BATON ROUGE, La. (AP) — The Louisiana Highway Safety Commission has issued a warning to families planning road trips this summer: Slow down.

John LeBlanc, the commission's executive director, says speeding is a factor in about one-third of crash deaths in Louisiana. He says driving while intoxicated and not wearing seat belts also account for many of the traffic deaths and injuries both in Louisiana and across the nation.

A study conducted by the National Highway Traffic Safety Administration has found that roughly 668 people were killed in highway crashes in Louisiana last year, and 62 percent of those killed were not buckled up.

LeBlanc said Thursday the total cost of a speeding ticket and court fees in Louisiana can be more $100, especially for repeat offenses, which can also result in increased insurance premiums.