I-405 the San Diego Freeway, Sepulveda Pass from U.S. 101 Ventura Freeway past the I-10 Santa Monica Freeway to LAX, LA International Airport, worst LA freeway. That doesn't include the uncompleted section of the I-710 Long Beach Freeway from I-10 San Bernardino Freeway to CA 134/I-210 in Pasadena. Still people are so opposed to that highway in their back yards, NIMBY. CA 210 would not be a worst freeway, but one of the best freeways constructed in Los Angeles and San Bernardino County. The Foothill Freeway extension. I would believe that the only criteria existing for a worst freeway would be no other than the mid 1950s Interstate 5 - Santa Ana Freeway from I-605 to the Los Angeles/Orange County border, a six lane freeway that is reduced down from ten lanes at the boundary going NW out of Orange County, it really puts the squeeze on traffic.
Scott