Outdoor dining was meant to help save ailing restaurants around the country from financial disaster during the coronavirus crisis. But it's customers who could be sitting in harm's way.

As an alternative to indoor dining, many cities have allowed eateries to set up tables in parking lots, on sidewalks or in fenced-in areas directly on streets in the belief that fresh air can help defeat the coronavirus. The problem is cars showing up as uninvited guests.

A group that informally tracks incidents of vehicles crashing into buildings or crowds based on media or police reports, the Storefront Safety Council, so far has counted about 20 instances of cars or trucks barging into outdoor dining areas since restaurants reopened after COVID-19-related shutdowns. That compares to about four a year over the past eight years.

"Clearly, we are already seeing a big spike in an eight-week span," said Rob Reiter, co-founder of the group.

While the goal of giving restaurants another way to survive beyond offering takeout meals may be noble, the jury is out on whether they are doing it safely.

On Friday, one of the incidents turned deadly. A high-speed police pursuit in Cincinnati, Ohio, police crossed into Kentucky. The suspect car jumped a curb and crashed into several people outside of the Press on Monmouth cafe in Newport, killing two and injuring two others.

In New York City, five people were injured July 5 when a driver crashed into the outdoor seating at 12 Corazones restaurant in Queens, with video of the incident receiving widespread attention. Another crash occurred July 23 when a truck tore through outside tables at the L'Wren restaurant in Brooklyn, according to multiple news reports.

Most vulnerable are tables being set up in streets, sometimes with vehicles passing feet away.

"The closer the proximity to traffic, the greater the risk will be," Reiter said. "In the best of times, there is some risk associated with sidewalk dining, curbside dining, and street closings. This is not the best of times."

Any space that mixes diners at tables with moving vehicles spells trouble, said Victor Manalo, former mayor of Artesia, California. He knows first-hand: His mother-in-law was killed in 2014 when a man driving an SUV jolted forward out of a parking space, striking her and others outside an ice-cream parlor. 

Manalo has been on a crusade on the issue ever since, including consulting to a company that makes bollards -- those large metal pipes that rise out of the ground -- for parking lots. Street dining spaces, he said, are no match for a moving car even when there are low posted speed limits.

"All it takes is a distraction for you to veer off to one side and crash into one of those," Manalo said. 

Cities have taken different approaches when it comes to protecting dining areas in streets, even those in the same metro area. In Los Angeles County, restaurants along Main Street in Santa Monica have concrete sections around street dining, those in Culver City and Long Beach are protected by water-filled barricades.

For its part, the city of Los Angeles' Department of Transportation is supplying large planters paired with freestanding metal railings that look like bicycle racks to restaurants under a program called L.A. Al Fresco.

Restaurant owners say they believe outdoor dining is safe and plays a role in trying to keep their businesses alive.

In the city's Westchester neighborhood, chef Vanda Asapahu at Ayara Thai Cuisine said the city provided not only planters and railings, but reflectors so the setup is more visible to drivers at night. Westchester has a "small town-like feel to it" and the restaurant is on a low-speed street with minimal traffic, she said in a statement.

And, she said, outdoor dining has been popular.

"Our returning customers love the new outdoor dining option as it's something we've never had before in all the years that we've been open." Asapahu said.

Across the city in Larchmont Village, Steven Cohen said the temporary outdoor dining area in the street in front of his family-run Village Pizzeria has been a slice of good fortune against the overwise dreary 70% drop in sales due to coronavirus restrictions. 

The dining area -- the city even supplied umbrellas -- is helping keep the business stay afloat after 28 years even as stores around him on Larchmont Boulevard close. Cohen said he won't sacrifice safety and he didn't proceed until his insurer extended his policy to cover outdoor dining.

"We are exercising great caution, which we always do," Cohen said.

It's not just restaurants with tables on streets that could have an issue, but those with dining spaces in their parking lots.

The owners of Nellie's Place in Waldwick, New Jersey, put their outdoor seating area behind the restaurant. But even that precaution didn't stop a driver who was feeling ill after taking a test for COVID-19 from passing out behind the wheel and having her car go out of control. It hopped a curb and didn't come to a stop until it barreled through the parking lot, ripped through the seating area and struck a dumpster, said co-owner Chris Roche.

The accident would have occurred during what normally would be the lunch rush. But on that day last month, the restaurant had closed due to a tropical storm, so no one was in harm's way, Roche said. 

The incident was harrowing enough that Roche said they installed 700-pound barriers.

"We've been here 40 years. Whoever would have thought it could happen in our rear area?" Roche asked in an interview.

One of the nation's top transportation experts, James Moore of the University of Southern California, said outdoor eating areas aren't likely more dangerous than dining inside behind a plate-glass window in a restaurant. Cars can crash into either. Plus, the presence of pedestrians outside could make drivers more cautious.

"If there is a danger from eating outside, it is likely being closer to fine particulate matter in vehicle exhaust and tire shedding," Moore said in a statement.

Another expert, however, Donald Shoup of the University of California, Los Angeles, said that perhaps cities should consider applying some of the ideas that they have used for "protected" bike lanes to make street dining safer. In particular, a row of parking could be moved outside of them to provide a barrier against traffic.

But one insurance risk-control consultant, Keven Moore of the Houchens Insurance Group and no relation to James Moore, said in an interview that dining areas in streets still remain too close to passing cars. The threat comes not just from inattentive drivers, but those who might want to deliberately cause harm.

"Restaurants are trying to survive. I get it. You have local leaders trying to help them," Moore said. But "you can't take safety out of the equation."