Nudge --
Yes, there are still operators on every BART train, and these BART
train operators actually do operate the trains when necessary.

Folks, [lease correct me if I am wrong about this next part --
On the BART system, "Road Manual" is 25 mph maximum and
"Yard Manual" is 10 mph maximum.
The operator is the initial Incident Commander in an emergency.

Rasputin ---
Thank you VERY much for that fascinating information
about polymerization of air pollutants on the rail head.
Learn something new every day!

mook --
From what I have read, SMART is required to maintain
"temporal separation" between all freight train movements
and all passenger train movements. This is currently done in
San Diego with the San Diego Trolleys. So -- there will be no
conflicts between SMART trains and freight trains.

To all ---
In all conflicts -- and how to make SMART safe enough is a conflict --
there are 3 things:
1. What you want,
2. What you really need, and
3. Your favorite solution.
PTC -- in any form -- is a favorite solution.
Is SMART using any form of the ACSES* system currently in use in the NEC?
(*"ACSES" means "Advanced Civil Speed Enforcement System".)
I am pretty sure from what I have read that SMART is not using an ACSES
system, but I had to ask.

IMO, the money being spent on PTC would be much better spent doing
something really effective about drunk and stupid drivers. The carnage
on our roads is far, far worse than any train wreck, in terms of the
sheer number of people injured and killed every single day.