Seasonal work on the Bong Bridge began Monday, as workers started to set the stage for construction that will begin in earnest next month.

For now, there is a single lane closed in either direction. Beginning April 13, eastbound lanes and one westbound lane will be closed until Nov. 2.

The work - concrete deck mill and overlay, painting the truss, structural joint replacements and lighting upgrades - is the resumption of a two-year Wisconsin Department of Transportation project that began last year. The $11 million project will also include the completion of an eastbound roundabout that will funnel traffic onto Belknap Street or Garfield Avenue.

The bridge's lone sidewalk - on the eastbound side - closed Monday. WisDOT is encouraging pedestrians and bicyclists to use the Duluth Transit Authority bus system, since the primary detour route over the Blatnik Bridge - roughly 2.5 miles north - does not have sidewalks.

"We're in a difficult spot," said Matt Dickenson, WisDOT project manager. "A good chunk of sidewalk has to be cut off and recast due to some pretty significant deterioration on the edge of the sidewalk. We have to repour a lot of it."

Dickenson believes the DTA, with its bike racks on buses, will be able to accommodate the bridges' usual foot and pedal traffic.

A study last May using traffic camera recorders revealed a glimpse at the bridge's non-automobile users. Over three days, 16 pedestrians and 51 bicyclists used the bridge, with as many as 33 bicyclists in one day and seven pedestrians.

"We're fortunate to have a DTA system where buses run every hour," Dickenson said.

The single westbound lane that will be closed will be used for materials and equipment delivery.

Not originally included in the plan for revamping the bridge, the roundabout was added at the suggestion of a participant at one of the original Bong Bridge public meetings, Wisconsin Public Radio reported in 2012. The roundabout itself costs between $400,000 and $600,000.

About 15,000 vehicles use the Bong each day, WisDOT has said. The Blatnik carries 20,000 to 30,000 a day.

When it was built between 1979 and 1984, the Bong Bridge cost $70 million - an amount that inflation has more than doubled.

The bridge, which carries U.S. Highway 2 between Minnesota and Wisconsin, was designed to last at least 75 years, WisDOT has said. The ongoing work is the first major maintenance project on the bridge since it opened to traffic on Oct. 25, 1984.