Alabama Tunnel Contractor Examination

OSHA 29 CFR 1926.800 Underground Construction applies to which of the following operations?

• AAny open trench for a building footing that is not connected to a tunnel
• BConstruction of underground tunnels, shafts, chambers, and passageways, including cut-and…
• COnly finished tunnels after the lining is complete and mining has stopped
• DUnderground electrical transmission and distribution line work covered by Subpart V

Which statement best describes microtunneling as used in ASCE construction guidelines?

• AAn open-face hand-mined heading that miners enter on every shove
• BA drill-and-blast rock tunnel advanced by heading and bench
• CA remotely controlled, guided, pipe-jacked operation with a continuously supported face,…
• DA surface cut-and-cover box built from the top down

In tunnel terminology, which definitions are correct?

• AInvert is the floor, crown is the top, and springline is the mid-height at the sides
• BInvert is the top of the lining, crown is the floor, and springline is the shaft collar
• CInvert is the TBM cutterhead, crown is the muck skip, and springline is the laser
• DInvert is the access shaft, crown is the reception shaft, and springline is the jacking f…

When is cut-and-cover tunneling typically selected?

• AFor deep rock tunnels far below existing streets
• BOnly when a slurry TBM cannot be delivered to the site
• COnly for vertical shafts, never for horizontal tunnels or stations
• DFor relatively shallow tunnels or stations that can be excavated from the surface, built…

In tunneling, what is muck?

• AGrout injected behind a segmental lining
• BExcavated material removed from the heading by rail, conveyor, slurry circuit, or similar…
• CCompressed air used to hold a soft-ground face
• DThe steel skin of a shielded TBM

How does pipe jacking advance the product pipe?

• ABy pulling the pipe string from the reception shaft with a winch only
• BBy floating the pipe into an open trench and then backfilling
• CBy hydraulic jacks in a drive shaft that push pipe strings behind the shield or machine;…
• DBy spinning the pipe as an auger that remains in the ground as the product

What is the primary purpose of probe drilling ahead of a tunnel face?

• ATo detect water, voids, or gas before the heading advances into them
• BTo replace survey control so lasers are no longer needed
• CTo measure concrete slump in the invert pour
• DTo determine the legal One-Call ticket expiration date

What lining is typically erected immediately behind a shielded TBM in soft ground?

• AOnly timber sets with no rings
• BUnreinforced brick laid from the surface
• CA poured invert placed before the TBM is launched
• DPrecast concrete segmental rings, often with gaskets for watertightness

On a mined tunnel project, shafts are most commonly used for which combination of functions?

• AOnly as finished passenger stations
• BAccess, muck removal, ventilation, and hoisting, with temporary lining as required
• COnly to store unused explosives at the face
• DOnly as a location for the concrete batch plant mixer drum

Under OSHA 1926.800, which statement about open flames underground is correct?

• AOpen fires are allowed anywhere underground as long as self-rescuers are issued
• BGasoline-fueled open-flame heaters are the preferred method to dry a heading
• COpen flames and fires are prohibited underground except permitted welding, cutting, or ot…
• DOpen flames are prohibited only in gassy headings and are unrestricted elsewhere

How must unused underground openings be treated under OSHA 1926.800?

• AThey must be tightly covered, bulkheaded, or fenced and posted with "Keep Out" or similar…
• BThey may be left open if a cone is placed at the portal
• CThey need only be noted on the as-built drawings after final completion
• DThey must be painted orange and left accessible as emergency refuge rooms

Which TBM choice is most appropriate in soft ground where face pressure must be controlled to limit settlement?

• AAn open-face or gripper TBM intended for competent rock
• BAn earth-pressure-balance (EPB) or slurry TBM that can maintain face pressure
• CA roadheader with no face support in running sand below the water table
• DDrill-and-blast with no temporary support

Why are intermediate jacking stations installed on a long pipe-jack or microtunnel drive?

• ATo replace the need for a reception shaft
• BTo increase the cutterhead diameter after launch
• CTo ventilate the drive shaft only
• DTo distribute jacking force along the pipe string so the capacity of the pipe and the mai…

Which description best matches NATM or the sequential excavation method (SEM)?

• AAn observational method that uses shotcrete, rock bolts or lattice girders, and instrumen…
• BA remotely controlled slurry microtunnel that no one enters
• CA cut-and-cover box excavated full-width from the street with no instrumentation
• DA method that forbids any temporary support until the final lining is poured

What is the usual production cycle for a drill-and-blast rock tunnel?

• APour final lining, then drill, then blast through the new concrete
• BBlast first with no drilling, then immediately place the final lining before ventilating
• CDrill the round, load explosives, blast, ventilate, muck, then install support; larger he…
• DJack pipe rings from the surface after each blast without mucking

What is the purpose of ground freezing as a tunnel or shaft ground-control method?

