BART has narrowed its options for more secure gates to four, including the “Iron Maiden” turnstiles of the New York subway — thick, prison-style bars that come together like interlocking teeth from floor to ceiling.

Though the barred portals would significantly change the transit system’s open, roomy aesthetic, they found favor with at least one director during a board presentation on Thursday. The agency is considering four options for new gates, which range from a slightly modified version of the current pie wedges, to the highly secure New York model.

“Things aren’t getting any better, so let’s just go with the thing that gives us the most protection,” said Director Debora Allen, who is pressuring BART to crack down on fare evasion, a problem that siphons $25 million a year from the agency revenues.

But the iron gates present complications for a system that’s struggling to move passengers through its entries and exits. They only allow 15 people to move through each minute, half of what the existing gates can manage. The revolving barred doors are also bigger than other concepts, meaning fewer exits could fit in each aisleway. That could spell chaos during rush hour, Board President Bevan Dufty told The Chronicle.

On top of that, the Iron Maiden is not accessible to wheelchairs, which means BART would have to come up with a different innovation for disabled passengers. Allen said she still supports the concept, so long as BART can alter it to allow wheelchairs through and double the rate of entries and exits. Foley suggested trying a “blended” design.

“It would be difficult to achieve,” said Tamar Allen, assistant general manager of operations.

Director Mark Foley also touted the Iron Maiden, saying he thought it might work for some stations. He and Allen also praised two options for plexiglass barriers. One would swing out to let people through; the other would retract into the consoles.

Others, including Director Robert Raburn, recoiled.

“I’m not very enamored of the look and feel of the New York system,” he said.

BART engineers are toiling away at new turnstile designs in a laboratory on the second floor of the agency’s downtown Oakland headquarters. They’ve rolled out one modification already — a “cinched” gate with higher air pressure to prevent cheats from prying the wedges open. Also on the table: a double-decker version with two gates stacked vertically, so that one opens at waist level, the other at chest level.

The stacked gates will appear at Richmond Station this summer, while a “pop-up” barrier concept — plates shaped like shark fins that spring up when the gates close — will debut at Fruitvale. The shark fins provide more security, engineers say, because it’s difficult to vault over them.

Most board directors, including Allen and Foley, encouraged transit officials to continue these tweaks as they assess new designs. The agency has long been dogged by fare evasion and the perception of lawlessness it creates. Many riders associate cheating with the uptick of crime, drug use, and transients on BART, although nobody has proved that connection, Director Janice Li noted.

So far, officials have tackled the problem by hiring inspectors to stand at entry points and cruise through trains, demanding proof of payment. Yet some board directors question the efficacy of that program, and urging BART to “harden” its stations to block cheats.

Modifying the existing gates would be the least expensive option, at an estimated $15 to $20 million. Replacing them with any of the other options could cost as much as $135 million.

BART has yet to identify funds to replace about 600 gates throughout the system, but the lack of money hasn’t deterred the board.

“There’s whole lot of other things we don’t have funding for,” Allen said, alluding to big, necessary infrastructure projects like the second transbay tube. She said the new gates are essential, and the agency would find a way to buy them.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan