013 AACS; 2014 AACS; 2021 MR 4, Eff. Mar. 2, 2021.  
R 408.41476 General requirements for cranes and hoists.  
Rule 1476. (1) A competent person shall check each safety device at least weekly  
during hoist use to ensure suitable operation and safe condition.  
(2) Before hoisting personnel or material, the operator shall perform a test run of any  
cage or skip whenever it has been out of service for one complete shift, and whenever the  
assembly or components have been repaired or adjusted.  
(3) An employee shall not ride on a material hoist, unless the hoist is in compliance  
with the requirements of R 408.41478(1).  
(4) Before maintenance, repairs, or other work is commenced in the shaft that is  
served by a hoist, the hoist operator shall be informed of the maintenance, repairs, or  
other work and given suitable instructions. A sign warning that work is being done in the  
shaft shall be installed at the shaft collar, at the operator’s station, and at each  
underground landing.  
(5) Employees who are at the bottom of an excavated shaft shall be protected from  
the movement of equipment, tools, or materials overhead or the shaft shall be vacated  
during the operations that may be hazardous to persons below.  
(6) If an employee is raised or lowered in a shaft, then all other hoisting operations  
in the shaft shall be stopped until the employee has disembarked at the bottom or top of  
the shaft.  
(7) When a stationary hoist is being used, the drum-operating lever shall be of a type  
that returns automatically to the “stop” position when the operator’s hand is removed,  
unless, as a substitute, the throttle that controls the drum speed automatically stops the  
drum and slows the engine to idling speed when the throttle is released.  
(8) Only wire rope shall be used for hoisting and it shall be properly secured at both  
the drum and cage or skip ends. When the hoist is in use, not less than 2 full turns shall  
remain on the conventional drum hoist to protect the end that fastens at the drum from an  
overload.  
(9) The connection between the hoisting rope and the cage or skip shall be of a type  
to prevent the cage from spinning.  
(10) All hoists shall be equipped with a landing level indicator at the operator’s  
station. Marking the hoist rope does not satisfy this requirement.  
(11) Limit switches shall be used only to limit travel of loads when operational  
controls malfunction and shall not be used as a substitute for other operational controls.  
Page 16  
(12) A warning light, suitably located to warn employees at the shaft bottom and  
subsurface shaft entrances, shall flash if a load is above the shaft bottom or subsurface  
entrances or if the load is being moved in the shaft. This subrule does not apply to fully  
enclosed hoistways.  
(13) If a hoistway is not fully enclosed and employees are at the shaft bottom, then  
conveyances or equipment shall be stopped not less than 15 feet above the bottom of the  
shaft and held there until the signalperson at the bottom of the shaft directs the operator to  
continue lowering the load, except that the load may be lowered without stopping if the  
load or conveyance is within full view of a bottom signalperson who is in constant voice  
communication with the operator.  
(14) Cage, skips, and load connections to the hoist rope shall be made so that the  
force of the hoist pull, vibration, misalignment, release of lift force, or impact will not  
disengage the connection. Moused or latched open-throat hooks do not meet this  
requirement.  
(15) When using wire rope wedge sockets, means shall be provided to prevent  
wedge escapement and to ensure that the wedge is properly seated.  
(16) Hoists shall be designed so that the load hoist-drum is powered in both  
directions of rotation and so that the brakes are automatically applied upon power release  
or failure.  
(17) When a hoist is used for both personnel hoisting and material hoisting, the load  
and speed ratings for personnel and for materials shall be assigned to the equipment.  
(18) Employees shall not ride on top of any cage, skip, or bucket, except when  
necessary to perform inspection or maintenance of the hoisting system, in which case  
they shall be protected by a body belt/harness fall prevention system.  
(19) Material, tools, and supplies being raised or lowered, whether within a cage or  
otherwise, shall be secured or stacked in a manner to prevent the load from shifting,  
snagging, or falling into the shaft.  
