Ouch! That hurt. The famous Grapevine grade on the north side of Tejon Pass in Southern California is legendary for its five miles of 6% grade, especially with truckers. It’s a pure test of horsepower going up, and of braking going down. Plenty of truckers found out the hard way that if going down in a gear or two too high, the consequences can be severe.
This Ford went over the side and spilled its load of new Falcons and a pickup. Note the “drip cloth” on the underside of the red Falcon; that’s how the cars on the lower deck were protected from the inevitable drips. And there’s an open suitcase on the far lower left side of the picture. Looks like it went flying out the passenger side door that opened up.
This is from 1947, some years after it was extensively widened, regraded and straightened in 1934. . We can only speculate how slow this truck is going. I remember flying past semis working their way up the Grapevine in the extra-slow truck lane, probably doing no more than about 15, maybe 20 mph. That was in the late 70s; this tanker is probably going half that fast.
Diesel engine (“Jake”) brakes and improved wheel brakes have made incidents much less common. Unless of course a winter snow storm hits. I remember sitting for four hours one winter, waiting for a jackknifed big rig to be cleared off the highway.