There’s a streetcar being planned through Red Hook and many residents would like to know why.

About 50 or so New Yorkers filtered into the Red Hook Recreation Center Thursday evening to get involved with the early development process of the Brooklyn Queens Connector, Mayor Bill de Blasio’s proposed waterfront streetcar plan to connect Astoria, Queens, to Sunset Park, Brooklyn.

Like the last meeting in Astoria, attendees were hung up on the project’s cost, $2.5 billion, and how the streetcar would be married to the existing streetscape.

Representatives from the Department of Transportation and the New York City Economic Development Corporation came with maps and stickers to help document that feedback.

Some wondered if a investment in bus infrastructure could have a greater impact.

“As of right now I don’t support the BQX,” said Adrienne McIlvaine, 34, a freelance writer, and Red Hook homeowner who was in attendance with her partner William Matelski. “I think express buses into Manhattan or downtown Brooklyn would be more beneficial.”

Matelski, an audio engineer, was concerned about their property tax rates and the resiliency of a streetcar.

“So much of this neighborhood is in a flood-risk zone,” he said. “That brings into question the long-term viability of this project.”

Lydon Sleeper, EDC senior vice president for government and community relations, noted that resiliency is a key principle of the project.

“Surface transportation is a resilient method of transportation,” he said. “Part of the lessons learned from Sandy is incorporating resiliency in all our planning and work that we do moving forward.”

Sister Rosana Cervone, from Red Hook’s Visitation of the Blessed Virgin Mary church, said her main concern was increased community displacement that might come along with the streetcar.

“I think it’s a great idea, but they must be careful about gentrification and pushing people out of the neighborhood,” said Cervone, 64, who originally moved to Brooklyn from Italy in 1968.

Local Councilman Carlos Menchaca addressed the crowd before the meeting. He said he’s all for bringing more transit options to Red Hook, but before he can back the streetcar he must make sure the community’s input is heard and reflected in the design.

There will be plenty of time for that. At this stage, the city has yet to finalize details about the exact route or where the BQX will be given a dedicated right of way; whether there will be fare integration with the MTA, or what power source will carry the streetcar.

Preliminary estimates from the city suggest that the BQX would serve 45,000 to 50,000 riders daily, or 15 million each year. Streetcars would travel at about 12 miles per hour, making stops every half mile. The city points out that the route would connect 13 NYCHA developments where more than 40,000 people live.

But Steve Fontas, a Carroll Gardens business owner, questioned the mayor’s claim that the BQX would be serving transit-starved neighborhoods. He said he’d rather see mass transit serving lower income neighborhoods of Brooklyn, like East New York, Brownsville or Flatbush.

“I have a lot of workers who live in those neighborhoods and struggle to get to work,” Fantas said.