BART officials have a new strategy to entice people onto the rail system’s flagging San Francisco airport line: priority for BART riders at the airport security gates.

At Thursday’s meeting the board will vote on whether to approve new technology to scan Clipper cards and BART smartphone apps, so that riders who show proof of payment can stand in a separate line that is presumably shorter and faster. If the airport agrees, the perk could take effect as soon as next year.

The idea? Boost a segment of the rail system that has stumbled in recent years, a slump that officials largely blame on competition from Uber and Lyft.

“The data shows we started to see the decline in 2015, after years of growth,” said BART spokesman Jim Allison. “That’s when the airport legitimized Uber and Lyft drop-off,” rather than restricting the ride-hail companies, he said.

BART entries and exits at San Francisco International Airport decreased 16 percent from September 2015 to September of this year — from 14,974 riders each weekday to 12,615. In the meantime, more people are getting to the airport in cars, which led to traffic jams outside terminals. Airport officials handled the congestion by requiring ride-hail vehicles to meet people at a nearby garage instead of at the curb.

Many riders blame BART’s shortcomings for making ride-hail vehicles a better deal. BART’s airport surcharge, now $4.54, goes up every time the transit agency raises fares to keep pace with inflation, making airport tickets among the most expensive for riders. A one-way Clipper fare from Antioch to SFO costs $13.15 — $13.65 for a paper ticket.

For some riders, sharing a ride-hail vehicle is a cheaper option. Uber and Lyft also provide other advantages: Cars pick up passengers from any location and operate at all times of day. And they aren’t bound to BART’s weekday schedule of 15 minutes between trains.

“That’s the tipping point,” said BART Board President Bevan Dufty. “When people have to get to a 6 a.m. flight, it’s not practical to take BART. And when you have two or three people sharing a ride, the cost is about the same.”

Dufty pressed for BART rider priority in SFO security lines after learning about a similar program in Boston, where people who take the bus to Logan International Airport get to cut in front of everybody else.

“Someone sent me a news story about the Logan (airport) trial on Twitter, and I shared it” with other transit and airport officials, Dufty said.

The airport would have to hire staff to scan BART proof of payment and manage the new security line, which might also be open to riders of SamTrans buses. SFO has also agreed to pay for several other items to enhance safety and comfort for BART riders. Among them: $300,000 for “station hardening,” which is BART-speak for locked swing gates and higher railings to discourage fare evasion; and a second airport police officer to patrol the station from 5 a.m to 1 a.m., alongside a BART police officer.

Allison said the security line program could be replicated at Oakland International Airport if it’s successful at SFO.

Additionally, SFO is on track to pay half the cost of a homeless outreach team from San Mateo County. BART would pay the other half, with the county providing services and other support. A memorandum of understanding still has to be approved by the San Mateo County Board of Supervisors.

Dufty characterized these agreements as a win for all agencies involved. A spokesman for the airport declined to comment on the new security line proposal, saying the details still had to be worked out.

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