“It’s all good now,” their foreman announces,”but we’ll still be monitoring, so be careful.” Coolers in hand, hard hats andfluorescent vests reflecting the glare of the light towers, they clomp downseven flights of stairs into a large open pit, shored up by wooden timbers andcrowded with vats of grout, portable trailers and man lifts.
The mouth of thetunnel gapes at them. The moon, the clouds and the city disappear as theyenter. In 2021, commuters will follow their steps, barreling through anS-shaped tunnel — the $1.75-billion Regional Connector project — 1.9 miles outof Little Tokyo, north to Bunker Hill and west to 7th and Flower streets, atransit corridor that will link Long Beach to Azusa and Santa Monica to EastL.A.
Construction workers will lay almost a mile of that tunnel through amethodical excavation of Flower Street, building the subway and then rebuildingthe street. The rest, however, is being dug the hard way. The miners, traipsingsingle file along a plank walkway, descend a gentle grade into the tunnel fornearly half a mile before reaching their destination: a 400-foot-long,1,000-ton earth-chewing beast, known as the tunnel boring machine. Sometimescalled moles, sometimes sandhogs, the men — there are no women on this shift —belong to a tight confederacy. They can see themselves doing little else for aliving. They like being left alone to do their job. They like the variety ofchallenges, the on-the-spot repairs. They like the community.
“There are no badpeople down here,” said one miner. “We would throw them out if there were.” Veteransof other tunnels, they have built passages for water to flow through the SanBernardino Mountains and under Lake Mead, and they look ahead to thepossibility of digging beneath the streets of South Pasadena or in theSacramento-San Joaquin Delta. For those willing to travel, the world is inplay.
Tunnels are turning Earth into an ant farm with massive projects underwayin London, New York, Hong Kong and Germany. In Qatar, nearly 24 tunnelingmachines are digging a subway system for the 2022 World Cup, and in China, onecompany manufactures nearly 50 tunneling machines a year for that market alone.As long as the world’s population continues to grow and cities become morecongested, there will be a demand for tunnels and miners, says Richard McLane,chief mechanical engineer for the Regional Connector Project. “Why is tunnelingso addicting?” McLane asks. “It’s like watching civilization in action. This isnot a leaf spring for a Chevy Camaro that in 10 years will be in a junkyard.The work we do will last generations.
” After a five-minute walk through thetunnel, the miners reach their destination and begin to spread out. Inside theoperator’s cab, a small air-conditioned box near the front of the tunnelingmachine, Scott Halsey faces a wall of monitors, one featuring video feeds ofthe conveyor belts, others relaying with rising and falling numbers themachine’s progress. His hands are reflexively poised over rows of switches,dials, toggles and buttons lit red or green.
He picks up the phone. Lookingmore like a computer technician than a miner, Halsey presses a series ofbuttons, and the numbers on the control panel begin to rise. Seventy feetahead, far out of sight, the machine’s cutting head has begun to rotate. Hydraulicjacks push the cutting head forward and exert a steady pressure against theearth. The cutting head grinds through the earth at two rotations a minute,shaving and clawing at a dense wall of clay and silt compressed over millennia.Every minute it advances three inches. Auger screws churn the excavated soil —softened by a foamy mixture of air, conditioner and water to a Play-Doh-likesubstance known as muck — and conveyor belts transport it back to the pit andan armada of dump trucks bound for Irwindale. The high-pitch whir of thecutting head echoes inside the tunneling machine along with the drone of theconveyor belts, motors driving the hydraulics, the hammering of the greasepumps and the occasional air-horn blast from an arriving locomotive that runsthrough the tunnel ferrying supplies and equipment.
Halsey first stood at thisconsole in 2004 when he took his inaugural run into Boyle Heights underMariachi Plaza for the Gold Line. Never having operated equipment so demanding,he remembers shaking with adrenaline. He and his wife live on a cul-de-sac inSanta Clarita, but he has done his share of traveling for the job, mostrecently to Washington where he experienced history from 130 feet deep,tunneling under the Potomac River (“that George Washington crossed”) and nearthe airfield where Obama’s helicopter was hangared. That soil, he says, was thebest he has ever found: clay with layers of sand. Halsey is a member of theInternational Union of Operating Engineers Local 12 and earns nearly $50 anhour, not counting overtime. He got his start in tunnels almost 20 years agowhen he was in his early 30s, having worked road maintenance after graduatingfrom Sylmar High School. With its heavy machinery, cranes, loaders andexcavators, the underground world was a big kid’s dream, he says. But the workcould be hazardous.
