Friday, June 22, 2012

FRA weight penalties: Electric boogaloo

A significant part of the reason why I've used foreign rolling stock accelerations in some of my previous posts is that, with the exception of Colorado Railcar and typical diesel push-pull from one MBTA document, I simply haven't had any data on American FRA-compliant rolling stock to work with. Luckily, that's changed a bit as I've finally tracked down a document which has simulated data for  Metro North's M3a and M7 EMUs (page 16). Unfortunately it's hosted on what looks to be the Chinese equivalent of Scribd, so actually getting the PDF isn't terribly feasible, though it can be read online.

Looking at the chart, without ampere limits, an M7 takes about 65-70 seconds to reach 60mph, 110-115 to reach 80mph, and reaches 90mph at some time after 160 seconds. An older M3a takes ~78 and 130-135 seconds for 60 and 80 miles per hour. Interestingly, that is actually worse than a Bombardier Talent DMU. In fact, if you watch the cab ride video of the Class 222 accelerating linked in the comment on that video, that vehicle achieves 60mph faster as well, looking to achieve that speed around the 58 second mark on the video, but only starting to move around 13-14 seconds in to the video, for a 0-60mph time of about 44 seconds.

Now, that said, it could very well be the case that the M7 is simply a poor performer even by American standards. Videos at this blog post comparing the M8 and Silverliner V show the latter achieving  60mph in 35 seconds, a very respectable figure in line with rest of the world equipment, though, of course, this is done at a significantly higher weight and consequently energy consumption.

2 comments:

  1. I want to say that the M7 has limited power because of the capability of low-voltage third rail, but its power-to-weight ratio is actually higher than those of the M8 and Silverliner V because it's lighter. And its initial acceleration is terrible even though all axles are powered, which I can't explain.

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    1. Hmm, maybe they skimped on things like bearings...

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