Mayor Zohran Mamdani said on Wednesday that New York City would move forward with a project to improve bus speeds on a busy thoroughfare in the Bronx, reviving an initiative that was put on hold after objections to similar plans from the Trump administration.

The project will bring a dedicated “busway” — which is reserved for buses, emergency vehicles and trucks during peak travel times — to a stretch of Tremont Avenue, a change that city officials said would shorten commutes for 39,000 bus riders each day.

The mayor’s office also said that it would gather input in Brooklyn for plans to improve bus service there, on 13 routes that carry roughly 150,000 daily riders on Flatbush Avenue, Utica Avenue and Church Avenue.

“We want New Yorkers to have faith in our outreach, and that starts with actually delivering on projects promised years ago, like on Tremont Avenue, where riders deal with unreliable, overpacked buses every day,” Mike Flynn, the city’s transportation commissioner, said in a statement.

The announcements are the latest step in the mayor’s push to fulfill a campaign promise to improve bus service. New York has one of the slowest bus fleets in the nation, with an average speed of eight miles per hour. The announcement comes one week after Mr. Mamdani and Gov. Kathy Hochul announced a plan to make buses up to six minutes faster on routes across the city through street redesigns, expanded traffic enforcement and other changes.

In a statement, Mr. Mamdani said his administration was “building streets that move people instead of sticking them in gridlock.”