Yes the CHP seems to get the investigations over with, or at least out of the way, more quickly than the locals. But when there are a lot of vehicles and fatalities involved the investigation will take a long time. That's life in the business.

Interesting that there have been a number of lengthy Amtrak delays recently because local law enforcement puts "a hold" on the tracks while investigating something. So there's a railroad application of the issue too.

The time I was on a Cap Corridor that got "keyed" (the scrape was quite visible, but not particularly deep) by a semi at a grade crossing, though, the police (sheriff) investigation and most clearance activities took barely an hour and a half. The longest wait (we got going after about 2 hours) was for a new crew, despite it being perhaps 45 minutes from Sacramento or an hour and change from Oakland. We did manage to delay an already late #4, another Cap Corridor, and a freight until the track and car inspectors were happy enough to let them go by on the other track.