(20) Any connection between the hoisting rope and the cage or skip shall be  
compatible with the type of wire rope used for hoisting.  
(21) Spin-type connections, where used, shall be maintained in a clean condition and  
protected from foreign matter that could affect their operation.  
History: 1979 AC; 1984 AACS; 1993 AACS; 2003 AACS; 2013 AACS; 2014 AACS.  
R 408.41477 Additional requirements for hoists.  
Rule 1477. (1) A hoist used for raising or lowering materials in a shaft shall have a  
minimum factor of safety of 5, shall be designed and rated by a qualified engineer, and  
shall be constructed in accordance with the design. The design shall be constructed so  
that the hoist cannot exceed the maximum rated speed.  
(2) The rated capacity of the hoist shall be posted at all working levels.  
(3) To ensure suitable operation and safe condition of all functions and safety  
devices, each hoist assembly shall be inspected and load-tested to 100% of its rated  
capacity at the time of installation; after any repairs or alterations affecting its structural  
integrity; after the operation of any safety device; and annually when in use. The  
employer shall prepare a certification record which includes the date each inspection and  
load-test was performed; the signature of the person who performed the inspection and  
Page 17  
test; and a serial number or other identifier for the hoist that was inspected and tested.  
The most recent certification record shall be maintained on file until completion of the  
project.  
(4) A competent person designated by the employer shall visually inspect the  
stationary hoist assembly, anchorages, and hoisting rope at the beginning of each shift.  
(5) All unsafe conditions that are revealed by tests, checks, or inspections shall be  
corrected before use of the equipment.  
(6) Hoist equipment and the operator shall be protected from inclement weather by a  
hoist house with a comfortable temperature maintained.  
(7) Where glass is used in hoist house windows, the glass shall be safety glass or its  
equivalent.  
(8) Hoist controls shall be arranged so that the operator can perform all operating  
cycle functions and reach the emergency power cutoff without having to reach beyond  
the operator’s normal operating position.  
(9) Controls for powered hoists shall be of the deadman-type with a non-locking  
switch or control.  
(10) All hoists shall be equipped with landing level indicators at the operator’s  
station. Marking the hoist rope does not satisfy this requirement.  
(11) Material hoisting may be performed at speeds higher than the rated speed for  
personnel hoisting if the hoist and components have been designed for such higher speeds  
and if shaft conditions permit.  
(12) Personnel and materials (other than small tools and supplies secured in a  
manner that will not create a hazard to employees) shall not be hoisted together in the  
same conveyance. However, if the operator is protected from the shifting of materials,  
then the operator may ride with materials in cages or skips which are designed to be  
controlled by an operator within the cage or skip.  
(13) Line speed shall not exceed the design limitations of the systems.  
(14) A fire extinguisher that is rated at least 2A:10B:C, multi-purpose, dry chemical,  
shall be mounted in each hoist house.  
(15) Hoists shall be equipped with limit switches to prevent overtravel at the top and  
bottom of the hoistway.  
(16) Hoist operators shall be provided with a closed-circuit voice communication  
system to each landing station, with speaker microphones located so that the operator can  
communicate with individual landing stations during hoist use.  
(17) When sinking shafts 75 feet (22.86 m) or less in depth, cages, skips, and  
buckets that may swing, bump, or snag against shaft sides or other structural protrusions  
shall be guided by fenders, rails, ropes, or a combination of those means.  
(18) When sinking shafts more than 75 feet (22.86 m) in depth, all cages, skips, and  
buckets shall be rope or rail guided to within a rail length from the sinking operation.  
(19) Cages, skips, and buckets in all completed shafts, or in all shafts being used as  
completed shafts, shall be rope or rail-guided for the full length of their travel.  
