JEFFERSON CITY - A new law goes into effect today banning trucks registered for a gross weight of 48,000 pounds or more from using the far left-hand lane when traveling on interstate highways, freeways or expressways in urban areas that have three or more lanes traveling in the same direction.

So far, this restriction only applies to certain roadways in the St. Louis and Kansas City metropolitan areas.

This restriction will not apply when traffic is directed to use a lane other than the right lane or if the right lane is closed to traffic while under construction or repair. There will also be exceptions when a truck needs to make a left-hand exit.

MoDOT is currently producing signs to mark restricted areas and will begin installing them by mid-September. Prior to that, MoDOT's Motor Carrier Services Division has already taken steps to inform the state's trucking industry. MoDOT will also use its electronic message boards to notify drivers in the affected areas.