MOUNT PLEASANT — U.S. Highway 17 will close for five nights starting Tuesday night so crews can hoist into place two massive beams to help support the new Interstate 526 overpass to Hungryneck Boulevard.

The road closure starts at 11:30 p.m. on Tuesday, Wednesday and Thursday and lasts until 5 a.m. the following mornings. It continues on Friday and Saturday, when the highway will shut down at 10:30 p.m.. It will re-open to traffic at 7:30 a.m. Saturday and 9 a.m. Sunday, officials said.

Two giant red cranes will hoist the 225-foot-long, 50-ton curved beams one-at-a-time and move them ever-so-slowly into place next to four beams that were placed last week, when the road was also closed overnight for most of the week.

Although lifting that much steel and bolting it into place sounds dramatic, there’s really not much for curious nightowls to see while the work is happening because of the pace at which it proceeds, said Ed Barbee, the town road construction public information officer.

“If you like to watch grass grow. It’s a very slow process,” Barbee said.

To get any kinks out of the process, the assembly of the beams has already happened once in a dry-run at Augusta Steel, said Horace Petit, town field engineer.

“Just like Legos,” he quipped. The last of the seven beams will be placed next week, when U.S. 17 is again expected to close at Hungryneck Boulevard on the same Tuesday through Saturday schedule, officials said.

It has not yet been decided whether more overnight closings of the highway at that location will be required when concrete is poured to form the bridge deck, Barbee said.

When finished, the overpass will mean a quicker route to the Isle of Palms Connector and the beach, Barbee said.

The work is part of a massive road construction project from the Arthur Ravenel Jr. Bridge for more than five miles to Darrell Creek Trail. The project costing more than $100 million is mostly funded through the county Roadwise program. Other funds are from the State Infrastructure Bank and the town.

Construction of the $26.7 million I-526/Hungryneck improvements is scheduled for completion next January. The $68 million county Roadwise program widening of Johnnie Dodds Boulevard from Ravenel Bridge for three miles to just south of I-526/Hungryneck is scheduled for completion in December. The four lane road will become six lanes.

In November, construction is expected to be finished for widening U.S. 17 from IOP Connector to Darrell Creek Trail. The $29 million project is funded by the town, Charleston County and the Federal Highway Administration. The four lane road will become six lanes.