With repairs as the focus, Multnomah County is systematically working its way through Willamette River bridges in downtown Portland, bringing the crossings up to speed in terms of maintenance and operations.

Next on the list: the Burnside Bridge.

The up to $22 million project to repair the road surface, bridge structure and electrical/mechanical systems starts on Jan. 5 with the extent of the work potentially lasting through 2019. The bulk of the two-year effort puts a focus on replacing cracking and crumbling concrete—including on piers and concrete columns—on the 1926-opened bridge, upgrading the electrical system for raising the bridge and fixing rusting on the steel framework.

During construction, the 2,200-ft-long bridge will close two lanes, reducing the number of lanes to one westbound and two eastbound. The county plans to keep paths open for bicyclists and pedestrians.

A more detailed list of the work, which the county expects to help the bridge last another 20 years, includes spot repairs to pavement, sidewalks, overhangs and railings; replacing expansion joints, which allow bridge sections to expand and contract with temperature change; sign painting; repairing cracks in piers; repairing the concrete columns that hold up the bridge, including the beams and girders; painting steel trusses; repairing the inside of the internal steel towers that connect to the piers; replacing the drawbridge span locks and motor; and upgrading the power supply and drawbridge controls.

HDR Inc. designed the fixes and Hamilton Construction will serve as the general contractor.

The Burnside Bridge is located on one of the longest and busiest streets in the Portland area, serving as a connection between downtown Portland, Beaverton to the west and Gresham to the east while hosting about 40,000 vehicles and 2,000 pedestrians and bicyclists each day.

The bridge was the first Willamette River bridge in Portland designed with the help of an architect, resulting in distinctive Italian Renaissance towers. The drawbridge opening mechanism was designed by Joseph Strauss 11 years before his Golden Gate Bridge opened. The Burnside Bridge includes two 268-ft steel deck truss side spans and a 252-ft double-leaf Strauss trunnion bascule draw span. Two concrete counterweights weighing 1,900 tons each can lower to open the two lift-span leafs.

Originally designed with six lanes of traffic and sidewalks at 86 ft in width, a 1995 change converted one lane of traffic into two bike lanes.

Follow Tim Newcomb on Twitter at @tdnewcomb