How to Protect Yourself in a Multicar Pileup Caused by Fog, Snow, or Ice

Chain-reaction crashes like the deadly one on a foggy Louisiana highway are unpredictable. Here's what to do if you're in one.

The scene of a fatal pileup crash on I-55 in Manchac, La., on Monday, Oct. 23, 2023.

Whether it's on social media or TV news, it seems like every week there's another video of a multicar pileup crash on a highway. As fog, smoke, and winter weather increase the risk of severe car crashes , you might be wondering what—if anything—you can do to protect yourself from getting involved in a similar multivehicle crash, or what to do if you find yourself stuck in one.

Once a chain-reaction crash starts, it can be impossible to avoid further collisions, so it's important to recognize the risk factors for a pileup to prevent it from happening in the first place. Chain-reaction collisions tend to take place when "the driving conditions have changed because the environment has changed," says Robert Swint, CEO of ATA Associates, a crash investigation firm based in Texas that has analyzed more than 6,000 crashes over 50 years, including many chain-reaction collisions.

Swint talked with Consumer Reports in 2021 on his way to investigate a deadly pileup outside Fort Worth, Texas. He says that such crashes are usually due to sudden, weather-related changes. "It's sometimes by fog, sometimes by sandstorm, sometimes by rain, but the primary contributor is icy and snowy conditions," he says.

In those situations, drivers should try to maintain as much space around their vehicle as possible, says William Van Tassel, manager of driver training programs for AAA. "It's really hard to hit anything if you have enough space around you."

Here are some other ways to prevent a pileup—and what you should do if one is unavoidable.

Slow down and don't tailgate.When visibility drops, it can be hard for drivers to see obstacles ahead. Cars also need more distance to stop on ice and snow— even tall SUVs and cars with all-wheel drive . So drivers need to slow down in bad weather. "The slower you go, you have more time to react and more time for your vehicle to react," Swint says.

It's as easy as counting. Just look ahead down the road, find a fixed object like a telephone pole or sign, and start counting in seconds ("one Mississippi, two Mississippi") as soon as the rear bumper of the car ahead of you passes by that object. In normal weather, it should be at least 3 seconds before your front bumper passes the same object. For every "strike" against the conditions—darkness, ice, fog, precipitation—Van Tassel recommends adding another second of distance. In truly dangerous conditions, an 8- to 10-second stopping distance may be called for.

Keep an eye on your rearview mirror. You might not be tailgating the car in front of you, but what if another vehicle is riding your rear bumper? "Change lanes, adjust your speed, do whatever you have to do to let that problem driver around you," Van Tassel says. Knowing whether there's another vehicle tailgating you can also determine what action you should take if you see a crash ahead, says Jake Fisher, senior director of auto testing at CR. If you're being tailgated and come up on stopped traffic, instead of panic braking and potentially causing a chain reaction behind you, "it might be possible to slow down and change lanes or move onto the shoulder. That way if the car behind you can't stop, you may avoid a pileup."

Pay even closer attention. In dangerous driving conditions, it might be tempting to look at a navigation screen to find an alternate route or to call a loved one to let them know you're going to be late, but you need to devote your absolute concentration on driving, Fisher says. "Have awareness of where other cars are around you at all times," he says. To avoid a crash, you might have to make a split-second decision to change lanes or hit the brakes. "Having your eyes on the road means more than just looking forward—it's knowing: Is there a car next to me? Is there a car behind me?" That additional spatial awareness could be the difference between starting a pileup and avoiding a crash by driving on the shoulder. And if possible, look beyond the car in front of you to view what's happening well up the road to better react to an impending situation.

Know who you're sharing the road with. Fisher, Swint, and Van Tassel all recommend keeping a buffer around your car. In addition to not tailgating, that means modulating your speed so that you aren't driving directly alongside other vehicles. "If the car next to you loses control, they're hitting you," Fisher says. That's especially true when sharing the road with large trucks and tractor-trailers. They're often involved in pileups and can "jackknife" (when the back of the trailer swings around toward the tractor, or vice versa), taking out multiple smaller vehicles in their path. If you're stuck behind a slow-moving truck, don't try to pass it or you might end up caught in its wake if a crash takes place.

