Charlotte Coffield, a resident of the Lyttonsville neighborhood in Silver Spring, stands on the one-lane Talbot Bridge in September. The span is closed to motor vehicles indefinitely after it failed an inspection. (Sarah L. Voisin/The Washington Post)

A historic Montgomery County bridge that served as a lifeline for African American residents during segregation has been closed indefinitely after it failed a safety inspection, officials said.

Esther Bowring, spokeswoman for the county’s transportation department, said inspectors closed the Talbot Avenue bridge Thursday night after finding that it had deteriorated so much that it was unsafe for motor vehicles. The bridge remains open to pedestrians and cyclists who walk their bicycles.

The county has been exploring ways to move and preserve the one-lane bridge that has spanned railroad tracks in the Lyttonsville neighborhood northwest of downtown Silver Spring since 1918.

The bridge was slated to be torn down and replaced with a longer span as part of building the planned light-rail Purple Line, but longtime Lyttonsville residents began pushing last year to move the smaller bridge so it could be preserved as a historic symbol of segregation. Residents say the bridge provided a vital link between their historically black community and white neighborhoods where they were allowed to work but not live. They said it also connected them to public buses that would take them into the District for dining or movies.

In response to residents’ questions, Barry Fuss, the county’s chief of bridge design, wrote that the “serious disrepair of the bridge” made him recommend that it remain closed until it can be replaced when construction on the 16-mile Purple Line begins.

The Purple Line’s construction, which was scheduled to begin last fall, has been delayed by a federal lawsuit that must be resolved before the project can receive crucial federal funding.

Charlotte Coffield, a third-generation Lyttonsville resident who has advocated for the bridge’s preservation, said she is concerned that with the Purple Line mired in litigation, the community has no firm date for getting a new bridge.

“It’s all hinging on the Purple Line, and we’re not sure if there’s even going to be a Purple Line at this point,” Coffield said. “We don’t really know what this means.”

The wood-and-steel bridge is used by residents traveling between Lyttonsville, neighborhoods to the north and the Capital Beltway.

Bowring said the state will begin building a new bridge within a year of the approval for Purple Line construction.

“The Talbot Avenue bridge will be one of the first projects to move forward,” Bowring said in an email.

Montgomery officials have said that the county-owned bridge was recently rated the most deteriorated in the county. It was inspected every three months, compared with the typical two-year inspection cycle, and had been limited to passenger vehicles under weight restrictions in place since at least 1973.

In February, the Montgomery County Council directed the county to explore moving the bridge, and a parks department official said he would begin seeking a new home for it, perhaps as a footbridge over a trail or stream in a county park.

The bridge also is being considered as part of artwork that would be included at the Purple Line’s Lyttonsville station.