The truck routes along the 5 are exactly the sorts of bypasses I mentioned -- they avoid a lot of the tricky high speed merging. Very useful!
And the term "the grapevine" was originally applied to the old highway that led from LA to Bakersfield -- it was very twisty, like an old grapevine. The area is still known by that name, even though Interstate 5 is much straighter. There is a town known as Grapevine at the south end of the San Joaquin, but I think that the town (really just a truck stop and a shopping center) was named after the highway.
The grades up from Castaic (northbound) and south from Grapevine are still pretty significant hills. My old Pathfinder could not tow my trailer more than 50 mph up the hill -- my new Tacoma can hold it at 60.
