On Monday, a large cloud of fog enveloped a highway leading to at least 158 car crashes and seven deaths in the southern US state of Louisiana. The so-called “super fog,” which US media reported was caused by a mixture of marsh fires and dense fog, led to a massive pileup on Interstate 55, about 30 miles (48 kilometers) outside New Orleans. Traffic slanted as drivers struggled to see other cars and trucks. The resulting wrecks left a long stretch of scorched and mangled vehicles, and authorities warned that the death toll could rise as first responders sift through the debris.
The deadly conditions developed in southeastern Louisiana on Monday morning when smoke from ongoing wildfires and dense fog created treacherous driving conditions. The fog is notoriously difficult to overcome on highways because it reduces visibility to near-zero levels, hindering a driver’s ability to react to changing conditions on the roadway. The National Weather Service described the hazy condition as super fog. It can be dangerous when it mixes with smoke from ongoing wildfires and can drop visibility to less than 10 feet (3 meters).
Local media reported that the fog developed along Interstate 55 in St John the Baptist Parish, northwest of New Orleans, where fires burned in dry marshland. The smoke from the smoldering material and water vapor released by the smoldering material and cooler air produce the fog. The National Weather Service said the combination can reduce visibility to less than 10 feet (3 meters) for up to a mile.
One witness told local media that she heard the sound of crashing vehicles for at least half an hour as cars slammed into each other on the highway. She said a tanker truck carrying hazardous liquid was also involved in the accidents and was destroyed by fire at one point. School buses were brought in to transport stranded motorists from the scene of the multiple collisions, which had police closing the highway for several hours as they worked to clear it.
As the sun set on Monday, dozens of cars were piled up in both directions on Interstate 55. The smell of burnt wreckage hung in the air as state police said they had not yet been able to locate all of the victims. They were waiting for a damaged tanker to be off-loaded from the crash site before they could fully assess the scene and were anticipating additional fatalities as they sifted through the mangled cars.
The incident occurred in a part of the interstate that runs between Ruddock and Manchac, about 35 miles (56 kilometers) west of New Orleans. The fires were reportedly spreading into the surrounding area, and traffic was closed nearby. Authorities urged residents to evacuate from the area because of the dangers presented by the fires and the fog, which they said could remain for another week or more.