(20) Wire rope used in load lines of material hoists shall be capable of supporting,  
without failure, at least 5 times the maximum intended load or the factor recommended  
by the rope manufacturer, whichever is greater. Refer to Construction Safety and Health  
Standard Part 10. “Cranes and Derricks,” as referenced in R 408.41410, for design factors  
for wire rope used in personnel hoists. The design factor shall be calculated by dividing  
Page 18  
the breaking strength of wire rope, as reported in the manufacturer's rating tables, by the  
total static load, including the weight of the wire rope in the shaft when fully extended.  
History: 1979 AC; 2003 AACS; 2013 AACS; 2014 AACS; 2021 MR 4, Eff. Mar. 2, 2021.  
R 408.41477a Additional requirements for cranes.  
Rule 1477a. Cranes shall be equipped with a limit switch to prevent overtravel at the  
boom tip. Limit switches are to be used only to limit travel of loads when operational  
controls malfunction and shall not be used as a substitute for other operational controls.  
History: 2013 AACS.  
R 408.41478 Additional requirements for personnel hoists.  
Rule 1478. (1) A personnel hoist shall be used to raise or lower an employee in a  
tunnel shaft or caisson. A crane may be used to raise or lower an employee, if the crane  
and the work platform are as prescribed in Construction Safety and Health Standard Part  
10. “Cranes and Derricks,” as referenced in R 408.41410. The hoist shall comply with  
1967 PA 227, MCL 408.801 to 408.824, and the elevator safety rules of the Bureau of  
Construction Codes, Elevator Safety Board, R 408.7001 to R 408.8695.  
(2) All sides of personnel cages shall be enclosed by 1/2-inch (12.70 mm) wire  
mesh, at least no. 14 gauge or its equivalent, to a height of at least 6 feet (1.83 m). When  
the cage or skip is being used as a work platform, its sides may be reduced in height to 42  
inches (1.07 m) when the conveyance is not in motion. All personnel cages shall be  
provided with a positive-locking door that only opens inward.  
(3) Flammable or combustible liquids or gases shall not be permitted on the work  
platform if the platform is occupied by an employee or employees.  
(4) Hoist drum systems shall be equipped with at least 2 means of stopping the load,  
each of which shall be capable of stopping and holding 150 % of the hoist’s rated line  
pull. A broken-rope safety, safety catch, or arrestment device is not a permissible means  
of stopping.  
(5) The operator shall remain within sight and sound of the signals at the operator’s  
station.  
(6) All personnel cages shall be provided with a protective canopy. The canopy shall  
be made of steel plate, at least 3/16-inch (4.763 mm) in thickness, or material of  
equivalent strength and impact resistance. The canopy shall be sloped to the outside, and  
so designed that a section may be readily pushed upward to afford emergency egress. The  
canopy shall cover the top in such a manner as to protect those inside from objects falling  
in the shaft.  
(7) Personnel platforms operating on guide rails or guide ropes shall be equipped  
with broken-rope safety devices, safety catches or arrestment devices that will stop and  
hold 150 % of the weight of the personnel platform and its maximum rates load.  
(8) During sinking operations in shafts where guides and safeties are not yet used,  
the travel speed of the personnel platform shall not exceed 200 feet (60.96 m) per minute.  
Governor controls set for 200 feet (60.96 m) per minute shall be installed in the control  
system and shall be used during personnel hoisting.  
Page 19  
(9) The personnel platform may travel over the controlled length of the hoistway at  
rated speeds up to 600 feet (182.88 m) per minute during sinking operations in shafts  
where guides and safeties are used.  
(10) The personnel platform may travel at rated speeds greater than 600 feet  
(182.88m) per minute in completed shafts.  
History: 1979 AC; 1984 AACS; 1993 AACS; 1996 AACS; 2003 AACS; 2013 AACS; 2014 AACS;  
2021 MR 4, Eff. Mar. 2, 2021.  
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.  
History: 1979 AC; 1984 AACS; 1996 AACS; 2003 AACS; 2014 AACS.  
