What speed would the train have reduced to in six seconds had the engineer made an emergency application when he became aware of the over speed-condition?

About 30 MPH could have been scrubbed off in 6 seconds. Assuming a coef. of friction of .25 (steel on steel) and a full 6 seconds of braking. That doesn't take into account reaction time, which can vary from 0.5-1.5 sec.

I think by overspeed, we're talking he was doing almost 82 when the absolute limit is 79, NOT the 30 MPH curve.

When the engineer commented that he was over-speed, I would assume he was not referring to being 2-3 mph over the speed limit of 79. I doubt that he would have commented about that. I assume he commented about his speed because he realized it would be impossible to reduce to the 30 mph before entering the 30 mph restriction.

What would you estimate to be the tip-over or derailing speed of that curve with train #501?

I would contend it's quite the opposite. While PTC/ATS wasn't active, that means the loco would of been locked into a 79 MPH restriction. I think he was beginning to push the speeds that would trigger a disciplinary action and/or a brake penalty application. (I've heard the exact numbers once, I can't remember the exact speed but it's pretty narrow) If he KNEW he was about to hit the 30 curve at 80, I would expected a big hole application. He might just of stayed on the rails had he done that. Probably would of been a VERY wild ride for a few seconds.

I see what you mean. He got into the situation of being unable to slow for the curve, apparently by forgetting about it or not realizing where he was. So he might have commented on speeding only in reference to being a couple mph over the limit while still being unaware of the problem with the curve just ahead.

If he wanted to get the speed down just a couple mph as quickly as possible, would an independent brake application be the best choice?

Something occurred to me while reading this: the author mentions that they were having trouble starting the new locomotive, which is what delayed departure 9 minutes. Think about that: in addition to running on a new line, the engineer was potentially operating a new locomotive with completely different controls for the first time. Ever been in a new car and struggled to find things like the windshield wipers while driving down the road? This guy was no doubt trying to figure out where everything was on the new unit, instead of reaching for it while keeping his eyes on the track as he would with a Genesis unit he had been in thousands of times. All this is a lot to throw at a guy who is probably under pressure to make up the lost time for the big shots on the train.

I can only tell you that the commuter trains I used to operate could go from 50-0 in the span of 1200' with a full service application and the use of blended brake. I've never tried 79-0, and my experience is with cars equipped with disc brakes on bi-levels. An emergency application on a passenger train stops it so much quicker than with freight, it's like the difference between driving a corvette and a loaded semi. My guess is that if he had "big-holed" it a full 6 seconds before he hit the curve, it might have stayed on the tracks. Only one man's opinion, but at least I can say I've had passenger experience.

I keep reading/hearing about the PTC extension and the explanation X number of people have died because of this. On the N&W email forum, I keep reading about more signals getting converted, the railroads complained they needed more time for the conversion. Plenty of territory needs to be done. Now people argue if PTC would have prevented this accident, if you have all the programming set properly to all the controls we say it would.
The other issue here is familiarity with the line and apparently the engine as it seems the engineer was dropped into the controls of a new engine he was perhaps unfamiliar with.
This reminds me of the accident NKP 767 had with a Wabash passenger train in New Haven, IN, the Wabash passenger train was approaching the crossing and apparently ran a red signal and 767 plowed into Wabash Passenger train. The investigation showed the Wabash crew was young and not that familiar with the route and Wabash had kinda rushed getting the train crewed. Far as I can tell, you can have PTC, but if you have an unfamiliar crew your going to have the 501 crash again. Everybody on the planet by now knows you have a too sharp curve here, make sure your crew knows it.

The mentality being espoused by those "Monday morning quarterbackers" and "drive-by media" (I'm not a Rush Limbaugh loyalist, but he has it right about his analysis of talking heads jetting to a story, having 30 minutes to be able to pass themselves off as an instant "expert," then jetting off to the next big story) is that PTC is supposed to automatically brake the train in advance of the curve if the engineer did not do so in advance--that was supposed to be the entire POINT of the multi-billion-dollar, largely-unfunded mandate.

I'll leave it to those who have studied the issues even further than I have in railroad-industry publications and publicity to confirm or berate that analysis.

Do you have any possible explanation for why the engineer chose to only make an application of the independent brake as he approached the curve?

The explanation given, that the engineer received an overspeed indication from the locomotive and was responding to it, is (at this point in time) the correct one.

For no more than a 2mph reduction, using the blended brake would be almost impossible to modulate - by the time the car brakes had set up and then released, you'd have taken off more than enough to keep you close to the track speed limit. Using the independent is a reasonable way to 'fine-tune' the speed.

Tacit in that, of course, is the presumption (which I think is glaringly correct) that the person in command, whether the nominal engineer or a 'trainee', had no idea about the impending curve. No attempt was made to actuate the train brake, apparently even up to the point the camera sees the crew reacting to the derailing locomotive's movement. That leaves open the question of the time of what was essentially a "desirable UDE", probably due to trainline separation -- fractional seconds on the event recorders becoming significant in analyzing the timing.

If someone could provide a link to the train-radio quote from the head end shortly after the accident, with the 'we were going around the corner' language in it, and a transcript, I'd appreciate it. The person seemed almost chipper about the 'incident' when I heard it in news coverage...

I don't think there was any transmission from the head end. The engineer smashed his face and the conductor in training had a broken leg (supposedly). All the site comms were from the assigned conductor.

That would make far better sense, and I suspect you are correct.