Irish Rail is today launching its long-awaited e-ticket system.
It means passengers no longer need to print off their tickets when travelling on intercity routes.
Passengers who book online or through the Irish Rail app will now be emailed a QR barcode that can be scanned at barriers.
The company first announced the move on The Anton Savage Show last weekend.
The system is now available on all intercity routes except the Belfast line.
There will be no changes to ticket prices with the introduction of e-tickets.
Irish Rail Corporate Communications Manager Barry Kenny said it is good for customers and the environment.
"You go to the barrier same as ever, but you're saving that bit of time not having to print tickets off," he said.
"We have up to four million tickets printed per annum, so the sustainability benefits of this will be very, very significant as more customers choose the QR code and leave the printed ticket behind.
"The need to print out tickets is no more [but] it's still there if you choose to do it.
"If you choose the QR code you can simply scan your QR code at the barriers".
Mr Kenny said the QR codes will also allow customers to make more changes nearer to their journey, depending on their ticket type.