The Georgia Department of Transportation expects to reopen I-85 in Buckhead by June 15 – just 11 weeks after a fire caused a section of highway to collapse.

The state will use a mix off financial incentives, expensive materials and round-the-clock work to expedite the work, GDOT officials said at a press conference Tuesday. It will also forego an environmental review and bypass its normal procurement process as it tries to restore a vital transportation artery into the heart of Atlanta.

And while the final price tag is unknown, the federal government will pick up almost all of the tab, GDOT officials said.

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RELATED: How the I-85 closure will affect your commute

Meanwhile, the National Transportation Safety Board is investigating the fire that caused the bridge to collapse last Thursday. And GDOT has asked the State Insurance Commissioner Ralph Hudgens and State Fire Marshall Dwayne Garriss to review GDOT’s procedures for storing materials, especially under bridges.

Last week's fire – allegedly started by a homeless man – was fed by construction material GDOT stored under the I-85 bridge. But GDOT Commissioner Russell McMurry said Tuesday the agency could not have anticipated the fire that led to the bridge collapse.

The bridge demolition is nearly 80 percent completed and will take about 10-weeks to rebuild.

“I don’t think anybody would have ever thought this kind of thing would happen,” he said.

At Tuesday’s press conference, state officials offered the most detailed look yet at the steps they’re taking to rebuild a section of highway traveled by 250,000 people daily.

The inability to use it has forced motorists onto other roads – traffic on I-285 and I-75 is up 50 to 70 percent since the bridge collapse. Local roads also are packed – Cheshire Bridge Road normally carries about 18,000 vehicles per day, but has seen 40,000 a day since I-85 closed, according to GDOT.

Agency officials said those commuting headaches are a big reason they want to expedite rebuilding a stretch of I-85 at Piedmont Road that’s longer than a football field.

To do that, GDOT has skipped an environmental review for a project that will largely be built within the existing footprint of the highway.

It has also bypassed its normal procurement process – including advertising the project and awarding it to the lowest bidder – and has chosen contractor C.W. Matthews to rebuild the interstate. The decision to skip formal bidding was made possible when Gov. Nathan Deal declared a state of emergency last week.

GDOT Construction Director Marc Mastrondardi said the agency wanted a contractor with the capacity to do the work. He said the agency was pleased with the C.W. Matthew’s performance on a similar project in 2001, when a fire shut down part of I-285 over Ga. 400.

“We’re in coordination with GDOT and the June 15 date is achievable,” said Dan Garcia, president of C.W. Matthews.

Garcia said the Marietta-based company will work this project “24/7 with multiple crews.” Some 30 to 40 workers will be on site each shift.

Demolition at the site will be completed by the end of this week, he said.

GDOT also is hustling. It has completed the design of the new highway section and forwarded the plans to the contractor early Monday.

To speed up construction, the agency decided to use quick-curing concrete. It’s an expensive product the state doesn’t normally use, but it will expedite construction, McMurry said.

Though details are still being negotiated, C.W. Matthews would receive a bonus if it finishes the project by June 15 and for every day before then the project is completed.

“As happens in private business, we want to incentivize an even earlier completion,” McMurry said.

Garcia does not anticipate running into anything that could delay the process, but he stressed that “everybody’s got to work in synch.” That includes the main contractor, subcontractors, suppliers and state transportation officials.

While work on the new bridge continues, federal and local authorities continue to investigate the cause of the fire. McMurry said GDOT is cooperating with the NTSB and with the Atlanta Fire Department.

He’s also asked the insurance commissioner and fire marshal to review GDOT’s storage practices. McMurry said GDOT has not violated any of its policies by storing the construction material under the bridge, though “if there’s anything that needs to be changed, we’ll certainly do so.”

McMurry also has notified transportation officials in other states so they can examine their own policies.

“Obviously, this is a catastrophe of national significance,” he said. “We never would want something like this to happen again.”