Going from the Valley to OC (or vice versa)?
I have learned both from personal experience and from many friends and past listeners of my traffic reports…. For all intents and purposes, if you don’t need to go to or through the Los Angeles basin, from the Valley to Orange County, at all costs, avoid the 405 and the 5 freeways.
As a very general rule, the best way (and least trouble-prone) way to go from the San Fernando or Santa Clarita Valleys to Orange County is to take the 210 to the 57. Going from OC to the Valley can be a little trickier depending on the time of day, but again, usually 57 to 210 is the best route.
The 5 will be tempting because it is a “direct” route and is often cited as a first choice on map services like Google. The 405 can also be treated this way especially if you need to go to/from points in Northern OC like Seal Beach or Garden Grove.
The 405 on the West side can never be trusted – if there is a problem, there are many alternates but few good ones.
The 5 between Downtown LA and Anaheim/Buena Park is usually riddled with accidents and because it is laid out diagonally, it is very hard to find a direct alternate route. Stay safe and stick with the 210 and 57. Without traffic, this route will take between 90-120 minutes for most endpoints in the valley and Orange County. Generally add up to 45 minutes during peak traffic times, which is still FAR better than what you might risk anywhere on the 5 or 405 in LA county.