Repairs to the crane-damaged Sunshine Bridge should be completed in early February, but to increase the chance that all four lanes will reopen by then, highway workers will need to close the entire span to replace a crucial brace beneath the road deck.

“Crews have been working hard and we’ve made significant progress, but we can’t rush the remaining repairs,” said Shawn D. Wilson, secretary of the state Department of Transportation and Development.

A barge-mounted crane struck the St. James Parish bridge Oct. 12, damaging a key support beam and other critical parts of the 1½-mile-long structure, which connects the eastern and western portions of Ascension Parish. DOTD deemed the bridge unsafe for traffic and shuttered it until temporary repairs let crews open one lane in each direction Dec. 1.

The permanent repair will force workers to close the Sunshine Bridge during the weekend of Jan. 19-20.

The DOTD’s timetable is “very weather dependent,” the agency said. Workers operate on open-air platforms underneath the structure that are more than 100 feet above the surface of the Mississippi River.

Can't see video below? Click here.

And even when the emergency repairs are finished, drivers won’t be finished with some lane closures on the bridge during the coming months, as workers perform maintenance scheduled before the barge crash.

DOTD officials plan to repair the superstructure and substructure of the approach spans to the metal cantilever truss bridge. The approach spans are the elevated sections of bridge that cross over land and are on either side of the metal cage-like structure that spans the river.

Wilson said that the previously planned maintenance work on the 54-year-old span "will make this bridge safer and will extend its life.”

The project was put out for bid in 2017 and had been scheduled to have some periodic lane closures starting this month before the barge crash happened. DOTD officials said the maintenance work is expected to last until August.

The October crash disrupted lives and business activities for the thousands of people who had used the span daily and who instead had to take extended detours or wait for ferries.

During the Jan. 19-20 closure, workers will install an additional replacement support beam under the road deck, so-called diagonal bracing, which has already been fabricated and is being painted and prepared for installation.

DOTD officials said in a statement that the weekend closure later this month is necessary for the safety of drivers and the workers on the bridge.

The damaged diagonal bracing was visible in early photographs that state highway officials took after the crash. The images showed the metal support structure under bridge deck, with X-shaped beams — the diagonals — that had been mangled.

A crane was mounted on a barge being pushed upriver when it hit the bottom of the bridge. The barge became stuck under the bridge until the height that the barge sat in the water could be lowered enough to move the vessel.

Since the bridge was partially reopened last month, crews have been working below the bridge deck, repairing cracked welds, replacing damaged bolts and preparing for replacement of the diagonal bracing, DOTD officials said.

In addition to the coming installation of the bracing, workers also must replace gusset plates, thick pieces of steel that connect structural members to one another.

Follow David J. Mitchell on Twitter, @NewsieDave.