CHICAGO (CBS) — The CTA’s switchover to the new Ventra fare system was hitting a major milestone on Monday, as the agency stopped sales of its old magnetic-striped fare cards at train stations.

CBS 2’s Mike Puccinelli reports the old fare cards will still be accepted at L station turnstiles and on buses until December 15, and can be reloaded through Nov. 15.

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Approximately 75 percent of CTA riders still use the magnetic-striped fare cards, so the switch to Ventra amounts to a big change for hundreds of thousands of commuters.

“It takes a little longer than the old system,” said commuter Edward Sweeney. “I’ve been using it for about a month-and-a-half now. It takes, on average, probably three or four seconds longer.”

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Also Monday, riders who use Chicago Cards will no longer be able to reload or add value to those cards. Chicago Card Plus users, however, can continue reloading their cards until Nov. 15.

The CTA has been mailing out new Ventra cards to registered Chicago Card and Chicago Card Plus users. Those two types of card will no longer be valid on the CTA on Nov. 15. Any remaining balance on a Chicago Card, a Chicago Card Plus, or a magnetic-stripe fare card can be transferred to a Ventra card through March 31.

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Extra employees will be at all CTA stations on Monday to assist customers who need help figuring out how to buy the new Ventra contactless cards.