A Murray construction company will begin assembling Utah's largest "erector set" Thursday - a store-bought, 200-foot highway bridge.

The bridge, to be assembled by Gilbert Western Corp., will serve as the temporary replacement for a concrete structure across the Virgin River between St. George and Hurricane, Washington County. The 50-year-old bridge was damaged New Year's Day when the Quail Creek dike burst and flooded downstream areas.Gilbert Western was the low bidder in the construction project. But officials of the Utah Department of Transportation held off on the contract for a time, while Utah National Guard engineers took a look. State officials said if the Guard could put the bridge together quicker and less expensively, maybe it would do the project.

Guard officers reported that the project was beyond their scope. Also, the Guard is not supposed to compete with private contractors unless it is needed for an emergency.

"They're expected to start Thursday and should take about three weeks," said UDOT spokesman Kim Morris, speaking about the Gilbert Western project.

"The first pieces of the bridge will be arriving Thursday."

The bridge was built by Acrow Manufactures in New York state. It is being shipped to Utah in sections. A company technician will help with the project, he said.

The bridge will be 24 feet wide, allowing two lanes of traffic. It should be in place about 18 months, while the old bridge is repaired.

"We contacted the manufacturer, and they had a 200-foot bridge sitting on the shelf," Morris joked.

"We are purchasing this one, because we will need it down the road." Once the permanent structure is in place, the temporary bridge will be disassembled and stored. It can be used in a shorter length than the full 200 feet.

The Utah Transportation Commission was scheduled to inspect highways damaged by the Quail Creek disaster as part of the group's annual meeting in St. George. On Thursday, commissioners were to tour the damaged highways.

On Friday, the group will meet in the St. George City Council chambers, starting 9 a.m. The public is invited to attend and participate in the commission's discussions.