• Rail Physics & Track Class Science Discussion

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

rovetherr thanks for the info.I remain perplexed however as to how track can be classed for various speeds. Is it really just visual? therefore subjective? I've looked at lots of track all over the eastern u.s. Can't tell if 10 or 20mph is appropriate just by looking. for example, 3 new ties per 40' retain guage with 286k cars at 10mph. Never ran anything on our private trackage above 10 mph so i'm not trying to posture as knowledgeable. But back to my original question. why doesn't pas run the oil trains at 20mph? ken patrick
  by MEC407
This goes back to the discussion about harmonic roll. The railroads don't like to operate in the 12 to 23 MPH range because that's when harmonic roll becomes the most problematic... so their options are 10 or 25. We can argue about whether tank cars are more or less susceptible to harmonic roll than other types of rolling stock, but neither this railroad nor any other railroad is going to push their luck, especially when hauling something like crude oil.
  by rovetherr
Here are the standards that we are governed by when determining track class. http://www.ecfr.gov/cgi-bin/text-idx?c= ... .8&idno=49

And here is a guide for FRA/State DOT Inspectors on how to properly inspect track for compliance with the above standards. http://www.hsdl.org/?view&did=15770

Any deviation from the TSS requires some sort of remedial action, either repair or slow order, or both depending on the nature of the defect. Any increase in MAS above the limit for the current track class (basically an increase in the track class) requires FRA approval, which comes from the type of inspection listed in the second document I posted. For the most part, MAS is usually set at the maximum allowed by the track class, unless the physical plant dictates a lower speed, such as a sharp curve, or an area with high traffic/bad sight distance or close clearances that would effect trains at speed.
roveterr; i scanned the material. I found it detailed except for the 'rolling inspections' criteria. can anyone believe someone in a track vehicle can adequately judge 4 parallel tracks? I don't believe visual inspections can judge whether a track is good for 20-30 mph? subjectivity leads to safety thoughts. as an inspector i have no incentive to increase speeds. ken patrick