If you put the brakes in Emergency doesn't that automatically cut the engine to idle as well as releasing any independent (which shouldn't be working in push mode anyway) or dynamic brakes? If so, then there's no blended braking in Emergency - just train air. IMO that might be an issue in push mode: perhaps you *do* want the pushing locomotive to provide some extra braking perhaps with the dynamics to stretch the train a bit, relieving some of the effect of having 1/2 the train's weight back there? Of course, once things come off the track none of that really matters ...

Some Metrolink flack (Press relations person) said it takes 1/4-1/2 mile to stop the train from 79. That seems like a pretty wide range for emergency braking where everybody's just along for the ride. I'd guess that it's closer to 1/4 mile, assuming that the engineer (yes, the papers and TV insist on calling that person the "conductor") hit Emergency near the whistle post, given how close the locomotive ended up to the crossing. Track there is straight and level, possibly very slightly downgrade eastbound, if I read my Google terrain view correctly.

I also would like to see more on the effect of the large opening under the cab car, and what happened with the coupler. I'm sure NTSB will look at that. LA may not get snow (at normal Metrolink elevations anyway), but plows can be useful for deflecting other things too. As far as CEM "working as intended" - I think that hasn't gone to the jury yet, though those horribly uncomfortable super-high-back seats that are part of the package might in fact have helped by limiting how much some people could move during the stop and overturn. Finally, the Bombardier car apparently was a "bicycle car" where most of the lower level seats have been removed for bike racks; supposedly, CEM retrofits were not done to them, though on a recent LA trip I did see the nasty seats on at least some of the older cars.