As the 14th Street busway continues to improve mass transit efficiency along a formerly congested stretch of Manhattan, a group of elected officials joined advocates on Wednesday in pushing the city to announce its next target for car-free transit improvements. But so far, Mayor Bill de Blasio isn't making any promises.

The #BetterBuses day of action, organized by Riders Alliance and Transportation Alternatives, centered on the mayor's vow to raise citywide bus speeds by 25 percent before the end of next year. Achieving this ambitious benchmark, advocates say, will involve replicating the 14th Street private car restrictions on several major corridors across the city—and soon.

"We warn you: don’t make us fight another 3 year campaign for #BetterBuses,” said TransAlt Executive Director Danny Harris. "We are hearing about the ‘Miracle on 14th Street,' but we don’t believe in miracles. We believe in hard work."

Potential locations mentioned for a new busway include: 149th Street in the Bronx; Utica Avenue and Flatbush Avenue in Brooklyn; Main Street and Northern Boulevard in Queens; and Richmond Terrace in Staten Island. There's also talk of adding bus priority on the side streets around Rockefeller Center, where the city just implemented temporary pedestrian zones for the holidays.

According to transit officials, bus speeds on 14th Street are up more than 30 percent since the restrictions took effect. Doomsday concerns about spillover congestion—the subject of several project-delaying lawsuits—have not materialized; a preliminary study from the data analysis firm Inrix found that traffic on residential side streets adjacent to the busway has remained largely unaffected.

Citing this successful blueprint, eight city council members who attended the rally said they supported new busways in their districts. They include Transportation Committee Chair Ydanis Rodriguez, as well as Donovan Richards, Antonio Reynoso, Rafael Espinal, Mark Levine, Brad Lander, Stephen Levin, and Ben Kallos.

“Getting New Yorkers out of cars and onto buses will help reduce our greenhouse gas emissions and take a bite out of the unprecedented congestion in our City," said Queens Councilman Costa Constantinides. "We must prioritize bus service in 2020, as we’ve already seen the success in 2019 of focusing on this transit mode.”

Department of Transportation Commissioner Polly Trottenberg has also said she hopes the 18-month pilot program on 14th Street will serve as a "template for other parts of the city.”

Mayor de Blasio, meanwhile, has been reluctant to commit to the future projects.

Speaking on WNYC last month, he acknowledged the busway had "surpassed all expectations," but added that: "I want to have a longer period of examination going into next year because I do want to make sure as we make long term decisions that we know what it means for the surrounding neighborhood and what it means for traffic flow."

"It certainly bodes well for the potential of doing something like this in the future," the mayor continued. "But first I want this pilot to be substantial enough that we really feel we have a strong conclusion."

Last month, the City Council passed legislation that will create 150 miles of dedicated bus lanes on New York City streets. That plan will go into effect in December 2021, a year after the deadline for the mayor's bus improvements, and one month before he leaves office.

Asked if any new busway plans were in the works, a spokesperson for the DOT told Gothamist: "We're consistently looking for ways to reduce New Yorkers' reliance on cars and make it easier to get around the city, which is why we're very happy with initial results of the 14th Street busway. However, transforming any major street is not a decision the City takes lightly. We plan to make decisions on next steps after reviewing more concrete data, including whether to create additional busways."