Heather Rossignol was driving on the Maine Turnpike in Scarborough on Sunday, headed to the Portland jetport, when a huge slab of ice suddenly flew off another car and smashed into her windshield.

“I kind of held my breath and ducked a little bit. I didn’t know what to do,” Rossignol said Monday. Shards of glass sprayed her and the passenger seat as her windshield fractured into an opaque web of cracks as her 7-year-old son, David, watched from the back seat.

“I managed to stay in my lane on the road and stay calm,” she said, relieved she didn’t crash.

Maine State Police say at least 20 cars were damaged by ice that blew off vehicles that weren’t cleared of the ice-encrusted snow left by Sunday’s storm.

The damage, most of it south of Portland, was reported on the interstate highways and on the turnpike Monday morning, police said.

Rossignol could see through a small corner of the windshield on her 2013 Chrysler 200 and was able to pull off the highway at the Maine Mall exit.

“I didn’t know what to think about it at first, and then I really looked at my car and said this could have been a lot worse,” she said.

Lt. Erik Baker, head of the state police turnpike barracks, said the weekend storm created ideal conditions for the hazard, with a light snow followed by rain and then freezing temperatures. Though he knew of no injuries, the flying ice did do significant damage to some vehicles.

“Mostly what we’ve seen today are smashed windshields and some of the vehicles also have their grills smashed,” he said.

Cleaning snow and ice off a vehicle’s roof is an important precaution – though not a legal requirement, he said.

“There’s a statute that says we have to have windshield and side windows and the rear window clear of ice and snow, but there’s no specific statute that says you have to clean the roof of a vehicle off,” he said.

Other states, including Connecticut, New Jersey and Pennsylvania, do have laws requiring drivers to clear roofs, trunks and hoods of snow. Massachusetts and New York have debated similar legislation, according to the website of the trade group American Trucking Association. However, in some states the rules apply only to commercial vehicles, or only kick in when the falling ice has injured someone or damaged a vehicle.

Legislators on Maine’s Transportation Committee say there have been proposals in the past, most recently in 2011, mainly dealing with tractor-trailers. None of the proposals became law, and the 2011 bill died in committee.

“It’s a situation of just common sense. You would want to clear your vehicle so it’s not a safety hazard,” said Sen. Ronald Collins, R-Wells, co-chair of the Transportation Committee. “They always tell me up here you can’t regulate common sense.”

Andrew J. McLean, D-Gorham, the House co-chair of the committee, said enforcing a law requiring car roofs to be cleared would be a challenge.

“What is a significant amount of ice? What is a significant amount of snow? The police during snowstorms and ice storms have a lot of responsibility to begin with,” he said. “With any storm we all have a responsibility to make sure our windshield and our roofs are clear and safe, not only for ourselves, but for all the drivers on the road.”

McLean said he saw chunks of flying ice on the turnpike Monday, but believes people are generally responsible about clearing off their cars.

Collins and McLean both said the issue has not been raised by constituents.

Diane Maines of Portland said she was anxious on the highway Monday, remembering a dangerous encounter a few years ago when a tractor-trailer passed her on the turnpike between Falmouth and Gray.

“I could see the sheets start to peel off the back of his truck,” she recalled Monday. “There was a car in front of me and one behind me. There was, like, nowhere to go, and this giant sheet, 5 feet wide by like 3 feet, was twisting in the air and it’s coming at you like 65 mph.”

Maines said the incident felt as though it were occurring in slow motion. Then the ice hit.

“It obliterates my windshield,” she said. She was showered in small glass fragments and felt fortunate that she didn’t wreck.

“I literally couldn’t stop from hitting the brake when this happened. You’re like blind,” she said.

Tim Doyle, of the trucking industry group Maine Motor Transport Association, said clearing snow and ice off a truck roof is difficult.

“It’s not as easy as someone taking a broom and sweeping off the car before they leave. For the safety of the driver, they can’t just climb on the trailer,” Doyle said.

Doyle said drivers are encouraged to check their roofs because they are responsible for anything that comes off the rig, including ice and snow.

Trucking companies can hire a service to clean off truck roofs, and some larger companies have devices that scrape the snow and ice off trucks driven beneath them.

Workers at Hartt Transportation Systems in Bangor built their own truck-scraping structure after the company discovered it was spending “more than tens of thousands of dollars” to have trailer roofs cleared off, said chief financial officer Joanna Bradeen.

The company is installing a scraper at its new facility in Auburn and plans to market the service to other trucking outfits.

Clearing snow and ice from a car roof can be easily done with a broom.

Alternatively, Justin Smith of Freeport Hardware said many customers buy an extendable scraper with a rigid foam blade that dealerships use to clean off their cars.

And clearing one car only takes a few minutes.