Shopping carts fit snugly into that class of things considered useful in their proper environment, but ugly and annoying when they go astray. And too often, they go astray.

Tom Riel, mayor of Bradford, remembers not long ago counting 28 shopping carts abandoned along a one-mile stretch of road in his McKean County community. Some ended up in a stream that flowed toward New York state.

"It tarnishes the image of a community," Mr. Riel said in a recent telephone interview.

Efforts to keep carts on the straight and narrow have stepped up a notch in recent years, especially in places where consumers find it tempting to put them to creative uses or just like the convenience of carting groceries right to their front door

(This is, of course, a separate problem from the aggravations shopping carts can cause inside stores -- wheels that stick or squeak or go off in their own direction.)

In the great outdoors, the concern is keeping abandoned carts, which can cost $100 apiece, from becoming neighborhood eyesores. The issue hasn't reached the public awareness level of plastic shopping bags in the environment, but stray carts have been a common enough problem to inspire some get-tough policies.

Retailers trying to protect their investments are installing locking cart wheels that respond to radio frequency signals, and exasperated communities are stepping up fines for either stores or customers who break the rules.

In 2009, at least 17 cities nationwide enacted ordinances involving shopping carts, according to Karryn P. Gleckner, marketing communications manager for Gatekeeper Systems, an Irvine, Calif., company that makes cart containment systems. Those are the ones that she knows about, anyway; she started keeping track last year.

Gatekeeper, which claims to have "contained" 1.4 million shopping carts worldwide, was founded in 1998. Business has grown about 30 percent a year for the past five years, Ms. Gleckner said.

Carttronics, a San Diego company founded in 1997, is another big name in shopping cart containment systems and is currently involved in a test being run by O'Hara-based grocer Giant Eagle at 13 locations, including some in the Pittsburgh area.

At one test store, the South Side Giant Eagle, a recent visit found several carts at the edge of the parking lot. That might not seem unusual except that a push on the handles makes it clear these carts aren't going anywhere fast because one wheel has locked up.

In this particular system, an underground electric fence has been installed. From above, it looks like a couple of lines cut into the pavement. Meanwhile, each of the store's carts has been fitted with one wheel with a battery-operated sensor that locks when a customer gets within 2 feet of the fence, according to a company spokesman. Shoppers are alerted to the presence of the locks with signs near the store and in the carts.

For carts that cross the line, a yellow-vested employee later comes around with a hand-held device that sends a signal to unlock the wheel so the cart can be returned to the store.

"From a cart loss perspective, systems such as these have proven to be effective," Giant Eagle spokesman Dick Roberts said in an e-mail.

In general, they are not inexpensive. Ms. Gleckner, at Gatekeeper, said the cost of the system averaged about $18,000, although it can range from $6,000 to $50,000 depending on the size of the parking lot perimeter.

Nationwide, she said, such systems were in use in a variety of retail operations, not just grocery stores. Some chains have a policy of keeping track of cart losses, and once a store location has proven to exceed a certain level, the chain starts looking at ways to address it, she said.

There's general agreement that losses tend to be exacerbated by a couple of different factors. One is weather. "Generally, we see [that] the warmer temperature cities are often the ones that have ordinances," Ms. Gleckner said.

Indeed, states such as California and Florida pop up as among those with the highest concentration of ordinances. Los Angeles was reportedly studying the problem this spring.

But, according to Gatekeeper's list, there are also a significant number of ordinances in place in New Jersey, New York, Massachusetts and Michigan. Even Pennsylvania is shown as having 10.

Urban areas with a high concentration of nearby residences also can see high shopping cart losses. While that sometimes means low-income areas, it's not always the case. It can be as much about transportation as income: It's just easier to get the groceries to the closest bus stop in a cart.

Warehouse club operator Costco would rather not use cart containment systems at all, said Jeff Long, senior vice president for the chain's Northeast region. "They work, but they are extremely irritating," he said.

Customers don't like the experience of having a wheel lock up, and sometimes, he said, the wheel just locks up because the battery died. That's especially annoying.

That said, Costco has found in some dense residential neighborhoods around the New York City area, too many customers decide to push their carts home. To try to avoid that, he said, "We do have them in a couple of our inner-city stores."

The expense of locking-wheel systems are among the reasons city ordinances generally don't specifically require them or indeed prescribe any particular solution. Retailers are left to figure that out -- and face sometimes hefty fines if they don't.

It's not as if they haven't been trying to deal with the problem for years anyway.

Jack Kirchartz, operations manager for Zampogna Carts Inc. in Arnold, has seen his retail customers try all sorts of things to keep their shopping carts from wandering. Zampogna sells replacement carts, in addition to providing maintenance services such as cleaning and repairs.

One customer in Cleveland loses 1,500 carts a year. "I don't know where they go, but they don't come back," Mr. Kirchartz said.

He's not a big fan of locking wheel systems. Sometimes, he said, customers just keep pushing and "flat spot" the wheels, which then have to be repaired. That also can happen if employees on cart retrieval duty shove along a group of carts not realizing that some wheels have locked.

A basic wheel for a cart costs about $5, and Zampogna, which has clients in other states and refurbishes used carts, goes through 50,000 to 60,000 wheels a year.

Aldi, the German-owned limited assortment grocery chain, has made a 25-cent deposit for its carts a part of the shopping experience, and customers don't seem to mind. They get the quarter back when they return the cart, and the retailer doesn't have to pay staff to chase carts.

A Foodland store in the West Mifflin area didn't do as well when it tried installing a similar system a few years ago, Mr. Kirchartz said. Zampogna installed the locks.

A month later, he got a call asking if he'd like to buy back the lock boxes because the store had lost customers. "I've never seen it work here," Mr. Kirchartz said.

Other retailers have attached poles to carts so they won't fit through the store's doors. There are also retailers with bollards installed around the edges of the front sidewalk. Customers can pull up their cars and load up but they can't take the carts into the parking lot.

Stray carts aren't just a problem because they cost money to replace and trash up a neighborhood. They also can roll into traffic or into parked cars and cause damage.

For most stores in Western Pennsylvania, Mr. Kirchartz recommends friction wheels, which will go through two rotations and then stop if a cart isn't actively being pushed. "It makes it a little harder to push," he said, but it can combat the pull of gravity on Pittsburgh's often hilly parking lots.

For now, there's little indication that one old-fashioned technique to combat shopping cart losses is going away.

Shop 'n Save does not have cart restraint systems in place at stores in this region, according to a spokesman. But in some inner-city neighborhoods, staff are sent out to retrieve any wayward carts.

That's what Giant Eagle did before testing the locking wheels, Mr. Roberts said. Store employees were sent out to walk the neighborhood every week or two. At this point, he said, "We have tentative plans to continue the use and expansion of the program" in locations prone to cart losses.

Meanwhile, in Bradford, Mr.Riel is pleased with changes he's seen in the past two years or so.

As a public official, he thought keeping shopping carts off the streets was a priority along with other quality-of-life issues such as banning smoking in public parks and cleaning up after pet dogs.

For years, Bradford police couldn't stop people with carts because stores didn't report them as stolen. And they weren't inclined to offend customers.

After some debate, Bradford made it illegal in 2008 to remove a shopping cart from a store's premises without written permission.

"It was even more effective than I thought it would be," Mr. Riel reported. Many people who walk to the grocery store invested in collapsible carts to get their groceries home, and he reports 95 percent of the problem has gone away.

He's still keeping an eye out. "I just stopped a guy a couple of weeks ago, and he had his written permission."

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