Poor Bertha. The giant tunnel-boring machine is at the heart of a US$3.1 billion project that is producing a sinking feeling—among neighboring buildings. Now, the ambitious endeavor in Seattle, Washington, USA has become a very public lesson in all that can go wrong in a project.
“This is like a nightmare you don’t wake up from,” city council member Nick Licata told the Seattle Weekly.
The project plan included building a highway tunnel under the city of Seattle using the world’s largest boring machine, named Bertha. Once the tunnel was complete, an aging elevated viaduct—no longer deemed steadfast against future earthquakes—would be demolished, opening the city’s waterfront. Yet when the tunnel-boring machine’s bearings became clogged with grit just 10 percent into the two-mile (1.6-kilometer) dig, the team struggled to find a fix. Bertha got stuck—and stayed stuck for more than a year.
“The only thing that’s stopped on the job is the actual tunnel boring itself,” project manager Chris Dixon told Popular Mechanics. “Everything else is going ahead full speed.” The project team was reshuffled to minimize work-stop losses: A team, for instance, began work on a multistory subterranean building that houses controls for signals, airflow and sprinklers, while others on the team were tasked with figuring out how to get Bertha to budge.
The repair project—now underway—to get the original project moving again involves building a 12-story pit to reach the machine. But that digging may be causing damage, including masonry cracks, to nearby buildings in the downtown area. In December, project engineers announced that more than 30 buildings had unexpectedly settled by as much as 1 inch (2.5 centimeters), possibly because of project-related water pumping.
A view from the back end of the tunneling machine, looking toward the tunnel’s entrance
City stakeholders have been vocal in their concerns, demanding reassurances that a fix is on the horizon. But Washington Department of Transportation officials have warned that a new end date for the project, originally slated to be complete in 2015, is impossible to estimate until a fix for Bertha is found. —M. Wright
FEBRUARY 2015 PM NETWORK