A reborn Market Street, purged of private cars at the end of the month, may include futuristic glass canopies over each BART station entrance.

The transit agency built two such fixtures at Powell and Civic Center stations in 2018, and erected a third at 19th Street in downtown Oakland. The refurbished main entryway in downtown Berkeley also features a big glass-skinned archway.

On Thursday, the board is set to approve a $64.5 million contract for 19 more, covering every stairwell on San Francisco’s main thoroughfare. BART staff hope to eventually find funding for another three canopies.

The money would come from voter-approved bonds for BART and Muni, which share the downtown stations.

At more than $3 million apiece, each canopy will cost about as much as a swank house in Noe Valley. But spokesman Jim Allison notes that these ornamental structures aren’t easy to build. They require complex underground construction, utility work and engineering. Once completed, they’ll be outfitted with security cameras and real-time train arrival displays.

The canopies serve an obvious practical purpose. They shield the escalators and stairwells from rain and blowing debris, and provide a barrier against carelessly tossed cigarettes or hypodermic needles. They’ll protect a $100 million investment the BART board approved last year to repair 41 battered escalators at Embarcadero, Montgomery, Powell and Civic Center stations.

BART set aside $12.7 million for elevator and escalator maintenance this year alone.

“Some stuff is just not good to throw on a working piece of machinery like an escalator,” said BART Board Director Bevan Dufty, addressing reporters Tuesday outside the canopied entrance at Powell Street Station as streetcars and delivery trucks clattered by.

Cutting back escalator maintenance would save BART money in the long run, said Supervisor Matt Haney, whose district includes all the Market Street stations. He voted to allocate up to $45 million as Muni’s contribution to the project.

Debris and inclement weather aren’t the only things plaguing the rail system. BART also struggles to deal with transients who take shelter inside and around the stations. Staff say this project will help, because the canopies come with motorized gates to close the stairways overnight when trains aren’t running.

A station agent demonstrated that feature Tuesday, using a key to switch on the motor, which caused the grille to roll down with all the slow-motion grandeur of a garage door.

“They close off the area when BART isn’t in service, and protect from ‘unwanted behaviors,’” Allison said, highlighting the extra layer of security. For the past several years, rail system officials struggled to chase out drug users and others seeking refuge in BART’s core San Francisco stations.

With the new glass-shrouded gates, transients could no longer sleep in the stairwells. That’s a significant improvement for station agents who arrive to unlock the entrances at 4:30 a.m., Dufty said.

Since 2018 the canopies have provided tangible benefits at 19th Street in Oakland, where officials saw escalator outages reduced by 30%.

In San Francisco, the structures would help create a safer and more stylish atmosphere as Market Street transforms from a busy transit artery into a 21st century civic spine. While officials tout the engineering beauty of the new entryways, riders say they’d welcome anything that blocks out drug use and keeps the escalators from breaking down.

“I don’t know about canopies, but my BART experience would be significantly improved by functioning escalators,” said Hayes Valley resident Ian Armstrong, who stood outside the UN Plaza entrance at Civic Center on Tuesday afternoon. It now lacks any form of shelter, which dismays some riders. People have been known to smoke hard drugs at the base of the stairwell and toss bottles over a side railing.

San Francisco resident Nataly Kauil acknowledged she’d feel safer with a glass and steel buffer.

“Especially with all those drug dealers around the corner,” she said, gesturing to a crowd loitering in the plaza nearby.

If the board approves the canopy contract, construction will begin this fall. Officials expect to finish the project by 2026.

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