Metered parking spots citywide can now be paid using the smart phone app MeterUP, the Philadelphia Parking Authority said Wednesday.

The app was expanded to all 15,300 paid spots in the city, PPA officials said. MeterUP use has been growing by about 2 percent a month, the PPA said, and in September accounted for 18 percent of parking fare transactions. Close to $10 million in parking fees have been paid through the app this year.

The app is managed by Parkmobile LLC, which charges users 40 cents per transaction. The app has been downloaded more than 152,000 times since it became available in Philadelphia at the end of 2017, the PPA reported.

MeterUP's payment structure makes it more difficult for a driver to linger in a spot. The app gives a user the option to renew a parking spot before the maximum paid-time period expires, but at double the original rate. And users who allow their time to expire and then attempt to renew at the original rate will be barred from using the spot. The goal, officials said, is to create more turnover in parking spots and discourage long-term street parking.

"We're hoping that you'll go to a garage and leave that spot for a delivery or someone going to a hospital," said Scott Petri, the PPA's chief executive.

A parking ticket for an expired meter costs $26.

The use of curbside space has become a growing focus of the PPA and the city, officials have said. As Center City flourishes, delivery trucks, ride-share vehicles, bicycles, and private cars increasingly congest the streets, and Philadelphia officials are in the midst of determining how to make space for all of them.

The MeterUP pay structure, though, creates a disparity for now between app users and people paying at a kiosk or meter, who don't face escalating fees to add time to a parking spot. But new kiosks to be installed will be able to charge the same kind of rising fees.

The agency put out a request for proposals for 850 new parking kiosks at the beginning of October, they said. Those kiosks, expected to be installed by September 2019, will be dispersed throughout the city to replace the original kiosks and to convert some streets from meters to kiosks. The new kiosks may be programmed with pay structures similar to MeterUPs, officials said, and will no longer allow people to pay with bills. They will only accept coins or credit or debit cards.

This move away from cash raises questions about parking access for people without smart phones or debit or credit cards.

"It's just incredible how little people understand about other people's lives," said Lance Haver, policy director of Pennsylvania Save Our Safety Net Coalition, a group that advocates for government social services.

He has been fighting to draw attention to the substantial number of people in the city who don't have access to things like bank accounts or cell phones, most recently by arguing that SEPTA's fare card creates hurdles for the poor. A system that offers coins as the only option to a card creates an added burden to the city's poor, he said. About 6 percent of the city's population does not use a bank.

The PPA is waiting for quotes from bidders to determine how much the new kiosks will cost. When the devices were last bought about 10 years ago, they cost $10,000 each. The typical price for the equipment has declined since then, officials said.

A parking kiosk can cost between $3,000 to $20,000, depending on the type of model and software package needed, according to the website Kompareit.com, which offers comparative quotes on a wide range of equipment.