COFFERDAMS AND CAISSONS  
R 408.41481 Cofferdams.  
Rule 1481. (1) A cofferdam shall be designed by a qualified engineer and shall be  
constructed and maintained in accordance with the design.  
(2) If overtopping of the cofferdam by high waters is possible, then means shall be  
provided for controlled flooding of the work area.  
(3) The employer shall develop and post warning signals for the evacuation of  
employees in case of an emergency.  
(4) A cofferdam shall have not less than 2 means of egress.  
Runways, bridges, or ramps shall be provided with guardrails as prescribed in  
Construction Safety Standard Part 45 “Fall Protection,” as referenced in R 408.41410.  
(5) If cofferdams are located close to navigable shipping channels, then warning  
devices that are visible to vessels in transit shall be provided.  
History: 1979 AC; 1984 AACS; 1996 AACS; 2003 AACS; 2014 AACS.  
Page 20  
R 408.41482 Caisson excavation; employee protection.  
Rule 1482. (1) An employee who enters a caisson shall be protected by a steel or  
concrete casing designed by a qualified employee and approved by a registered engineer.  
(2) A copy of the design specifications of the casing shall be maintained at the  
jobsite.  
(3) In the case of belled-bottom caissons, the steel or concrete casing shall be  
provided for the full depth of that part of each caisson hole that is above the bell.  
(4) An employer shall not permit an employee to work below the casing in running  
or unstable soil.  
(5) The steel or concrete caisson shall extend not less than 12 inches above the  
ground line.  
(6) Each employee who is required to enter a caisson excavation shall have a lanyard  
attached to a body harness and to the load line of a crane. The attachment to the load line  
shall utilize a screwpin shackle.  
(7) An employee whose lanyard is attached to the load line of a crane shall be  
permitted to be lowered to the bottom of the caisson in the muck bucket.  
(8) The maximum rate of travel when lowering an employee shall be 100 feet per  
minute. Free-spooling when lowering employees into a caisson is prohibited.  
(9) All employees shall be removed from the caisson when material is being hoisted  
from the caisson.  
(10) A secondary mechanical means that is capable of removing an employee from  
the caisson shall be readily available in case the crane performing the caisson work  
breaks down.  
(11) A top person shall be stationed at the caisson and shall constantly monitor any  
employees who are in the caisson.  
(12) A positive means of communication shall be maintained between employees  
working in the caisson and the top person.  
(13) The air quality of a caisson shall be tested and maintained in accordance with  
Occupational Health Standard Part 665 “Underground Construction, Caissons,  
Cofferdams, and Compressed Air,” as referenced in R 408.41410.  
(14) Where space permits, a caisson shall have a stairway for its entire height and  
shall have landing platforms not more than 20 feet apart. Where this is impracticable, a  
ladder shall be installed and landing platforms shall be located not more than 20 feet  
apart to break the climb.  
History: 1979 AC; 1984 AACS; 1996 AACS; 2013 AACS; 2014 AACS.  
R 408.41483 Caissons used under pressure.  
Rule 1483. (1) A caisson used under pressure shall be subjected to a hydrostatic test  
equal to 200% of the working pressure before being used on a job, at which pressure it  
shall be tight. The caisson shall be stamped on the outside shell about 12 inches from  
each flange to show the pressure to which it has been subjected.  
(2) All caissons that have a diameter or side greater than 10 feet shall be provided  
with a man lock and shaft for the exclusive use of employees. In addition to the gauge in  
the locks, an accurate gauge shall be maintained on the outer and inner side of each  
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bulkhead. These gauges shall be accessible at all times and kept in accurate working  
order.  
(3) In caisson operations where employees are exposed to compressed air working  
environments, employers shall comply with Occupational Health Standard Part 665  
“Underground Construction, Caissons, Cofferdams, and Compressed Air,” as referenced  
in R 408.41410.  
History: 1989 AACS; 2003 AACS; 2014 AACS.  
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