Christian Jacobs, 6, puts flowers on graves as people visit Arlington National Cemetery in observance of Memorial Day on May 29. Christian’s father, U.S. Marine Corps Sgt. Christopher James Jacobs, died during a training exercise in 2011. (Matt McClain/The Washington Post)

The U.S. Army has broken off negotiations with Arlington County over a long-planned land exchange to aid the expansion of Arlington National Cemetery, after a dispute over what the county would allow on land it would control adjacent to the burial ground.

The Army, which runs the military cemetery, will go forward on its own to turn the site of the former Navy Annex around the Air Force Memorial into space for 40,000 to 60,000 additional graves and inurnments for the cremated remains of deceased veterans, their spouses and dignitaries. The $274 million southward expansion should mean the cemetery will be able to handle demand until about 2050.

The land exchange would have involved Arlington giving the Army control of Southgate Road and Joyce Street, in exchange for getting a compact piece of land nearby that is controlled by the military. The county wanted to use the land it would have acquired for what it called county or public uses — possibly storing its vehicles, building a fire station or creating a museum.

But the Army, which needed control of the roads in order to remove Southgate Road as a barrier to the cemetery, did not want to hand over its land parcel to the Arlington government out of concern that the county would place a heavy-duty maintenance facility there.

Brian Stout, the county’s federal liaison, said that although he assured the Army that plans for a heavy-duty maintenance facility had died with the cancellation of the Columbia Pike streetcar, federal negotiators “couldn’t get comfortable” with the county’s planning process.

The Army did not respond to repeated requests for comment Friday. But the cemetery’s superintendent, Katharine Kelley, said in a statement to Congressional Quarterly Roll Call that “the Army made every reasonable effort to negotiate [the] land exchange . . . [but was] never able to reach an agreement where the Army was comfortable with the county’s several proposed projects for land adjacent to future burial space.”

No negotiations have been held since late last year. Kelley informed county manager Mark Schwartz that it was moving forward without an agreement last week, Stout said.

Under a provision in the fiscal 2017 defense authorization law, quietly passed in December, the cemetery now has the authority to condemn county land that is needed for the expansion.

Schwartz said in a statement that the local government will focus on getting fair compensation for the five acres the cemetery intends to buy. The cemetery will also acquire about seven acres of land owned by the state of Virginia, located between Columbia Pike and I-395.

Lance Allen, president of the Foxcroft Heights Civic Association, which represents the small neighborhood just south of the Navy Annex land, said residents support the cemetery’s expansion, but are worried about traffic, which he described as “dangerous” and “a nightmare.”

Drivers from the heavily used Columbia Pike cut through three small streets — Oak, Ode and Orme — on their way to Southgate Road, which is the southern access route into Joint Base Myer-Henderson Hall, he said.

A new Southgate Road will be realigned by the Army and run parallel to those three small streets. The federal government will also straighten Columbia Pike, with money set aside three years ago.

The roadway realignment and the additional state and local land will increase the size of the cemetery, where more than 400,000 people are buried or interred, from 624 acres to 662 acres.

The cemetery has conducted about 7,000 burials each year since 2004, and it’s been running low on space for years. In 2013, it began a 27-acre expansion in its northwest corner that will provide about 27,000 new grave sites, which is expected to handle demand through the mid-2030s.

An April report from the Secretary of the Army said that, without additional land, the military may have to tighten eligibility requirements in order to control demand enough to allow burials to continue through 2050.