A lobbying group for America's largest trucking companies is trying to put the breaks on big rigs.
The group wants the makers of semi-trucks to install devices that limit truckers' speeds. The American Trucking Association said if speeds were limited to 68 mph, it would reduce highway crashes.
Many large trucking companies already have devices installed to limit drivers' speeds below 68 mph. The consumer group "Public Citizen" said an even more effective way to improve driver safety is to pay drivers by the hour rather than by the mile.