D.C. United is trying to get zoning approval for its planned 19,000-seat stadium in Southwest D.C. (DCU/Populous)

Members of the D.C. Zoning Commission peppered D.C. United officials with questions about the team’s stadium plans Monday, raising concerns about transportation, environmental impact and design that could effect the team’s targeted start date for construction.

The city’s zoning review body is the last major obstacle for the city’s Major League Soccer team, which has said it needs a January or February groundbreaking to be able to cut the ribbon on a finished 19,000-seat stadium by June 2018.

As it is, a summer 2018 move-in date put them about a dozen matches into their season.

United’s stadium would be the league’s most expensive stadium ever, built on the smallest site in the league. The commission’s questions largely focused on how the team would accommodate large crowds at the site, located about a 15-minute walk from the nearest Metro station at Navy Yard.

The stadium plan does not include parking on-site; even the players will have to leave their cars with a valet. The team’s transportation expert said the demand for parking spaces will be in the 3,000 to 4,000 range, but that supply at nearby garages exceeds that estimated demand.

The team has written agreements with a few of those garages that they will be available for staff and fans, though many of the available spaces are in lots and garages closer to the Metro station than the new stadium site.

“You are going to drive people’s transportation behavior depending on how you design this,” said board member Peter Shapiro.

Advisory neighborhood commissioners in the neighborhood around Buzzard Point in Southwest called for the panel to reject the plan, citing concerns about managing traffic.

“The ANC continues to withhold its approval until a revised [plan] adequately addresses continued concerns stated in this report that specifically address issues of transportation, environment and lack of attention to the needs of the adjacent neighborhoods,” ANC 6D Chairman Andy Litsky wrote in a Nov. 21 letter.

Prior to the hearing the team cleared a major hurdle: the opposition of neighboring property owner Akridge, a D.C. developer. An attorney for Akridge sent a letter to the commission Monday before the hearing to withdraw its October request to speak against the plans.

The team offered to commit to not holding matches on the same day as Washington Nationals home games to allay concerns about the impact on the transit system and the neighborhoods streets. The Nationals have not made any similar commitments.

A permanent bike valet that wraps around a corner of the stadium may also help with crowds and reduce car trips. The plan is for 400 bike racks and the team will provide additional corrals for both privately-owned bikes and bike-sharing bikes as needed.

A spokeswoman for the team, Lindsay Simpson, said that so far the team’s timeline remained intact. “We don’t anticipate any delays in construction or our timeline at this time,” she said in a statement.

Monday’s nearly five-hour meeting made the prospects of a speedy approval before year’s end unlikely. Commissioners scheduled a continuation of the hearing for Dec. 14 at 6:30 p.m.

“There has never been a transformative project in the District of Columbia that went by quietly,” said Brian Kenner, D.C. deputy mayor for planning and economic development.