The supermarket group is introducing self-scanning, which enables customers to price their own shopping with plastic, space-age "guns". The "Shop and Go" scheme means that they can whiz through tills without the bother of unloading and repacking the trolley.
The scheme has been tested in 24 of the group's 370 shops. It will be extended to a further 36 by August and then be rolled out nationally.
Safeway's marketing director, Roger Partington, said: "We know our customers want to spend as little time as possible at the check-out. Shop and Go has been extremely successful at addressing this problem."
Only shoppers who hold Safeway's ABC loyalty card qualify to use the scheme (the card has 3.5 million members). On entering the store they use their card to collect a hand-held unit called a Handiscan.
Taking a trolley and the Handiscan, which looks like a mobile phone, customers shop as normal but scan the bar code on each item they want by pressing the "plus" button on the handset. If they change their mind about a purchase, they press the "minus" button and it is deleted from the list.
Goods are put straight into green boxes and after paying at the check- out using the loyalty card, the boxes can be lifted out of the trolley and into the car.
The scheme seems open to abuse from the unscrupulous, but Safeway denies that it is a "shoplifter's charter". It says random checks are carried out to ensure customers have scanned their goods correctly.
"We have their card and their names and addresses. All the evidence shows that when you have someone's name and address, they don't steal."
Safeway has caught some customers trying to "sneak through" a couple of bottles of wines or spirits, but says most are accurate and, if anything, pay too much. The company also says that shoppers who use the handsets tend to spend more than they normally would.
However, the scheme could backfire as some shoppers have felt embarrassed after making genuine mistakes. One shopper who had charged himself pounds 10 less than the true bill said: "It was an innocent mistake but it made me feel like a shoplifter. I felt stigmatised."
Unions are concerned that self-scanning will be used by Safeway to cut the number of check-out jobs. But Safeway says that the scheme will have no impact on staff levels: any jobs lost at the check out will be redeployed elsewhere on the shop floor.