The Frederick Douglass Memorial Bridge, one of the District’s busiest commuter gateways, is past its life span. The bridge over the Anacostia River is decaying. Corrosion has eaten holes through the thick steel beams that were installed nearly 70 years ago, and despite a major overhaul in 2007, it continues to deteriorate.

A mammoth construction project to replace the bridge kicked off last month, promising a new bridge in 2021. The project also will remake part of South Capitol Street into a scenic boulevard and improve the Suitland Parkway and Interstate 295 interchanges.

It’s the end of an era for a span that carries 70,000 drivers daily. But the new bridge and redeveloped community will not come without pain.

The new, wider bridge will be built parallel to the old one, near Nationals Park. This will keep most of the construction over the river and limit the impact on traffic on the existing bridge. But travel patterns will shift and lane closures will be needed on nearby roadways, including busy I-295, which itself will undergo major improvements.

“There will be some impacts,” said Delmar Lytle, program manager at the D.C. Transportation Department.

The effects on traffic will be most severe during the non-peak hours, city officials say, while construction noise may be a nuisance for area residents and workers as crews begin to install bridge piles in the next few weeks.

The $441 million project is the first phase of a larger, nearly $1  billion plan to improve the South Capitol Street Corridor, which connects Southeast and Southwest neighborhoods to downtown Washington. It also is the District’s largest transportation construction project in its history.

The project addresses the corridor’s faults, including a transportation infrastructure that “is deteriorating and fails to provide necessary connections to community destinations for pedestrians, bicyclists, transit riders, or motorists,” according to a federal report.

City officials say the project is a major step toward the transformation of the shores of the Anacostia into a world-class waterfront. A modern bridge, they say, will be more in line with the growing development in the area, which has transformed from industrial and military uses into thriving mixed-use communities and employment centers. Growth has peaked around Nationals Park and the Washington Navy Yard at the foot of the bridge.

The new Frederick Douglass Memorial Bridge will be built 100 feet from the existing one; it will have three above-deck arches, two piers that will appear to float in the river and four pedestrian overlooks.

Renderings and video simulations of the bridge show a distinct structure with parallel arches, a multiuse path and pedestrian overlooks. The green areas on each side of the bridge will provide space for community activities.

“This is one of those everlasting projects that we are so glad to bring to its culmination,” D.C. Del. Eleanor Holmes Norton (D) said at the recent groundbreaking. Norton helped secure more than $200 million in federal funding over the past decade for the project.

Signs of trouble with the original bridge were visible decades ago. In March 1986, the District reduced the speed limit on the span and banned most trucks and buses from the heavily used Anacostia River crossing after cracks were detected in steel bars near the middle of the bridge.

Because of its poor condition, the bridge is inspected more frequently than the traditional biannual schedule, city officials say, and because of its age, truck traffic for years has been restricted to specific lanes on both sides of the roadway. It has been deemed structurally deficient for years.

“This bridge got in such decrepit shape,” Norton said, that “it was being eaten alive by rapid corrosion.”

On multiple visits to the foot of the bridge, Norton said, she feared the day would arrive when the city wouldn’t be able to guarantee drivers that it wouldn’t collapse. It never got to that point, and city engineers said there was never danger of it collapsing into the Anacostia, but it was falling apart faster than repairs could be made.

In 2007, the city shut down the bridge to do a major rehabilitation that involved cranking the entire span to a new height.

Even though those repairs addressed the immediate structural deficiencies, the Federal Highway Administration concluded in 2015 that “replacement of the bridge is necessary to address long term structural needs and safety issues.”

Construction on the new bridge itself begins in the next few months. But first, workers will build a temporary trestle bridge over the river that will serve as a construction staging area.

On the I-295 bridge, traffic shifts will occur as crews begin to work on bridge replacement. Some lane closures may occur during nonpeak travel hours.

Along South Capitol Street, just exiting the bridge near Nationals Park, the median between Potomac Avenue and M Street will be replaced with asphalt to create another lane that will be used for future traffic shifts during the construction.

“In the next six weeks or so, things will start to get really loud in here as we start driving the piles themselves for the trestle and the steel piles for the bridge itself,” Lytle said.

Officials say construction noise will be monitored and only expected between 7 a.m. and 7 p.m. (construction will be done from 7 a.m. to 7 p.m. Mondays through Saturdays) to reduce disruptions to nearby residents. And they promise all lanes in the construction zone will remain open during rush-hour commutes for the entire construction period.

The $441 million design-build contract was awarded last year to South Capitol Bridgebuilders, a joint venture of Archer Western Construction and Granite Construction, with AECOM as the lead designer.

The initial work coincides with the commemoration of the bicentennial of Frederick Douglass’s birth. Douglass, who was born into slavery on Maryland’s Eastern Shore in 1818, escaped as a young man and became a leading voice in the abolitionist movement. He moved to Washington in 1872.

“For the District of Columbia, there is no better way to celebrate the 200th birthday of Frederick Douglass than to do what we are about to do,” Norton said. “To begin construction of a bridge named in his honor.”