The city has halted work on the 34th Street busway project, at least for now, the Federal Highway Administration said Friday, raising new questions about the future of one of the city’s most ambitious transit projects.

In a letter made public Friday, the Federal Highway Administration said it had asked the city’s Department of Transportation to suspend construction on the car-free corridor until officials address federal concerns about how the redesign would affect freight traffic and emergency vehicles, and until city and state Department of Transportation officials meet with the FWHA to discuss the project.

The directive, signed by FHWA Administrator Sean McMaster, follows an earlier letter from the agency in September that said the city’s plans appeared to lack adequate provisions for large commercial trucks that depend on the Midtown route. Federal officials also cited the need to confirm that 34th Street — which forms part of the National Highway System — would continue to meet federal safety and accessibility standards.

In a statement, a spokesperson for the city Department of Transportation said the agency is “confident that the design complies with all applicable federal laws and regulations” and added that the DOT “will work with the federal government to advance this critical project.”

“The vast majority of commuters in Midtown are traveling by transit and they deserve world-class, fast, and reliable buses,” the statement reads. “The redesign for 34th Street mirrors other street designs from across the city and allows for truck, private, and emergency vehicle access on every block.”

The pause marks a setback for city leaders who, in August, celebrated a unanimous City Council vote to advance a sweeping Midtown South rezoning plan that included the 34th Street busway as a central feature. 

Transit advocates hailed the proposal as a long-overdue effort to speed up buses that now crawl across Manhattan at an average of three miles per hour.

Councilmember Erik Bottcher, whose district includes the corridor, had called the busway “a dedicated, car-free route” that would give priority to the tens of thousands of New Yorkers who rely on buses for transportation.

The 34th Street project, stretching from Third to Ninth Avenue, would have allowed only buses, trucks, and certain local drop-offs.

The pause arrives the same week President Donald Trump vowed to revoke federal funding for another of New York’s signature infrastructure and transit efforts: the $16 billion Hudson River Tunnel project, part of the Gateway Program that underpins the entire Northeast Corridor.