Construction of a 160-foot steel Band-Aid for the Skagit River Bridge began Tuesday while a meticulous examination of the damaged section continued above and below the water.

Acrow Bridge is building the temporary span in pieces on a closed stretch of I-5 to be rolled into place for final assembly once the National Transportation Safety Board completes its work and demolition crews clear away the remains of the collapsed segment.

The Department of Transportation didn’t say how much the temporary bridge costs, but said it would be part of the $15 million emergency contract awarded to Atkinson Construction in Renton to clear the wreckage and rebuild the bridge.

Gov. Jay Inslee is pushing for a mid-June reopening, and state transportation officials say the timeline is doable but caution against chiseling in a date.

There’s no plan to hurry the federal authorities or rush the cleanup. Plus, state bridge experts must still examine the steel and concrete piers that supported the collapsed span to be sure they can be used for the replacement.

“We do have some challenges ahead of us,” said Travis Phelps of the DOT. “We are going to do our best to meet that timeline. We want to be sure it is done right and safe. This work ain’t easy.”

Tuesday brought word that Acrow Bridge, a 62-year-old New Jersey bridge-building firm, will construct the temporary four-lane segment to replace the section that crumbled into the Skagit River on May 23.

When completed, it will consist of two prefabricated steel bridges installed side by side. Each piece will be 160 feet long and 24 feet wide, which is wide enough to support two lanes of traffic. The road will have an asphalt overlay or a factory-applied aggregate anti-skid finish, according to a company spokeswoman.

When the bridge reopens, just about every vehicle, commercial truck and tractor-trailer allowed to travel on it before the incident will be able to travel on it again, Phelps said.

Transportation officials will set a maximum vehicle weight to be allowed on the temporary bridge. Overweight vehicles, referred to as super loads, are not going to be permitted, he said.

Some trucks with oversized loads, like the one that struck the bridge and caused the collapse, could use the bridge if they do not exceed the weight limit, he said. They will need to comply with existing rules, such as use of a pilot car with a height rod, he said.

Speed will be reduced on the bridge because the lanes will be narrower, there will be little or no shoulder and some type of barrier will be in place dividing the northbound and southbound lanes, Phelps said.

Acrow Bridge, which has an office in Camas, Wash., specializes in pre-fabricated modular steel bridges. It has built similar bridges to replace ones damaged in hurricanes Katrina, Irene and Sandy, according to the company.

Meanwhile Tuesday, Inslee moved to assist retailers who’ve seen business plummet since the span tumbled into the river, fracturing one of the major trade and travel corridors on the West Coast.

He approved using $150,000 of the state’s Economic Development Strategic Reserve Account to support economic activity in Skagit County and surrounding areas.

None of the money can go directly to a business, according to the governor’s office. The Department of Commerce will use the money for a media campaign focused on informing the public that the region’s businesses and attractions are open and how best to get there. Island, Whatcom and San Juan counties also will be involved.

The Washington State Patrol has beefed up its presence along the detour routes due to complaints of semi-trucks and cars with trailers running red lights and blocking intersections when traffic signals turn red. Both are infractions and can result in a $124 ticket, according to the state patrol.

“We understand the detours are an inconvenience for motorists but we want to make the routes as safe as possible. Motorists need to pack their patience while these detours are in place,” Trooper Mark Francis said in a statement issued Tuesday.

Jerry Cornfield: 360-352-8623; jcornfield@heraldnet.com.