Bertha is more than halfway through its dig under the Alaskan Way Viaduct — and churning ahead more smoothly than South End traffic during the viaduct shutdown.

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Update:

As of 8 p.m. Friday, Bertha had excavated 234 feet.

Update:

As of 11 a.m. Friday, Bertha had excavated 214 feet.

Update:

As of 4 a.m. Friday, Bertha has traveled 208 feet, taking the tunnel-boring machine past the halfway mark in its journey beneath the Alaskan Way Viaduct.

Original post:

Tunnel-boring machine Bertha is about half done with its dig under the Alaskan Way Viaduct, sustaining a pace that a lead contractor says is “better than expected.”

As of 11 a.m. Thursday, the machine dug 182 feet of the 385 feet, or 47 percent of the distance needed to clear the viaduct.

When that milestone is reached, Bertha would be far enough that permanent tunnel rings are completed beneath the viaduct. And the old highway can reopen to the about 120,000 drivers and transit riders who are temporarily detouring or canceling trips.

Soon, the spinning cutter will pass within 15 feet of the nearest viaduct column foundation, where Yesler Way meets the waterfront.

“The reports show the machine is operating as intended and meeting … performance expectations. The viaduct and the ground around the viaduct remain stable,” said Dave Sowers, deputy Highway 99 administrator for the Washington State Department of Transportation.

Odds are improving that the viaduct phase, which began Friday, can be done within the two-week estimate by Seattle Tunnel Partners (STP), a joint venture of California-based Tutor-Perini and Spanish company Dragados USA.

Bertha currently is running 24 hours a day.  No stoppages are planned in the next few days, Sowers said, unless brief maintenance needs arise, such as cleaning clogs where Bertha sprays grout into the surrounding soil to prevent soil settlement.

Ron Tutor, president of Tutor-Perini, said the company expects to conclude the whole dig from Sodo to South Lake Union by December.

“I might add that to date, our tunneling has gone better than expected, as we expect to clear the viaduct sometime next week,” Tutor said, in his quarterly conference call Wednesday with stock analysts. After the dig, Bertha will be extracted near Seattle Center, while construction workers follow behind to complete road decks, lighting, signals and utilities.

Barring future problems, the four-lane tolled Highway 99 tunnel might open in spring 2018. It’s more than two years behind the schedule to open in December 2015, after a late 2013 machine breakdown and extensive repairs.

As for traffic, the Seattle Department of Transportation (SDOT) says it’s dealing with three problems that emerged this week:

• Port trucks added congestion Thursday morning on East Marginal Way, and the city is asking the port to revert to the 3 a.m. start times for loading at Terminal 46 used earlier this week.

• Drivers are clogging or darting into the bus lane on lower Avalon Way Southwest. Jon Layzer, SDOT director of interagency operations, said parking-enforcement officers would be sent to sweep the area Friday morning. The agency saw no need to stretch the lane farther uphill by banning parking, he said.

• Train traffic, a gate malfunction and a truck in the trackway have created delays in Sodo. Layzer said the city asked BNSF Railway to avoid lengthy train-assembly operations at peak times, but so far the railroad hasn’t agreed. Early evening crossings caused similar aggravation during a viaduct closure in 2011, but drivers in 2016 have one more option, to go up the ramp from First Avenue South to the West Seattle Bridge.

BNSF spokesman Gus Melonas said later, “We are making every attempt to minimize blocking these crossings for more than 10 minutes at a time.” However, the railroad is not going to reduce operating hours. Freight time is already at a premium, he said, because Amtrak and Sounder passenger trains, as well as track maintenance, limit the hours available per day.

Freeway traffic has flowed reasonably in many areas, but South End trips into Seattle remain miserable — exceeding 70 minutes from SeaTac to downtown Thursday morning.