Brett Young walks near the District’s last remaining streetcar trestle. (Melina Mara/The Washington Post)

After more than five decades, unused and neglected, the District’s last remaining streetcar trestle is crumbling. Sections of the steel supports have rusted away. Wooden ties have fallen. And its structural condition is so poor that the National Park Service closed a trail directly underneath it last August.

Still, preservationists say the state of the 122-year-old bridge, visible from Canal Road in Georgetown, isn’t terminal. A plan to turn it into a pedestrian walkway could breathe new life into it, taking it off the list of the most endangered places in the District and putting it back in service, decades after the trolley line from Georgetown to Glen Echo ceased.

Located north of the Potomac River in Glover-Archbold Park, east of Foxhall Road NW and west of the Georgetown University campus, the trestle was once a critical passage point for the trolley line that transported thousands of people from Georgetown to the amusement park at Glen Echo in Maryland.

The trolley required numerous trestles to carry the tracks over water, along the Potomac. It is the last one standing in the District, officials with the historic preservation office said.

And it shows signs of abandonment and age. The deteriorated concrete columns are covered with graffiti. Significant vegetation has grown in and around it. The steel frame is corroded, and the concrete abutments on each side are full of cracks.

“This bridge is really worthwhile to the region,” said Brett Young, a Palisades resident who has become the trestle’s biggest advocate. “It is a beautiful relic. It is a historical structure worth saving.”

But the Washington Metropolitan Area Transit Authority, which inherited the structure after the trolley closed in 1962, has signaled only a desire to demolish it. Only recently, faced with the difficulties of bulldozing a designated historic structure, has Metro grown more receptive to ceding the property to the city for use as a trail.

Metro spokesman Richard Jordan said the transit agency is in discussions with various agencies to determine the best solution moving forward and is working with the District Department of Transportation (DDOT) “to gauge their interest in taking over responsibility for the bridge and advancing repairs. These discussions are ongoing and no decisions have been made.”

As a more immediate action, Jordan said Metro is exploring adding fencing on the underside of the bridge to facilitate the reopening of the Park Service trail. That work replaces an earlier plan to build a covered walkway, Jordan said, but he declined to specify when the work would be done.

Many trail users, meanwhile, continue to trek under the bridge, bypassing a broken fence and ignoring the Park Service warnings about hazardous conditions. The Park Service has sent numerous letters to Metro, urging the repairs to no avail.

“Until WMATA makes adjustments to create a safe condition we need to keep the trail closed,” Park Service spokeswoman Jenny Anzelmo-Sarles said. “We are still hopeful and eager — hopeful that they will do it and eager for them to do it.”

That would take care of the immediate threat, Young said. But no action toward a complete restoration could be catastrophic. In its fragile state, Young fears that a major storm could cause the bridge to collapse.

The trestle’s deteriorated concrete columns are covered with graffiti. (Melina Mara/The Washington Post)

A 2014 inspection, commissioned by Metro, found it in poor condition and recommended that a restoration program be implemented within three years to address structural concerns, maintain its framing intact and limit further deterioration. Bottom line, the report concluded, the trestle needed fixing — and soon.

After three years, however, Metro has done nothing to stabilize the bridge. That inaction worries preservationists and trail enthusiasts who want to save one of the few remaining early transportation bridges in the city.

In a letter of support for its restoration, the D.C. Preservation League, which listed the bridge as an endangered site, said repurposing the trestle would help preserve a “rare historic resource.”

The trestle is on a route that DDOT has identified as a potential bike and pedestrian trail — an off-road connection between Georgetown and Foxhall Village and potentially beyond to the Palisades area; and a connection to the Capital Crescent Trail that ends in Bethesda and the C&O Canal trail, which extends to Cumberland, Md. It would follow the course left behind by the defunct Glen Echo Trolley line.

“The bridge is a historic resource,” DDOT spokeswoman Maura Danehey said. She said the city is interested in the restoration of the bridge if it could potentially be reused as part of the city’s growing trail network. But before assuming responsibility for the structure, DDOT would first need to conduct a trail feasibility study to determine costs and benefits, Danehey said. The agency plans to launch that study this year.

But there’s no clear timetable when the agencies involved will determine if the restoration is feasible, how to fund such an effort and what would it take to rehabilitate it. A push from Metro to seek demolition isn’t completely off the table.

“We are not aware that ­WMATA has made a final decision on the future of the bridge,” said Chanda Washington, a spokeswoman for the D.C. State Historic Preservation Office, which has been advocating for restoration. “WMATA would need to consult with us . . . before any decision about demolition can be made.”

Metro would not say if the agency had a plan for the 260-foot-long, 20-foot-wide structure or for the nearby parcels of land it owns.

A full restoration could cost upward of $2 million, while an initial stabilization could cost about $715,000, according to the assessment prepared by the consulting firm Structura in 2014.

Because the trestle is listed on the National Register of Historic Places and the D.C. Inventory of Historic Sites as a contributing element of the Glover-Archbold Historic District, it may be eligible for federal funds, officials say.

“My biggest worry is that WMATA has no plans for the bridge and they are just waiting for the bridge to fall down,” said Young, 45, who became intrigued by the structure three years ago during a post-knee-surgery workout. The trestle became a frequent stop in his routine walks and bike rides, and he learned to see it as more than a relic, he said. The thought that it could still have utility compelled him to embark on a campaign to save it.

Now time is of the essence, he said.

“They have had enough time to do nothing and it’s time for them to make a decision and act on it,” he said. “You fix it and it can last another 120 years.”