While NHL players average 40 to 45 seconds per shift on ice about 20 times during a three-period game, the 140-some construction workers at the New Arena site are divided into day and night shifts this fall, going all-out over five days Monday through Friday with some additional weekend work.

SEATTLE -- The sport of ice hockey is powered by work shifts; it seems only fitting that the building of the New Arena at Seattle Center be too.

The day side is finishing up the construction of 70-plus temporary steel columns that will secure the landmark roof, plus continuing the removal of concrete under 32 buttresses that formerly held up the iconic arena top designed as part of the 1962 World's Fair.

"We're almost there with the temporary roof support," says Ken Johnsen, construction executive for the Oak View Group and NHL Seattle.

Other daytime work includes ongoing excavation of 600,000 total cubic yards of dirt, attaching scaffolding to the underside of the iconic roof and lining the outer rectangular perimeter of the construction site with shoring walls that will eventually descend as far as 70 feet below ground.

"The excavation crew is moving the dirt into piles so the night shift can haul it away," says Johnsen. "We're hauling about 5,000 cubic yards each night."

The hole that will house the New Arena gets bigger every shift.

"Every day I come in here, I am amazed," says Johnsen. "I remember less than a month ago, we could just get our hands under the Y-columns' steel rebar and the dirt below. Now the dirt is 20 to 30 feet lower down."

There are also shoring walls installed for a major tunnel to be dug in earnest during November. The tunnel will become the entry point for trucks coming and going from eight underground world-class loading docks for the new arena. The dedicated tunnel and those next-gen docks will be a major feature to attract the biggest musical acts, which travel anywhere from a dozen to 80 semi-trailer trucks to put on high-tech, high-entertainment from venue to venue.

The inner roof will be fully covered with scaffolding in time.

"This is a unique project," explains Johnsen. "Normally you have a crane that works to build the roof. We have to work on the underside of the roof. Rather than set up a crane in there, we're building scaffolding on the entire roof.

The night hauling involves loading trucks at two locations, southeast and north. By November's end, conveyor belts will automate a part of the process and load trucks in three locations.

The trucks then take the dirt to three local sites that want the dirt for their own projects, "one south and two to the north," says Johnsen.

As a part of the new arena work, the original glass that was installed in the building in 1962 was removed, numbered and cataloged earlier this year. It is stored at a warehouse in Kent. Oak View Group's lead construction partner, Mortenson, is currently testing the glass and its framing.

"We demolished the bowl, but we did not demolish the glass and steel mullions that will keep the glass in place," says Johnsen. "We actually set up a mockup that shows how to put the glass back in place."

The mockup allows workers to additionally make sure the glass will be secure, fits correctly, caulked right and weatherproof.

"When people walk up [in 2021] and see the roof and that glass, it will bring back good memories," says Johnsen. "Then they will walk in to see a brand-new bowl, and a brand-new arena."