Metro bus and rail passengers know the drill: To ride, they need a plastic TAP card to swipe a train station turnstile or on-board bus fare reader.

For low-income passengers who qualify for Metro’s fare reduction program, getting the discount they are promised involves using paper coupons, standing in line at a grocery store and waiting for the clerk to complete the transaction using outdated card readers.

To make things go smoother, Metro, along with 24 other transit agencies in Los Angeles County, have switched to an Android-based reader installed at 457 third-party locations — Ralphs grocery stores, check-cashing businesses and convenience stores.

The new system, created by Cubic Transportation Systems of San Diego, will access a rider’s TAP card account and immediately know if the rider is registered for the low-income discount or others, such as senior citizen, disabled, K-12 student or college student, said Robin O’Hara, Metro executive officer for TAP.

Once the reader plugs into the person’s account, the discounts will automatically apply and the vendor won’t have to deal with paper coupons or wait for reimbursements from Metro. Or, the passengers can buy a TAP card for $2, add a weekly or monthly pass or cash value to the TAP card — all without going to a vending machine at a train station.

“It is a modern interface. It is faster for the customer, too,” O’Hara said.

Buying a TAP card or adding value has always been a service provided by a group of store-based vendors. At one time, they sold tokens, but they have been eliminated by Metro. By July 1, nearly 100 percent of the vendors will have received the new equipment, O’Hara said.

“This is more of an upgrade of equipment, some of which is 10 to 15 years old,” said Josh List, senior program manager for Cubic Transportation Systems.

“This will streamline everything for them,” List added.

Riders cannot apply for senior transit passes at the third-party stores. That still must be done in person at the transit system customer service office or online websites. But now, the computerized readers can determine more quickly what passes or discounts are on the cards.

In addition, the Los Angeles County Metropolitan Transportation Authority is considering using the new system to provide special fare discounts in low-income ZIP codes or on a particular train or bus line, O’Hara said.

Other transit agencies using the TAP cards include Long Beach Transit, Torrance Transit, Pasadena Transit, Foothill Transit, BurbankBus and Palos Verdes Peninsula Transit Authority.

Cubic will receive 0.75% from each transaction. As an incentive to install the card readers, a store receives 3.75% of each transaction as commission, O’Hara said.

Metro has seen an uptick in the number of third-party vendors with card readers, she said.

“Retailers make a small commission, yes, but mostly they do it to drive traffic into their location,” List said.

O’Hara said the new devices take up less space on a store counter. “It will be much easier to get vendors to sell the fare products,” she said.