All I heard was it was SOP from the test runs to do
something with the air just as the head end is passing under the southern most exit ramp at Dupont (there's another bridge they pass under down the track, going to the golf course) which was supposed to put the train in the right speed for that curve.
I'd heard an engineer friend say the term, "dump the air" to describe this, but maybe he didn't use the right term? Just repeating what I'd heard from the pros familiar with the line and how the test runs were conducted.
I've been an artist and a solider, but never a RR employee so I don't profess to be an expert in that field.
As I know the engineer from this crash, I sincerely hope he did what he'd been told. I understand that the test runs were
not conducted in wet weather conditions, though, which might have made a difference, but I don't know about that, either.
-Lee
Flickr photo set of my On30 layout