Carbon monoxide and diesel soot choked tunnels. Cave-insleft men running for their lives, and bosses cut corners as they drove theircrews harder and faster. The ancient Persians pioneered tunneling techniquesfor transporting water, and the Romans added fire-quenching — heatingsubterranean rock with fire and dousing it with cold water to encouragecracking — to the engineer’s repertoire. Los Angeles was once considered anunlikely place for such grand ambitions, the soil deemed too gassy, toounpredictable. A methane explosion in a water tunnel in Sylmar in 1971 killed17 miners. In 1985, underground gas accumulated in a clothing store at 3rd andFairfax streets, and when it blew up, nearly two dozen people were injured,leaving many to question the wisdom of building a regional subway system. Gaswasn’t the only problem for the city’s first underground.
In 1994 as Red Linecrews burrowed beneath Hollywood, its star-studded boulevard sank 10 inches,and two years later, the 101 Freeway dropped nearly four. Not long after, a newstyle of tunneling machine came on the scene as the Metropolitan TransitAuthority built the Gold Line.By keeping steady pressure on the earth while excavating, operatorsminimized subsidence and heaving — sinking and bulging — the twin evils oftunneling, and with the miners enclosed in a capsule the diameter of thetunnel, dangerous gases could more easily be vented. With the old equipment,the ground might move as much as an inch and a half, McLane says. On thisproject, he says, sensors have picked up movement of no more than 0.16 inches. After20 minutes, Halsey has excavated five feet.
He pushes a button on the consolelabeled “Ringbuilding,” and Jesus Ruiz and his crew take over. Sixprefabricated segments — up to 8,000 pounds each — have been hauled into thetunnel by a locomotive, and Ruiz, operating the erector, a circular crane thatmoves like the hands of a clock, positions the segments and a keystone aroundthe circumference of the tunnel. “Retract,” shouts a ring builder, and Ruiztoggles a joystick on the remote hanging off his chest, bringing a segment intoalignment. Moving gracefully, each step orchestrated by habit, the minersscramble over and under the erector, leveraging themselves against a network ofladders, catwalks, angle irons and tread plates.
Impact guns slam segment boltsinto the adjoining segments, and after 20 minutes, they are done. Halsey canstart mining again. So it goes for each 10-hour shift, this back-and-forthbetween mining and ring building. Some miners extend water lines, electricalconduits, ventilation duct and tracks for the locomotive.
Another oversees acontinuous injection of grout between the rings and the tunnel boring machine. Thisis the excitement of the job, says Halsey: moving along without interruption.”This is what gets my blood going.” By 8 a.
m., they have built three rings, andthe city above them — drivers rushing to work, cubicle jockeys jaywalking forlattes — is unaware of the activity underfoot. Standing at the console, thumband forefinger on the dials, Halsey monitors the balance between the amount ofdirt the machine excavates and the amount of dirt that, according to McLane’scalculation, can be removed with the minimum of subsidence. If one exceeds theother, the whole enterprise could come to a stop. Halsey makes smalladjustments, but he also knows that the earth can be fickle. At this depth andlocation, it has at times become sticky and gummed up the screw augers thatcarry the muck to the conveyor belts.
“It’s all about what Mother Nature throwsat you.” Mother Nature was not kind to them during the first month of tunnelingas they clawed through the sand and gravel deposits of the ancient floodplainof the Los Angeles River. Five feet took them nearly two and a half hours asthey advanced under the Japanese Village Plaza in Little Tokyo. Whenthey finally hit the silt and clay, a stratum of earth known as the FernandoFormation, they broke out in song. ABBA provided the melody: By then they wereunder 2nd Street with few obstacles in their way.
Up ahead, at Hill Street,they will come within six feet of the Red Line tunnel, and as they close in onthe station at 2nd and Hope streets, they will have a target to hit and can beoff by no more than four inches. The Romans drilled vertical shafts at closeintervals and used plumb lines to keep their tunnels going where they wanted. Alaser navigation system keeps the city’s miners on track. Halsey fine-tunes thepitch and the yaw of the tunneling machine by moderating the pressure appliedby the hydraulic jacks. Early afternoon, and the work has assumed an easyrhythm.
A dusty haze drifts through the tunnel. The miners fill water bottlesfrom Igloo coolers and grab foil-wrapped plates of chicken or leftoverspaghetti that they’d been warming on the electric motors that drive thehydraulics. After replacing a gasket on the erector, repairing an overheadcrane, cleaning a clogged port for the grout and clearing an overloaded ho