Usually the truck bypass lanes are there for several reasons. They get the big trucks out of the way of the smaller vehicles, they bypass a low or lower overpass, they offer a gentler slope to the grade and/or they allow a truck to exit and merge while still in the right hand lane...especially handy if there's another freeway merging, such as the grade coming out of LA where I-5 meets Hwy 14 to the high desert.
In California, anyone can use them and the truckers aren't required to do so but please use caution...I've seen cars do stupid things trying to beat the trucks etc......Dennis