First responders at the scene of a fatal crash on I-35 near Fort Worth, Texas, in February 2021.

Don't make any sudden moves. When the roadway is slippery, even small changes in speed or direction can cause a loss of control, so you must drive slowly and smoothly. "Gradually change your speed, and don't try to abruptly change directions," Swint says. If you find yourself traveling too fast, let your foot off the gas instead of hitting the brakes. Applying the brake rapidly can put a car into a skid, where you'll also lose control over steering. "We like to say that speed is better controlled with the accelerator than the brake," Van Tassel says. "Just the slightest lift of your foot can help."

Watch the roads—literally.You know those yellow signs that say "bridge freezes before road"? They're there for a reason, Swint says. "When there's open air under the roadway, the road freezes quickly," he says, which can lead to black ice—a slippery, icy surface that isn't visible like other kinds of ice and slush. So lay off the accelerator when you approach a bridge or an overpass.

Know your car's limits. Don't confuse your vehicle's ability to accelerate with its ability to stop in an emergency. This is especially true of four-wheel- or all-wheel-drive vehicles, which tend to give drivers a false sense of security , according to Gene Petersen, who spent his career studying vehicle dynamics and recently worked as the tire program manager at CR. A two-wheel-drive vehicle might occasionally slip or slide on icy or snowy roads, letting drivers know just how little traction their vehicle has. A four-wheel-drive vehicle is more likely to stay pointed forward—but that can get drivers into trouble. "You can't stop any better, yet you may be traveling a lot faster," Petersen says. "No matter how good your tires are or whether you have all-wheel drive or two-wheel drive, your vehicle has the same four points of rubber touching the ground."

The same goes for technology, Van Tassel says. If your vehicle's traction control system activates while you're driving—indicated by an orange warning light that shows S-shaped lines behind the outline of a vehicle—that's a clear sign that you should slow down. "Just the fact that it's activated is good feedback to drivers." And although advanced safety systems like automatic emergency braking can prevent a crash, the cameras and sensors that those systems rely on often don't work if they're covered in snow, or if the road ahead is obscured by fog.

Minimize the damage. Even if a crash is inevitable, you can still take control of the situation. "There's going to be a bad outcome—it's just a matter of how bad it's going to be," Van Tassel says. On ice and snow, slamming on the brakes can put the car into a skid and cause you to lose steering and braking control. Use the brakes gingerly to slow down and try to steer into a soft object—like shrubs or a guardrail—instead of another vehicle. And keep an eye out for people who may be walking around the scene of an earlier crash.

Stay in your car after a crash. It might be a natural instinct to get out of a car after a crash, but it is best to pause before unbuckling or exiting. A two-car incident can quickly involve three, four, or more vehicles. Your crashed car is likely the safest place to be. "We've had numbers of accidents where the people who are getting killed are the people getting out of the car and who start walking around," Swint says. Even in the harried moments after a crash, drivers should take a deep breath and assess the situation. "If other cars are approaching and smashing into things, stay in your car," Van Tassel says. "Cars can offer a lot of protection to their occupants." Keep your seatbelt on, turn on your hazard lights, and wait for the crashes to stop.

When you exit, move to the front of the crash. If your car or a nearby vehicle catches fire, it may be necessary to get out of a vehicle. If that happens, and it's obvious that a multivehicle crash is still taking place, get away from other vehicles. Run forward toward the crash and then past it, Swint says—even though he says that advice may sound counterintuitive. Don't stand between two cars where you might be crushed if another impact takes place. And whatever you do, don't stand on a shoulder or in front of a guardrail or concrete barrier, because drivers may attempt to avoid the pileup by driving on the shoulder, and fast-moving vehicles often end up shunted along concrete barriers. "If you're on a bridge, go away from the flow of traffic," Swint says, because ongoing collisions can push pedestrians over the edge of a railing.

In the future, new technology might be able to prevent chain-reaction collisions. Vehicle-to-vehicle and vehicle-to-infrastructure communication allows vehicles to "talk" with each other and receive data from traffic sensors on the roadway, so your car might know to start braking if there's a crash ahead even if you can't see it through dense fog. In turn, how your car reacts could communicate vital information that can be automatically shared with other motorists. Until this technology is widespread, however, drivers will need to remain vigilant.

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