A prominent group of New York planners will on Tuesday argue the city should try to reduce demand for the Brooklyn-Queens Expressway before moving forward with controversial repair plans that involve temporarily replacing the Brooklyn Promenade with a six-lane highway.

The Regional Plan Association will release a report arguing that traffic mitigation measures, including the state’s recently approved congestion pricing plan, could reduce demand to such a degree that the city might be able to get away with building a smaller temporary highway while reconstruction is ongoing, and a smaller permanent highway moving forward.

“Reduced traffic demand would open up different design alternatives than what they’re currently looking at,” said Kate Slevin, a senior vice president at the Regional Plan Association.

Last September, New York City Transportation Commissioner Polly Trottenberg told reporters that the de Blasio administration was in the unenviable position of having to move forward with a more-than-$3 billion highway reconstruction project in one of the city’s wealthiest neighborhoods. The BQE triple cantilever, whose top level supports the Brooklyn Promenade, was deteriorating to the point where, absent substantial repairs, the city would have to ban trucks in 2026. The structure might no longer be strong enough to support cars by 2036.

Even worse, the city’s preferred option for repairing the triple cantilever would involve running a six-lane highway along its upper tier —the Brooklyn Promenade — so workers could repair the levels below. Trottenberg compared the project to Boston’s notorious “Big Dig.”

The Brooklyn community responded with predictable levels of outrage. Neighbors pooled their resources. Lobbyists were hired. PR consultants, too. Some residents began tossing out fanciful-seeming reconstruction ideas of their own.

A Better Way, a Brooklyn Heights organization that formed after the city announced its reconstruction plans, hired the Regional Plan Association to perform the analysis it is releasing today.

A Better Way’s intent was not to come up with construction alternatives, so much as to create the space for others to do so, according to Hilary Jager, a spokesperson for the group.

“We’re community members, we’re not architects — well some of us are architects,” she said, in an interview last week. “But it demands a level of expertise and depth. And we thought that by trying to encourage the experts and other parties to bring ideas forward, we would have the best possible ideas.”

In addition to congestion pricing, the city should, the analysis argues, consider high-occupancy vehicle restrictions on the BQE during peak travel periods and similar restrictions on the East River bridges that connect to the BQE. Further, the report recommends looking at reinstating two-way tolls on the Verrazzano Bridge, which also sends cars onto the BQE.

“[The] findings strongly suggest that these policies, either individually or in combination, could reduce traffic enough to accommodate remaining demand with fewer lanes than the existing six-lane highway,” the report reads.

Even if further analysis does not bear that out, the city might consider rebuilding the BQE with fewer lanes anyway, the RPA argues. (Comptroller Scott Stringer advanced a similar argument in March.)

After all, when, citing safety concerns, the transportation department closed the Williamsburg Bridge to traffic for more than a month in 1988, “The average daily traffic of approximately 107,000 vehicles was absorbed into the system,” the report notes. The BQE carries about 150,000 vehicles a day.

Similarly, in 1973, a partial collapse of the West Side Highway necessitated prolonged repairs, and a transformation of the highway into what the report describes as a de facto boulevard.

“We have not been able to obtain specific traffic impacts due to the closure,” the report reads. “But by one account 53% of the traffic formerly carried on the highway simply disappeared.”

Further, the report recommends the city create an independent advisory board of architects and transportation experts and that the state work with the city on the project. (It used to be a state project, before the state abdicated its role in 2011).

Alana Morales, a spokesperson for the Department of Transportation, said the city was reviewing the plan.

“DOT saw the preliminary report and looks forward to reviewing and taking a deeper look at the final product,” she said in a statement. “We are undertaking a thorough review process, accompanied by substantial community and expert engagement, that will look at a range of options for this critical transportation corridor, including the ones proposed in the RPA/A Better Way report.”