On the weekend of July 15-16, a ten mile stretch of one of heaviest travelled sections of the Los Angeles freeway system, the 405 between the 101 and the 10, will be closed for repairs. This section routinely handles over 218,000 cars a day and goes over Sepulveda Pass from the Westside into the San Fernando Valley (AKA the Valley.)
The intersection of the 101 and the 405 is usually the busiest freeway intersection in the US, which gives an idea of the traffic volume. Among the construction planned is the dismantling of half of a bridge, all of which authorities promise will be done on time for re-opening by rush hour Monday morning. We shall see.
Sepulveda Blvd is the only nearly alternative route through the pass and will no doubt become a twenty mile long parking lot. There are a few canyon routes nearby but they are twisty and narrow. The closure will dump massive traffic onto the 101, which winds from the Valley through Hollywood to downtown, and it too will become impassable (or more impassable than usual.) Worse. Los Angeles airport is about eight miles south of the southern end of the closure, so anyone going or coming from there will be forced to find alternate routes. Good luck with that. In short, the entire L.A. freeway system will be impacted.
I used to live on the Westside and also in the Valley. That stretch of the 405 can be hellish on a good day. Carmageddon weekend looks to be apocalytic. I implore you! Do not go to L.A. of the weekend of July 16-17 if you can possibly avoid it.