In Erie and other cities, a smartphone user can report potholes or graffiti simply by snapping and sending a photo to the authorities. The phone's locational data do the rest.

In Washington, an app allows users to view crime reports around any location, to see just how risky that late-night walk home might be.

In Baltimore, motorists can find out how likely they are to get a parking ticket in a particular spot if they linger past their allotted time.

Public agencies have always collected and used vast amounts of data, while offering only a small fraction of it back to the public - often in less-than-user-friendly ways.

But in the last several years - spurred by the spread of smartphones such as Apple's iPhone - something unexpected has been born: a largely organic public-private partnership, in which agencies make data more easily available, and app developers use the data to try to make money by making people's lives easier and more efficient.

SEPTA hopes to join the burgeoning movement this weekend. With Devnuts, a self-described "hackerspace" in Northern Liberties, the transit agency is cosponsoring a "hackathon" aimed at quickly producing apps that utilize SEPTA's wealth of real-time operational data.

About 25 to 30 people are expected, and you don't need to be a software geek to participate, says Mark Headd, a Wilmington resident who has worked both sides of the government-business divide. Headd once advised Delaware's governor on information technology. Now he's a developer for a Florida company, Voxeo, and has helped organize half a dozen hackathons here and elsewhere.

"I've been at many hackathons where it's a nontechnical person who has contributed the idea that has made the difference," Headd says.

Transit data are a common focus - tens of thousands of people use the systems daily and need to know about schedules, delays, and the like - but Headd won a silver medal at a Washington hackathon for developing the smartphone app that maps crimes in a user's vicinity.

What's the reward? The medals and prizes are of minimal value, in line with the $10 registration fee. Headd says the real return comes from the chance to improve your community and, perhaps, to do well by doing good.

At the end of the marathon weekend - Headd says participants sometimes arrive with sleeping bags - the hackathoners will own what they produce. Some may eventually sell their inventions via Apple's App Store or Google's Android Market.

Nor are smartphone apps the only possible result. Though the new movement has been spurred by the growing ubiquity of those powerful handheld computers, Headd says, a valuable SEPTA app might simply enable a coffee shop to install a window display showing commuters when the next bus will arrive.

"People might want to stay and say, 'Hey, I'll have a cup of coffee and a sandwich, because the next bus isn't coming for 15 minutes,' " he says.

This isn't SEPTA's first experiment with using outsiders to supplement its own IT brainpower. Earlier this year, developers from the nonprofit Code for America helped build a prototype site,, for display on touchscreen devices.

Code for America also helped create a Web and smartphone app, MuralApp, that shows where murals and other public art are on display in Philadelphia - great for giving tours to visitors. But the biggest public-private collaboration here so far is, managed by Azavea, a local company that is developing an online catalog of Philadelphia data and promoting innovative civic apps.

Mike Zaleski, SEPTA's director of emerging and specialty technology, says this weekend's hackathon was inspired by the idea that private developers can help their communities by finding new ways to use public data.

"They can be a little more agile in consuming it and putting these products out to the public. In the end it benefits our riders," Zaleski says.

And it benefits everybody else, adds Headd, by reducing traffic, pollution, and greenhouse-gas emissions.

"If people can open up their smartphones and find out exactly where the train is going and when it's coming, they're more likely to take it. Public transit can be intimidating and confusing. And like so many other things, technology can make it infinitely easier to use."