A later proposal by the nonprofit Friends of the Brooklyn Queens Connector, made public in January 2016, found backing from Mayor Bill de Blasio.

There has been criticism of the project, namely that its completion date of mid-2020s might make it obsolete; that it did not have a clear source for funding; and that it was a poor substitute for subway service.

[3] In the 1990s, the BHRA received permission from New York City's government to develop a streetcar line running from Beard Street to Borough Hall.

The association's president Robert Diamond collected disused PCC streetcars that had been used in Boston and Buffalo for potential use on the new line.

[5] The study concluded that, due to a number of factors such as high costs, low ridership, and physical constraints like narrow streets, a streetcar line would not be an appropriate transit solution for the area.

[5][6] By June 2013, Diamond had partnered with John Quadrozzi of Gowanus Bay Terminal (a concrete firm), and the Gowanus Canal Community Development Corporation in an effort to revive the project, which he now envisioned running partly underground through the Cobble Hill Tunnel, a former Long Island Rail Road tunnel under Atlantic Avenue.

The streetcar would cross Newtown Creek into Greenpoint, then pass through Williamsburg and the Brooklyn Navy Yard using one-way streets close to the waterfront.

It would turn onto Park Avenue, run to Navy Street, then through Farragut Houses, Vinegar Hill, and Dumbo.

[8] One other option, Select Bus Service, was estimated to cost $1 billion to implement, and was not chosen since it would not raise property values as a streetcar would.

[16] City officials said that several years of additional study and review would precede groundbreaking, planned for 2019, with service beginning around 2024.

[12] Mayor de Blasio's office commissioned a study toward researching the projected effects of the streetcar.

[11] Under the slightly revised plan released by the city, the route would travel 16 miles (26 km) with 30 wheelchair-accessible stops, with an increased construction cost of $2.5 billion.

[11][15] There would be sixty vehicles, costing $5 million total,[11] that would travel at 11.3 miles per hour (18.2 km/h), and would be separated from vehicular traffic for 70% of the route.

[11] Electrification is proposed to be from hydrogen fuel cells within the streetcars themselves, as opposed to from overhead lines or from embedded rails.

[11][15][21] An additional motivation for the line has been the tremendous growth in Brooklyn and Queens waterfront areas since the early 2000s.

[22] In May 2016, Friends of the Brooklyn Queens Connector appointed its first executive director, Ya-Ting Liu, to oversee route operations and design.

The $100,000 prototype, a Citadis low-floor streetcar created by Alstom, was displayed at the Brooklyn Navy Yard.

[36][38] Additionally, if the BQX's construction were to proceed, the project would interfere with the renovation of the Brooklyn Heights Promenade section of the Brooklyn-Queens Expressway, which would occur during roughly the same time frame.

This was supposedly because of cost constraints, since it was projected that the stops in Sunset Park and Dumbo would not have enough ridership to justify building the streetcar there.

[42][43] The NYCEDC announced in February 2019 that it had awarded a contract to create an environmental impact statement for the BQX.

[46] Afterward, the city would perform a comprehensive Uniform Land Use Review Procedure zoning plan (ULURP) for the areas along the BQX.

[50] A different rail line between Brooklyn and Queens, the Interborough Express, was announced in 2022; this route would use the Bay Ridge Branch and Fremont Secondary, rather than running along the waterfront as the BQX did.

These options would have then traveled down either Franklin Street, Manhattan Avenue (over the Crosstown subway line), or McGuinness Boulevard, respectively.

While it was planned to connect to 17 subway stations, it would have been far from the BMT Canarsie Line (L train) at Bedford Avenue.

[58] In a May 2016 editorial in the New York Daily News, Princeton University professor Steven Strauss stated that he was concerned that autonomous vehicles might make the project obsolete when it was completed.

Instead, Strauss recommended that the city engage in a wider Request for Expressions of Interest Process to look at other potential alternatives.