Metrolink is a transit operation. There was only one person in the cab, almost certainly. Even Amtrak operates with only the engineer in the cab for some corridor runs - there's a mileage or time threshold below which it's a "commuter" operation for crew purposes.

The train ran a red. Why - that's what investigation is for. If the signal was red and the switch was aligned against Metrolink, why didn't it derail at the switch? That's what investigation is for. When it's all done, the finding will probably be along the lines of: Metrolink ran a red and hit the freight train approaching in the block. Why will include a whole list of things ranked in some way based on probability and/or evidence. Rules and other procedures will probably (hopefully) be changed as a result - this kind of thing should never happen, and rules and procedures are there to prevent what's physically possible but should never happen. Maybe Metrolink will invest in a few ATS setups, especially at entrances to single track, assuming that the lawsuits don't put them out of business? Is there a signal at departure from the Chatsworth platform that might provide warning that something has changed since entering the siding - if not should there be, and what's the implication and cost of that for other locations?

As far as the car damage is concerned, the relatively lightweight Metrolink train hit essentially an immovable object at about 40 mph based on news stories, in fact one that was fighting back (moving at least 20 mph or so downhill with lots of mass behind it, so closing speed of something near 60 mph). If news stories are right that some front-end crew members from both trains survived, some kind of miracle occurred. Basic laws of physics: Metrolink train immediately reversed on impact, and the stresses were too much for virtually any practical passenger car to withstand. To some extent the coke can analogy used for train vs. auto also works for freight train vs. commuter train. Given the level of damage in this and other LA wrecks, though, I can't help wondering if there's some structural and stability issue with the GO-Transit/Bombardier design. I haven't heard of such severe damage with the more typical cars like Cal Cars or full-double-deck commute cars like Caltrain's old ones (similar to many in Chicago), though of course the local versions (Cal Cars and Caltrain) haven't been "tested" in the kind of wreck this was. There certainly have been some major wrecks in the Chicago area with similar equipment, though perhaps not as massively head-on as this one; how did the equipment perform there and are there lessons to learn?

The main lessons I see in this for SMART are: training and enforcement of rules; ditto; ditto; ditto; get a GOOD signal system (with ATS even if only selectively applied at key spots) and maintain it; and get MUs that meet mainline railroad structural standards (not light rail) for the times when it all comes unglued anyway (I'm a firm believer in Murphy's Law as applied to railroads and most other complex situations). NWP freight operations will not, in the long term assuming enough traffic for economic survival, be able to live with a time-separated operation that allows use of light rail passenger equipment. On the plus side regarding ATS, it's unlikely that NWP will have so many locomotives that it would be financially infeasible to install it (one of the major arguments by BNSF after the Placentia crash), and for the SMART vehicles it's a matter (at some price) of checking an option box when ordering.