When dad was a teen in the 30s he worked for a lumber yard in Alhambra. He would occasionally hauls a load of lumber to Bakersfield on the original grapevine road that traversed the very tops of the mountain range. They had a solid-tired Mack truck and the trip took a whole day. Dad's job was to walk ahead of the truck and warn traffic coming the other way that there was a big truck coming (very slowly!) around the bend.