Unable to attract any bidders for new taxicab licenses at $475,000 each, the Philadelphia Parking Authority on Tuesday lowered the asking price to $350,000.

The PPA board approved the lower price after 20 new taxi medallions, which are to be used for wheelchair-accessible vehicles, went unsold at auctions in the last month.

Taxi medallions, which are required to operate a cab in Philadelphia, skyrocketed in value in recent years, going for as much as $545,000 in private sales earlier this year, up from $65,000 in 2005.

But the arrival of UberX, the ride-sharing service using private autos hailed by smartphone, has disrupted the taxi business and threatened the value of the medallions.

The PPA planned to sell 46 new medallions this year, in an effort to increase the availability of wheelchair-accessible taxis.

But the first-ever auctions of new medallions by the PPA came just as UberX was launching its ride-sharing service in Philadelphia, in defiance of a ban by the PPA. The Parking Authority oversees the cab industry in Philadelphia.

Uber, a San Francisco-based company, connects people looking for rides with private car owners looking for extra money. Uber's phone app allows riders to summon a car, pay for the service, and get a receipt, all electronically.

The new, lower-priced medallions will be offered at auctions that will start in about two months, after a required public-notice period.

pnussbaum@phillynews.com

215-854-4587 @nussbaumpaul