Riders take part in the Rolling Thunder First Amendment Demonstration motorcycle run on Memorial Day, 2015. (Jonathan Ernst/Reuters)

The iconic 1930s-era Memorial Bridge that leads from the entrance of Arlington National Cemetery to the Lincoln Memorial is so badly corroded that two lanes must be partially shut down for six to nine months starting with Friday’s morning rush hour, federal officials said Thursday.

In addition, a 10-ton load limit across the entire length of the bridge essentially eliminates most bus traffic on the granite-faced, arching landmark for even longer, pending a much-needed rehab of the whole bridge, officials said. The prohibition begins Friday, but with an “education period” without ticketing for a couple of weeks to give Metro and tour bus operators time to find detours, according to the National Park Service.

Although tens of thousands of U.S. bridges have been deemed “structurally deficient,” the functional mess and potent symbolism of a crumbling Memorial Bridge needing emergency repairs had the Washington region’s congressional representatives fuming.

Sen. Tim Kaine (D-Va.) warned of “unbearable congestion” for the more than 60,000 drivers who cross the Potomac between Virginia and the District daily. Sen. Mark Warner (D-Va.) called it “not just embarrassing – it’s outrageous.”

The Memorial Bridge was one of 14 “structurally deficient” bridges in the nation’s capital, according to federal data released in January and compiled by the American Road and Transportation Builders Association. Nationally, 61,064 spans get that broad designation, which indicates “major deterioration, cracks, or other deficiencies in their decks, structure, or foundations,” according to the U.S. Department of Transportation. The label is not meant to indicate imminent danger, which bridge engineers said would result in a bridge being shut down.

Arlington Memorial Bridge repair begins

Del. Eleanor Holmes Norton (D-D.C.) said the price tag of up to $250 million for repairing the bridge is more than the Park Service receives for transportation projects nationwide, pointing to a yawning gap in infrastructure funding.

One curbside lane on the bridge, headed outbound to Virginia, was shut earlier this month to make way for inspectors, who discovered the more profound problems that prompted the latest restrictions.

As of Friday, both curbside lanes will be closed along the old drawbridge section of the bridge, taking two of six lanes partially out of commission. Four-foot strips of adjoining sidewalk will also be shut in both directions. Federal Highway Administration engineers found that steel “secondary” support beams were corroding more quickly than expected and “no longer meet load-bearing standards,” according to the Park Service.

Scans of the concrete bridge deck also helped uncover “significant deterioration,” leading to the new 10-ton weight limit that will block approximately 150 buses that traverse the span daily, according to Park Service spokesman Wayne Campbell.

“The load restrictions will be indefinite, until there is a rehabilitation or repair of the full bridge,” Campbell said. Those restrictions are on the entire 2,100-foot span, not just on the drawbridge section where the lane closures will occur. “Passenger vehicles are fully safe to go across the bridge, as long as they stay in the open lanes and are within the load limit.”

Warner blamed his congressional colleagues for failing to fund fixes not only for a key entrance to the nation’s capital but also for other bridges, highways and ports. Until national leaders “get serious” about paying for those improvements, “commuters will be stuck sitting in even more traffic – and crumbling and inefficient infrastructure will remain a serious drag on our economic growth,” Warner said in a statement.

The Arlington Memorial Bridge was dedicated in 1932, and the corroding drawbridge was last opened in 1961, the Park Service said. “Symbolically, the bridge was designed to show the strength of a united nation by joining a memorial on the north side of the Potomac River . . . with one on the south,” according to the Park Service, and the bridge’s eagle sculptures, bas-relief bison and artistic oak leaves are meant to “invoke national strength and unity.”