The Loudoun County (Va.) School Board has voted to require seat belts on all new buses. Board members say they want to reinforce the buckle-up habit that children learn in family vehicles and set a higher safety standard in a county with intensifying congestion and many unpaved roads. Studies have shown that large buses with high, padded seats are safer than the average family car, even without seat belts. Adding seat belts to buses poses cost and design questions, and for those reasons, most large, standard-size school buses don't have them. Last year, the U.S. transportation department proposed safety standards that would require small school buses -- those weighing less than 10,000 pounds -- to be equipped with lap-and-shoulder belts; current rules for those buses call for lap belts only.