• ATo heat the face so shotcrete never needs curing
• BTo temporarily strengthen and cut off groundwater by freezing pore water into an ice-soil…
• CTo replace the need for any lining after the ice melts
• DTo classify the heading as gassy under OSHA

What does jet grouting do when used for tunnel or shaft ground control?

• AIt only paints the ground surface to mark the alignment
• BIt replaces the TBM cutterhead with a grout pump
• CIt is used only to color-code One-Call marks
• DIt erodes soil with a high-pressure grout jet and mixes the soil with grout to form treat…

Why are elastomeric gaskets specified on precast tunnel segments?

• ATo provide watertightness at the segment joints when the rings are bolted or expanded
• BTo replace annular grout behind the rings
• CTo increase the TBM cutterhead torque
• DTo mark the invert so surveyors can see the crown

Which systems are commonly used to keep a TBM or microtunnel on line and grade?

• AGuessing heading from surface traffic noise
• BSpirit level on the muck skip only
• CLaser, total-station, or gyro guidance, with invert grade especially critical on gravity-…
• DMagnetic compass alone, without a designed alignment

During pipe jacking or auger boring, when employees enter the casing while it is being constructed, which OSHA requirement applies according to OSHA interpretation?

• AOnly the general duty clause; no construction standard applies
• BSubpart S underground construction requirements apply to that entry
• COnly Subpart V electrical T&D rules apply
• DEntry is forbidden in all casings regardless of diameter or procedure

Why is ground-settlement monitoring specified near buildings and utilities above a soft-ground tunnel?

• ATo replace face-pressure control on an EPB machine
• BTo determine the OSHA gassy classification
• CTo set the legal One-Call ticket length
• DTo detect movement with surface points, inclinometers, or similar instruments so the cont…

Under OSHA 1926.800, what communication is required when natural unassisted voice is ineffective underground?

• APower-assisted voice communication between the face, shaft bottom, and surface; shafts us…
• BHand signals only, with no voice system allowed
• CA single whistle at the portal that is never tested
• DCell phones only, with no backup if service is lost

An employee will work alone underground in a hazardous location, out of unassisted voice range and not observed. What does OSHA 1926.800 require?

• ANothing additional, because a lone worker is exempt from underground rules
• BOnly a written note left on the skip
• CAn effective means of obtaining emergency assistance
• DThat the worker leave self-rescue equipment at the portal

What information must be given to an oncoming underground shift under OSHA 1926.800?

• AOnly the coffee-break schedule
• BHazardous occurrences such as gas, equipment failures, slides, cave-ins, flooding, fires,…
• COnly the next week's concrete ticket times
• DNothing, because each shift starts with a clean slate

What is the purpose of the OSHA 1926.800 check-in/check-out system?

• ATo bill extra hours to the owner automatically
• BTo replace atmospheric testing at the face
• CTo keep muck cars from entering the shaft
• DTo allow aboveground personnel to determine the number of persons underground in an emerg…

Whenever anyone is underground, OSHA 1926.800 requires which aboveground staffing?

• AAt least one designated person on duty above ground who keeps an accurate count and is no…
• BNo aboveground person if radios are issued
• CA full five-person rescue team sitting idle at every lunch box, regardless of crew size
• DOnly a security guard who is forbidden to keep a head count

Where employees might be trapped by smoke or gas, which respiratory devices must be immediately available underground?

• AAny hardware-store dust mask
• BOnly a shared air horn at the portal
• CSelf-rescuers approved by NIOSH under 42 CFR 84
• DScuba tanks intended for recreational diving only

What is the construction purpose of dewatering around a tunnel or shaft?

• ATo increase the natural groundwater table before mining
• BTo lower groundwater and improve stability or reduce inflow so excavation and lining can…
• CTo classify the heading as gassy
• DTo replace ventilation after a blast

Why is invert grade especially critical on a gravity drainage or sewer tunnel?

• ABecause a high invert automatically increases hoop compression in the lining
• BBecause grade has no effect on flow if the pipe is circular
• CBecause OSHA requires every invert to be level
• DBecause flow depends on designed downward slope; a high or low invert can create sags, re…

If 25 or more employees are underground at one time, what rescue-team capability does OSHA 1926.800 require?

• ANo rescue team if self-rescuers are issued
• BOne two-person first-aid crew at the home office
• CAt least two five-person teams, one on site or within one-half hour and the other within…
• DOnly a designated aboveground counter, with no rescue team

When must an underground operation be classified as potentially gassy under OSHA 1926.800?

