"When a big rig jack-knifed about 8:30 a.m. Thursday, Jan. 12, 2017, on Interstate 80 at the top of a grade above the Floriston, the California Highway Patrol was faced with a shut down of the freeway to wait for a tow truck. Instead, because the double-trailer Fed-Ex rig still had engine power, it was escorted by CHP cruisers, sideways at times, down the slope." Text accompanying that video.
North of the Los Angeles region, I-80 over Donner pass is the only all-weather route out of California to head toward the Eastern states. This is the route of the original Transcontinental railroad, there aren't better alternatives over the Sierras for hundreds of miles north or south of there. (yes Donner, named for the wagon train that couldn't get over that summit in unexpected early winter, starved in 25 feet of snow, resorted to cannibalism). Its harsh country.
Why drive on ice? Some FedEx dispatcher sent that guy out with doubles presumably to keep deliveries on schedule. I wonder if that second trailer was up to spec - good tires and chains, brakes equal to the other equipment. Poor equipment maintenance might explain why the rig jackknifed in the first place.