From: jishnu@nospam.verizon.net   
      
   On 5/20/2015 8:16 PM, Denis McMahon wrote:   
   > On Wed, 20 May 2015 16:54:42 -0400, Jishnu Mukerji wrote:   
   >   
   >> On 5/17/2015 9:56 AM, Denis McMahon wrote:   
   >>> On Sun, 17 May 2015 09:49:15 -0400, Jishnu Mukerji wrote:   
   >>>>   
   >>>> With the complete operationalization of ACSES all these civil speed   
   >>>> limits will appear on the ADU in the cab, and the specific speed limit   
   >>>> applies to that class of train is the one that will appear. There are   
   >>>> five different classes of trains on the NEC which have different speed   
   >>>> limits that apply to them.   
   >   
   >>> Are we still talking about the curve where the derailment happened?   
   >   
   >>> Tilt doesn't change the speed at which it's safe to take a curve, tilt   
   >>> just makes it less uncomfortable for the passengers at higher speeds.   
   >   
   >>> I doubt very much that anything would have been able to take that curve   
   >>> at 100 mph just by enabling tilt - it's (reportedly) 2900 feet radius   
   >>> and 5 inches of superelevation.   
   >   
   >> I don't think anyone has suggested that tilt would make it possible to   
   >> take that curve at 100mph. The speed limit for Class A trains on that   
   >> curve is 60mph, that is 10mph faster than Class B trains.   
   >   
   > Hence my confusion at the bit of your earlier comment that you snipped:   
   >   
   > "Those speed limits apply to so called Class B trains like the Amtrak   
   > Northeast Regionals and Acelas with tilt mechanism disabled. Class A   
   > trains (Acelas with tilt enabled) are allowed to go through that curve at   
   > 100mph."   
   >   
   > and seeking clarification as to whether we were still discussing the   
   > derailment curve.   
   >   
      
   That was an error. My bad. Sorry. It should have said 60mph. They are   
   allowed to go a little faster.   
      
   Oddly, many years back another Amtrak Engineer managed to run through   
   the Elizabeth curve at 100mph without derailing. The speed limit on that   
   curve is 55mph for Class B and I believe 65mph for Class A. There was   
   significant damage to both the track and the trucks, specially of the   
   engine, which was an AEM-7, and the carriages were Amfleet Is.   
      
   The result of that was the institution of code drop to 45 mph before the   
   curve from both sides forcing the train to enter the curve at 45mph.   
   There was a higher chance of someone making that error because the speed   
   limits on the straights on both sides of that curve is 100mph or more,   
   unlike the Frankford curve where eastbound it is 65mph to 80mph to 50mph   
   (curve) to 60mph (Ford Curve) to 110mph. In the reverse direction where   
   it is 110mph to 60mph, the forced speed drop was already in place.   
      
   --- SoupGate/W32 v1.03   
    * Origin: LiveWire BBS -=*=- UseNet FTN Gateway (1:2320/1)