The Grapevine sits at an elevation of 4,160 feet and represents the highest point on I-5 in California. It’s a critical freight corridor for trucks hauling cargo from the ports in Oakland, Los Angeles, and Long Beach. The northbound descent from Tejon Summit drops 2,613 feet over 11.6 miles, with the steepest section — the Grapevine Hill — running about 6% grade for 5 miles.
If you ever go through it, you will see plenty of semi trucks in the right lane slowly climbing the hill while getting passed by lighter vehicles.
McLelland described the challenge in both directions. Running northbound with a loaded trailer, losing momentum on a steep grade means speed drops fast and recovering is difficult. Running southbound requires constant attention to braking and heat management — though as McLelland pointed out, “that isn’t a problem for an EV when you’ve got regenerative braking doing most of the work.”
That last point is significant. Regenerative braking on steep descents is one of the Tesla Semi’s structural advantages over diesel, the truck recovers energy instead of burning through brake pads, and there’s no risk of brake fade on long downhill stretches. For a fleet operator running the Grapevine regularly, that’s a real operational benefit.
This assumes that the battery has the capacity to accept the power generated. It can’t put it anywhere if it is already at 100%. This shouldn’t be a problem as it can be planned for in the system.
I mentioned in another thread that the Orinoco Mining diesel-electric ore trains in Venezuela used regenerative breaking but, not having batteries, they used resistance coils to use up the juice. The semis would have this problem only if fully charged at the top of a hill. Should be an easy problem to solve with route planning.
I commend any vehicle able to use their regenerative braking rather than melt away their brake pads.
However, praising a semi because of its ability to go up and down a 6% grade is hardly any significant accomplishment otherwise. When making efforts to minimize grades – both steepness and duration, freeways were supposedly limited to 6% unless mitigating safety measures were also added. My guess is many here have driven one or more stretch of a freeway with grades of 7% or more and/or stretches where runaway truck exits/ramps were added. Many non-interstate highways have such steep stretches too.
I drive a lot in Colorado. Many roads off interstate are greater than 6% as well as certain stretches of the interstate.
