The Aggravating Adventures of a Gigantic Tunnel Drill
About 20 workers wearing hard hats and reflective vests clump together on the edge of a chasm near Seattle’s waterfront, peering down a hole 120 feet deep and 83 feet wide. The last men have been craned out of the pit in a yellow metal cage. Gulls squawk. A TV news helicopter hovers overhead.
A dozen journalists stand nearby on the bed of a truck. We’re here to see Bertha, one of the world’s biggest tunneling machines. Or at least a piece of her. A 240-foot crane is about to haul a 540,000-pound steel shield out of the ground, 20 months after Bertha started digging a highway. Almost imperceptibly, the crane starts rising.
The event, on a Thursday in mid-March, is part of a massive rescue mission to fix the $80 million machine. She broke abruptly in December 2013 after boring through just 1,000 feet, one-ninth of her job. Her seals busted, and her teeth clogged with grit and pieces of an 8-inch steel pipe left over from old groundwater tests. She stopped entirely.
The tunnel, with a budget of $1.4 billion and originally scheduled to be finished in November 2015, is two years behind schedule. The state’s contractor, a joint venture called Seattle Tunnel Partners (STP), has spent months digging to reach Bertha and crane her to the surface, where a weary Seattle awaits.
Bertha’s job is to bury a highway that runs on a structurally unsound elevated road smack in the middle of an earthquake zone. The viaduct, as it’s called, follows the shoreline, effectively barricading downtown Seattle from what could be a beautiful waterfront. The tunnel will let most of the traffic travel deep underground; at street level an old freeway will be demolished, and in its place the city will build a boulevard and shoreline park created by the designers behind New York’s acclaimed High Line park. The $4.2 billion plan calls for the long-neglected waterfront to come to life; Seattleites can celebrate the glory of Puget Sound, where ferries dash across the bay and the jagged peaks of the Olympic Peninsula jut in the distance.
Everything about the project is gargantuan, starting with Bertha, who is as tall as a five-story building. She runs on a 25,000-horsepower motor and has a head weighing 1.7 million pounds, with 260 steel teeth designed specifically to chew through Seattle’s silty soil. She’s named after the city’s first and only female mayor, Bertha Knight Landes, who served in the 1920s. According to the machine’s official state biography, her role models include “whoever invented the shovel.” Bertha’s got 15,700 Twitter followers, has inspired Halloween costumes, and was once feted by thousands.
After Bertha got stuck, she couldn’t back up because she builds the concrete walls of the tunnel as she drills forward. That means the hole she leaves behind is narrower than she is. The contractor has devised a method—itself unprecedented—to repair Bertha by craning her in sections to the surface. After almost a decade of debating the tunnel’s merits and three more years of construction, more than a few Seattleites argue that Bertha should be buried where she is, her last rites read, and another plan pursued.
About 20 workers wearing hard hats and reflective vests clump together on the edge of a chasm near Seattle’s waterfront, peering down a hole 120 feet deep and 83 feet wide. The last men have been craned out of the pit in a yellow metal cage. Gulls squawk. A TV news helicopter hovers overhead.
A dozen journalists stand nearby on the bed of a truck. We’re here to see Bertha, one of the world’s biggest tunneling machines. Or at least a piece of her. A 240-foot crane is about to haul a 540,000-pound steel shield out of the ground, 20 months after Bertha started digging a highway. Almost imperceptibly, the crane starts rising.The event, on a Thursday in mid-March, is part of a massive rescue mission to fix the $80 million machine. She broke abruptly in December 2013 after boring through just 1,000 feet, one-ninth of her job. Her seals busted, and her teeth clogged with grit and pieces of an 8-inch steel pipe left over from old groundwater tests. She stopped entirely.
The tunnel, with a budget of $1.4 billion and originally scheduled to be finished in November 2015, is two years behind schedule. The state’s contractor, a joint venture called Seattle Tunnel Partners (STP), has spent months digging to reach Bertha and crane her to the surface, where a weary Seattle awaits.
Bertha’s job is to bury a highway that runs on a structurally unsound elevated road smack in the middle of an earthquake zone. The viaduct, as it’s called, follows the shoreline, effectively barricading downtown Seattle from what could be a beautiful waterfront. The tunnel will let most of the traffic travel deep underground; at street level an old freeway will be demolished, and in its place the city will build a boulevard and shoreline park created by the designers behind New York’s acclaimed High Line park. The $4.2 billion plan calls for the long-neglected waterfront to come to life; Seattleites can celebrate the glory of Puget Sound, where ferries dash across the bay and the jagged peaks of the Olympic Peninsula jut in the distance.
Everything about the project is gargantuan, starting with Bertha, who is as tall as a five-story building. She runs on a 25,000-horsepower motor and has a head weighing 1.7 million pounds, with 260 steel teeth designed specifically to chew through Seattle’s silty soil. She’s named after the city’s first and only female mayor, Bertha Knight Landes, who served in the 1920s. According to the machine’s official state biography, her role models include “whoever invented the shovel.” Bertha’s got 15,700 Twitter followers, has inspired Halloween costumes, and was once feted by thousands.
After Bertha got stuck, she couldn’t back up because she builds the concrete walls of the tunnel as she drills forward. That means the hole she leaves behind is narrower than she is. The contractor has devised a method—itself unprecedented—to repair Bertha by craning her in sections to the surface. After almost a decade of debating the tunnel’s merits and three more years of construction, more than a few Seattleites argue that Bertha should be buried where she is, her last rites read, and another plan pursued.
by Karen Weise, Bloomberg | Read more:
Image: Ted S. Warren / AP Photo
