When roads are unsafe because of weather or other elements making for adverse driving conditions -- such as fog, smoke, wind, dust or ice -- local officials in Kentucky and other states are usually left with the difficult decision of when to close a busy roadway in order to prevent car accidents.

Recent news of a massive pileup of vehicles on Florida Interstate 75 in Gainesville that left 11 dead has left many people wondering why state and federal guidelines do not exist for interstate and road closures. Typically the decision is left to local transportation officials or highway patrol troopers who must make the judgment on what they see for themselves.

Many states are prone to inclement conditions and suddenly changing weather. Maine has smoke breakouts, for example, owing to the state's heavily wooded areas. Arizona has a special problem with dust that blocks visibility on highways.

In many states, including Kentucky, fog is a dangerous condition that can occur in an instant. A chain collision similar to the one in Florida also recently occurred in New Orleans. The Florida roadway was closed because of smoke, but was reopened by troopers a short time later. Officials are wondering whether that was a wise decision. The National Transportation Safety Board is investigating the accident.

some locales use information and forecasts taken from the National Weather Service (NWS) and rely on that agency's Low Visibility Occurrence Risk Index. That index estimates humidity and smoke, ranking it on a one to 10 scale. The NWS states that conditions rated a six at the scene of the recent Florida crash.

Source: CBS News, "Few guidelines exist on when to shut down roads" Feb. 1, 2012