• AWhen 10 percent or more of the LEL for methane or other flammable gas is measured 12 inch…
• BWhen oxygen falls to 20.9 percent, the normal outdoor value
• COnly after an ignition has already occurred
• DWhenever any trace of carbon dioxide is present

Which condition requires classifying an underground operation as gassy under OSHA 1926.800?

• AA single 5 percent LEL reading that is immediately ventilated below 5 percent
• BSpoil piled more than 2 feet from a surface trench
• CUse of a laser for TBM guidance
• D10 percent or more of the LEL for three consecutive days, or ignition of methane or flamm…

When may a gassy underground operation be declassified to potentially gassy under OSHA 1926.800?

• AAs soon as one handheld reading is below 20 percent of the LEL
• BWhen flammable gas stays under 10 percent of the LEL for three consecutive days
• CAfter any lunch break if no one smells gas
• DOnly after the tunnel is fully lined and the contract is closed

A monitor in an underground work area or the air return reaches 20 percent or more of the LEL. What must happen immediately?

• AContinue mining but issue extra dust masks
• BOnly suspend welding if it is already in progress, and keep all other power on
• CWithdraw employees to a safe location above ground and cut electrical power except accept…
• DIncrease only the muck-train speed to clear the heading

A rapid excavation machine is used in an operation classified as potentially gassy. Under OSHA 1926.800, where must the continuous automatic flammable-gas monitoring equipment sample, and what must happen at 20 percent or more of the LEL?

• AAt the heading, on the rib, and in the return air duct, with the monitor signaling the he…
• BA single monitor at the surface office that only logs data overnight
• CMonitors only on the muck skip, with no power shutdown at any LEL
• DNo monitors if the machine is electric

A gravity tunnel invert is elevation 214.80 feet at Station 12+00 and elevation 212.40 feet at Station 16+00. What is the invert slope?

• A0.24 percent downward
• B0.60 percent downward
• C1.20 percent downward
• D2.40 percent downward

A circular tunnel heading is 8 feet in excavated diameter and 250 feet long. Using 3.14 for pi, what is the excavated volume in cubic yards?

• A186 cubic yards
• B233 cubic yards
• C349 cubic yards
• D465 cubic yards

Unless a retaining device is used, how far from the edge of an excavation must spoil, materials, and equipment be kept under OSHA Subpart P?

• AAt least 6 inches
• BAt least 2 feet
• CAt least 10 feet in every soil type
• DNo setback is required if the spoil is Type C

In a surface excavation, when is a protective system required under OSHA 1926.652?

• AAt 5 feet of depth or deeper, unless a competent person finds no indication of a potentia…
• BOnly at 20 feet or deeper
• CNever in Type A soil
• DOnly if employees will sleep in the trench

For an excavation less than 20 feet deep in Type C soil, what is the maximum allowable slope in OSHA Subpart P Appendix B?

• AVertical (90 degrees)
• B3/4 horizontal to 1 vertical (53 degrees)
• C1-1/2 horizontal to 1 vertical (34 degrees)
• D1/2 horizontal to 1 vertical (63 degrees)

A cohesive soil has an unconfined compressive strength of 1.8 tsf, but it is fissured and a vibratory roller is working next to the shaft. How should it be classified for OSHA sloping?

• AStable rock
• BType A, because 1.8 tsf exceeds 1.5 tsf
• CType A short-term regardless of vibration
• DNot Type A; fissuring and vibration remove Type A status even if strength is 1.5 tsf or g…

A launch-shaft excavation will be 24 feet deep. Who must design the protective system?

• AAny laborer who has seen a trench box
• BA registered professional engineer
• CThe concrete finisher after the invert is poured
• DNo design is required below 20 feet if the soil is dry

When must a competent person inspect a surface excavation under OSHA 1926.651?

• AOnly on the day the job starts
• BOnly after a fatality
• CDaily, and also after every rainstorm or other occurrence that could increase hazards
• DOnly when OSHA is known to be on site

Before employees enter a surface excavation more than 4 feet deep where oxygen deficiency or a hazardous atmosphere could reasonably be expected, what must be done?

• AThe atmosphere must be tested before entry
• BOnly a visual look from the bank is required
• CTesting is required only if the excavation is more than 20 feet deep
• DEmployees may enter first and test after 15 minutes

A rectangular shaft pit is 180 feet long, 6 feet wide, and 8 feet deep. What is the neat excavation volume in cubic yards?

• A80 cubic yards
• B160 cubic yards
• C240 cubic yards
• D320 cubic yards

A 12-foot-deep excavation in Type C soil is sloped at the OSHA maximum of 1-1/2:1. The bottom width is 8 feet. What is the required top width?

• A20 feet
• B44 feet
• C26 feet
• D12 feet