Maria Barlow brought home an unwanted souvenir from her summer vacation in Tempe, Ariz.: a parking ticket.

She had left her rental car in a touristy neighborhood near Arizona State University, in an area not clearly marked as metered. When she returned to her vehicle, Barlow found a $57 ticket from the city.

“Tourists are sitting ducks,” she complains.

Barlow, a lawyer from Chicago, says she believes that rental cars with out-of-state plates are often targeted for enforcement. She paid the parking ticket quickly instead of fighting it.

Her experience is becoming more common as parking enforcement rebounds. Patrick Murray, CEO of the parking deal website On Air Parking, estimates that enforcement activities, including issuing tickets and utilizing immobilization devices, were down between 50 and 80 percent in the months that followed the covid-19 outbreak.

“We started to see parking enforcement divisions come back to the office in June,” Murray says. “After an initial waiver of meter fees, most had a staged approach — to reactivate meters, begin meter enforcement and to enforce the scofflaw list.”

Parking tickets were a growing source of revenue before the pandemic. The auto rental site CarRentals.com recently estimated the parking enforcement revenue from 16 major U.S. cities to top $1.4 billion a year. The big city that collects parking fines most aggressively is San Francisco. It collected the equivalent of $111 in fines for each resident. Chicago and D.C. came in second and third, respectively, pulling in $99 and $97 per resident.

Drew Cheneler, a government employee from D.C., has received so many parking tickets on vacation that he has started to research parking spots when traveling. Downloading apps such as ParkWhiz, Parking Panda and SpotHero has helped him find parking spots so he doesn’t have to hunt for spaces that may or may not be legal.

As a repeat offender, his advice for avoiding tickets is simple: “Make sure you park legally, and make sure to carry around some spare coins so you can pay for a parking meter,” says Cheneler, who also publishes a personal finance blog.

Parking regulations are a chronic problem for out-of-town motorists. It’s easy to misinterpret — or just plain miss — a “No Parking” sign when you’re distracted and don’t know the territory. Travelers like Barlow, who get nothing worse than a ticket, may be the lucky ones. The unlucky ones get a vehicle immobilization device.

Zachary Stafford, a professional house sitter based in Los Angeles, tells of getting a wheel clamp — also known as a “Denver boot” — in Ireland recently. “I was parked one spot away from what was deemed the appropriate designated parking location,” he says.

Stafford called the number on the clamp, forked over his credit card number to pay a $100 fine, and then waited in the rain for someone to come and free his vehicle.

Later, Stafford fought the charges on his credit card.

“I took pictures of everything — the signs, where I parked, screen shots of how I paid via an app that directed me where to park, the clamp, you name it,” he says. “Then, when I got to my destination, I applied for an appeal through the website. It took three months, but I got my $100 back.”

Closer to home, consider what happened to Fred Zoepfl in Northern Virginia recently after an event near the Tysons Galleria mall. He found a bright yellow plastic device called a Barnacle covering the windshield of his car.

Several commercial-grade suction cups held the device in place. A swipe of his credit card on the Barnacle paid a $75 parking fine and released it.

“We considered ourselves to be paying customers of a business in the mall, and we thought we could park anywhere in the mall parking lot for a few hours,” says Zoepfl, a retired nuclear engineer from Ashburn, Va. He and his wife had parked at the mall and had dinner there before attending a nearby event.

Rich Dinning, the senior general manager of Tysons Galleria, says anyone using its parking facilities must remain on the premises at all times. “Without this policy in place, our parking garage would quickly fill, and we would no longer be able to offer Tysons Galleria guests the convenience of free parking,” he says.

The episode had a similar ending to Stafford’s in Ireland. Zoepfl disputed his credit card charges, arguing that he was a paying customer at Tysons Galleria. His credit card company sided with him, reimbursing him for the $75 fine.

Zoepfl says he would have scraped the “monstrosity” off his car if he could have. He later found several online discussions that offered step-by-step instructions on how to safely remove the Barnacle. The company says 3 to 5 percent of people impeded by the Barnacle try to remove or destroy the device.

But his experience points to a much better solution. Instead of trying to disable a Barnacle or a wheel clamp, you’re better off taking pictures of the scene and fighting the fine later. Or better yet, just plan ahead — and park legally.

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