Collisions that grand are rare in the southern part of the state, but in the fall and winter months, several are likely to occur in the central valley. The tule fogs along the rivers can be astonishingly dense. I recall one fog I passed through near Bakersfield a number of years ago. When I say "near Bakersfield", I mean all of Bakersfield, and considerably more. It covered at least thirty miles of highway 99 in a blanket of varied densities, but visibility was never better than a couple of hundred feet. All along the way, there were banks of thicker fog, a few hundred feet wide, where visibility dropped to near zero. Still, the traffic sped along at 55 MPH. And this was at night!
People from other places are invariably amused, and frequently annoyed, by the fact that southern California drivers tend to slow down and become cautious grannies at the first sign of rain. They are flabbergasted when they discover the reckless abandon with which central California drivers speed through fogs so thick that cars thirty feet in front of them vanish altogether. They drive entirely on faith, and assume that nobody in front of them will stop, or even slow down enough to make a collision unavoidable. Sometimes their faith is not rewarded.
There is not one year in my memory in which there was not at least one spectacular pile-up on a central valley highway during the foggy season. It has almost become a fact of nature, like the summer brush fires, the winter floods, and the earthquakes. At least once a year, California drivers will pull the human, industrial age equivalent of a lemming-leap. The state has tried any number of things to diminish the carnage, from issuing fog warnings, to providing squads of Highway Patrol officers to lead convoys of cars and trucks through the foggiest stretches of highway, but nevertheless, we can count on tuning in the evening news and seeing the familiar scene of mangled wreckage strewn for several hundred yards along some highway near Stockton, or Modesto, or Fresno, or Bakersfield.
The night we spent more than half an hour rushing through the barely visible world along highway 99, with the taillights of the truck in front of us vanishing and reappearing every few seconds, was one of the longest nights I remember. About a dozen miles south of Bakersfield, the land rises toward the Tehachapi Mountains, and we began to emerge from the fog. It vanished completely by the time we reached the interchange with Interstate 5 at Grapevine, where the merged highways begin their steep run up the rugged canyon leading to Tejon Pass. The eight lanes of glittering taillights and headlights snaking along the canyon walls were one of the most welcome sights I had ever seen. I realized that my jaw was aching, from having had my teeth clenched for so long. Since that night, I have avoided travelling in the central valley during the foggy season, and I recommend that you do, too.