Okay, but the I-5 doesn't bother with loops and tunnels. It just barrels right over the top of the mountains, including a 5-mile section of 6% grade according to the sign (https://www.crashforensics.com/tejonpass.cfm). Trucks struggle to crawl over the top at like 30 mph, with tires. It's not exactly a roller coaster hill to be overcome with inertia.