Left Lane Hogs
Keep Right Except to Pass - More than just a courteous gesture, it is a basic rule of the road. How can freeways and highways operate efficiently when everyone decides to get into the left lane to pass one semi truck. How is it efficient when semi-trucks line up in the middle lane forcing other vehicles to pass on the left wen the right lane goes largely unused. That's not efficient. No wonder we don't have freedom of movement on the freeways, This is congestion that is created by bad driving habits, pure and simple. A little courtesy and respect on the road can go a long way toward reducing travel times, improving flow and reducing congestion, slowdowns, backups and the accidents they cause. We need to move to the right. Some states have taken a more proactive approach to this such as Mississippi which has signs posted everywhere stating "STATE LAW" "Slower Traffic Keep Right" other states have "Keep Right Except to Pass" posted along their multi-lane highways. The truth is something has to change.
Efficiency and Lane Use
When using the freeway or any multilane highway it operates most efficiently when vehicles are keeping to the rightmost lane possible and moving left when necessary to pass other traffic or when traffic patterns dicate to do so.
Keep Right Laws and Restrictions
Keep Right Except to Pass
By far the most restrictive rule is Keep Right Except to Pass which means that vehicles are typically not allowed in the left lane unless they are passing a vehicle, upon completion of the pass, they must return to the right lane as soon as it is safe to do so. The left lane is to be kept clear for passing vehicles.
Slower Traffic Keep Right
A lesser restrictive rule is Slower Traffic Keep Right which means that slower moving vehicles are generally required to move or keep to the right lanes. While vehicles are allowed to use the left lane they are required to move to the right for faster moving vehicles to allow them to pass when it is safe to do so. In this case again the idea is that the left lane is to be kept clear for passing vehicles.
Right to Pass
This is a less restrictive law similar to the Slower Traffic Keep Right law that requires vehicles in the left lane to yield by moving to the right and allow faster vehicles behind to pass. States like Indiana have laws such as these. In other words vehicles are allowed to use any lane however are required to move right to yield to vehicles who want to pass and are not allowed to prevent other vehicles from passing.
Truck and Trailer Lane restrictions
Some states have lane restrictions such as vehicles with trailers and commercial trucks (semi or tractor-trailers) use the right or right two lanes of the freeway or interstate. Others will post restrictions allowing use of a particular lane that isnt normally allowed for use by trucks. There are also some states that prevent trucks from using the left lane at any time when there are 3 or more lanes travelling in one direction.
Truck and Trailer Speed Limits
Many states have statutory speeds that are set 5 to 10 MPH slower for trucks and trailers than passenger vehicle speeds. In California, trucks and vehicles with trailers are limited to 55 MPH regardless of the passenger vehicle posted speed.