PHILADELPHIA (CBS) – As SEPTA works on replacing old regional rail cars by the end of next year, the latest cars to be added to the system aren’t ready to roll yet.

SEPTA is buying 120 state of the art Silverliner V cars from a South Korean company. One three-car pilot train has been running on the commuter rail system since October.

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Three more cars were supposed to be ready Friday but have been delayed three to four weeks after production problems were encountered at the South Philadelphia facility where final assembly of the cars is being done after being shipped from South Korea.

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The new cars are being purchased by SEPTA for $274 million.

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Reported By John McDevitt, KYW Newsradio.