Work crews will need about $2 million and fewer than six months to replace the 110-foot bridge destroyed in a train derailment earlier this week near Moncks Corner, the state said Wednesday.

Gov. Nikki Haley's emergency declaration in the wake of the collapse of Cypress Gardens Road will help the state get federal money for the project.

S.C. Department of Transportation spokesman Pete Poore said the federal government had given oral approval to fund 100 percent of the construction costs. The state still must complete a formal application process before it can start accepting bids from contractors.

"Typically, it takes 45 days to identify a contractor and get a contract on paper," Poore said. "Contractors are then given incentives to finish early."

Officials had considered putting a temporary structure in place. The DOT has four bridges statewide that can be trucked to a disaster site and reassembled to serve as a solution for traffic during construction.

But that would require crews to build a permanent bridge around the stand-in span, possibly delaying the project's completion, Poore said.

They opted instead to expedite procedures to find a design and a contractor.

Haley signed the declaration Tuesday afternoon that is meant to free up emergency funds from the Federal Highway Administration. The agency's emergency-relief program has about $100 million to spend on such projects annually.

Acting DOT Secretary Christy Hall said Haley's move was a "significant factor" in the state's efforts to quickly obtain that money.

The state pinpointed no timetable for the project's completion, but traffic should be flowing on the road again by the end of October.

"The funding is essentially in place," Poore said. "Now we have to go through the emergency procurement process to identify a contractor."

A portion of the span fell Monday night when four empty cars from a CSX Corp. train derailed and crashed into the concrete posts supporting it.

Nobody on the train was hurt, and a Moncks Corner man whose pickup jumped from one side of the gap to the other also escaped injury.

A CSX spokeswoman, Carla Groleau, said Wednesday that an investigation hadn't yet revealed what caused the derailment. Such probes can take weeks, she said.

Water service for nearby communities also was disrupted. It was restored Tuesday, though residents were asked to boil water. The precaution was lifted Tuesday night, according to an online statement.

State officials said Wednesday that commuters must continue using a 22-mile detour around the site while a replacement bridge is being built.

The ordeal has added to the drive times of people who work at industrial facilities, such as those owned by DuPont and S.C. Electric & Gas, in the Bushy Park area east of the wrecked span.

The DOT has handled problems like this before.

In May 2011, a tanker truck hit the S.C. Highway 150 bridge over Interstate 85 in Cherokee County and blew up. The flames charred the span's underside beyond repair.

That bridge also was two lanes, but it was longer than the one in Berkeley County. Crews replaced it and got traffic flowing again 152 days after the crash.

Reach Andrew Knapp at 937-5414 or twitter.com/offlede.