Port Authority has halted the installation of new bus fareboxes because of a problem with currency jamming in the machines.

So far, 127 of 167 buses operating from the Ross garage have gotten the new boxes. Nearly all have experienced a problem the authority is calling "phantom bill jams" in which the boxes delay verification that the bills are genuine.

The problem was affecting about 3 percent of transactions, causing delays for passengers. "That's not acceptable," said Tim Bach, the authority's project manager.

He told the authority's performance oversight committee today that software changes appear to offer "a promising start" to correcting the jamming problem. Solutions have been found for other startup glitches, including the capacity of vaults that are being installed at the garages to receive the farebox money.

The new fareboxes are part of the authority's $32.2 million conversion to a smart card fare system in which many riders will use plastic cards with an embedded computer chip.

Board member Mavis Rainey said she has heard several complaints from riders about the new fareboxes, which are more discerning about the currency they will accept. The old boxes were not designed to detect counterfeit money and do not reject heavily damaged bills.

"There will always be some issues associated with the bills," Mr. Bach said. He said riders will need to adjust by having bills that are in good condition. Authority officials have compared the fareboxes to vending machines in their reluctance to accept weathered or torn money.

He also said that when smart cards are implemented "the use of cash will go down significantly."

Mr. Bach said he hopes to resume installation next month and that the delay will not affect the overall project timetable, which calls for smart cards to be in use by year's end.

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