A glitch that interfered with drivers' use of credit cards to pay for Philadelphia on-street parking seems to have abated as mysteriously as it surfaced nearly a month ago.

Officials at the Philadelphia Parking Authority say the electronic kiosks that dispense short-term-parking stubs are generally working again as designed, accepting credit and debit cards as well as coins, small bills, and prepaid Smart Cards.

"It's improving, and we're glad it's improving, but no one can tell us why it's improving," Fran Westerfer, the authority's meter operations manager, said Friday.

More than 90 percent of credit-card transactions at the kiosks succeeded Wednesday and Thursday, he said, a marked improvement over the previous four weeks, when the chances of getting a credit card to produce a parking stub were closer to 50/50.

From a computer in his windowless office near 30th and Market Streets, Westerfer can follow transactions on nearly 1,000 kiosks, purchased for $10 million and installed the last two years in Center City and University City.

Typically, he said, the transactions fail only when the credit card is expired or invalid, or when its owner gets confused and bails out of the transaction.

On May 13, the pattern changed. The machines kept taking coins, small bills, and Smart Cards without incident, but up to 45 percent of the system's credit-card transactions were failing.

The kiosks would read the magnetic strips and begin transmitting the information to the banking systems that issued the cards. But thousands of times each day, the electronic transactions would time out before they could be completed.

The message to the would-be parker: "Transaction failed."

The problem continued for three weeks, frustrating engineers from several companies: Metric Parking of Marlton, the North American subsidiary of an English firm that sold more than 1,000 kiosks to the PPA; Parkeon Inc., a New Jersey company that sold the authority its first 51 kiosks; and CreditCall Ltd., a British firm that routes the credit-card transactions.

The only participant that did not officially express frustration was AT&T, which runs the wireless communications network used by the kiosk system.

An AT&T spokeswoman, Brandy Bell, issued an e-mail statement contending that the network was not to blame. "We are always happy to help investigate concerns from our partners at the PPA," the statement said, "but have found that the problem does not appear to be on our end."

"I wouldn't put a whole lot of stock in that," Westerfer said midweek. "We still have problems, and no one has told us yet what the cause is or how it will be fixed. . . . Right now it's up in the air. Nothing has been established."

As suddenly as the problem began, the situation seemed to return to normal toward the end of the week.

"I think all the engineers are scratching their heads," said Dave Witts, president of Metric Parking.

"We don't consider this closed," said Peter Turner, CreditCall's chief executive officer. "Something's happened, and unless we can find out what has happened, there's always a feeling it's lurking out there."

Some wary drivers figure that it's smarter just to maintain a supply of quarters. "I gave up on my cards maybe six or seven months ago," said Arlene Freedman of Bala Cynwyd. "I was over near the Free Library. I tried both my Smart Card and my credit card, and I couldn't get any of them to work. Now I just carry dollars and quarters with me. I figure these kiosks are something they've perpetrated on the citizens to make them crazy."

Contact staff writer Bob Warner
at 215-854-2611 or warnerb@phillynews.com.