With an eager throng of local residents watching expectantly, workers prepared to hoist the longest free-standing arch span in North America into place above the Mississippi River in Hastings Sunday.

"It is exciting to see the last link being done," said Hastings Mayor Paul Hicks. He said he and hundreds of residents watched through the weekend as tug boats maneuvered the span into place and workers started building a rail system that slid it into place between the piers.

"It changes the landscape and view of our city for the next 100 years," said Hicks, 53, who was born and raised in the river town.

Hydraulic jacks atop the piers began raising the 545-foot twin-arch span and skeletal steel bridge deck to their destination atop concrete piers about 50 feet above the river about 9 p.m. The journey was expected to take between four and six hours, said Tom Villar, project construction manager for the Minnesota Department of Transportation (MnDOT).

River travel and Hwy. 61 traffic on the adjoining old Hastings bridge were expected to resume by Tuesday. Traffic was stopped Saturday morning when tugboats pushed an eight-barge flotilla supporting the 6.6 million-pound structure into place..

Officials said the existing bridge was closed, in part, to prevent dangerous gawker slowdowns. The new bridge, which is supposed to have all four lanes open by December 2013, spans the river on an important route connecting Dakota and Washington Counties.

Expected to last 100 years, the new crossing will replace a steel truss bridge erected in 1952, replacing the historic spiral bridge built in 1895 to carry horses and buggies into downtown Hastings.

The signature terra cotta twin arches, lit at night, will stand 98 feet tall with criss-crossing silver cables anchoring them to the 104-foot wide deck. The four-year-project is about $1 million over its $120 million budget, said MnDOT project manager Steve Kordosky.

The move had been postponed four times. Villar said the delays provided time for crews to make and test welds on beams and railings on the barge platform and to weld support structures for four hydraulic jacks that hauled the span onto the piers.

Villar said the hoisting was supervised by Mammoet, a Netherlands-based specialist in heavy lifting, that deployed some of the same equipment used on bridges in San Francisco Bay.

Getting the span and its skeletal steel beam deck onto the barges was no cakewalk. Four computerized flatbeds on hundreds of semitrailer-truck tires slid under protruding ends of the massive structure. It was rolled about 200 feet from its upstream construction site on Lock and Dam Road, across a temporary causeway onto the barges.

Jim Adams • 952-746-3283