Whether it's a dust storm in Arizona, a whiteout in Maine or wildfire in Florida, the call to shut down a major highway usually rests with local officials, who in some cases have little, if any, written guidelines to follow.
In many cases, officials rely on what officers at the scene are seeing — or what they can't see — when they make the decision. In Florida, a foggy, smoke-filled stretch of Interstate 75 in Gainesville was closed in both directions for three hours early Sunday. Shortly after troopers decided to reopen the highway, cars slammed into tractor-trailers on both sides of the interstate in two pileups that killed 10 people.
Florida officials said they were willing to review their protocols, but the Highway Patrol was also quick to put the safety onus on drivers, saying conditions can change in an instant and motorists must be prepared to quickly make good decisions.
Federal transportation agencies have never issued guidelines on when to close roads due to fog, fires and dust storms. National groups representing insurance companies, the Federal Highway Administration, the National Highway Transportation Safety Administration and the National Transportation Safety Board all said they had not heard of such a policy. The NTSB is investigating the Gainesville crash.
Florida is vulnerable to smoky roads since it has one of the nation's most active prescribed fire programs. It has a 16-item checklist for "smoke/fog incidents" that is part of a larger 28-page policy manual for Florida Highway Patrol shift commanders.
Closing a road, which can be costly for tractor-trailers shipping goods, is decided by a supervisor who consults with troopers at the scene, although any patrolman can make the call if there is imminent danger, said Capt. Mark Brown, chief of the patrol's media relations. In the I-75 pileup, a district lieutenant based in Gainesville who was the supervisor at the scene made the decision. A day earlier, a different spokesman said a sergeant and lieutenant determined after about three hours that conditions had cleared enough for drivers.
"We rely on the members on the ground, and their physical presence, people who are actually there — their feedback. The person that can actually see what is going on," Brown said.
Troopers also use information and forecasts from the National Weather Service. One key piece of information is an index estimating the humidity and smoke dispersion on a scale of 1 to 10. If the score is 7 or higher, the road should be closed.