Very interesting.
I wonder how many model railroaders implement superelelevation in their layouts. Sadly I have a feeling that this technical structure might be easily overlooked or simply omitted in the name of forgetting. It almost happed to me I overlooked this at first but I soon realized this without it being too late. 90% of the curves are superelevated in my HO scale layout.
Fig. 12 on pg. 14 of that reference -
- illustrates the 3" / 6" at 30’ away principle that MC mentions above (though dimensioning such things in mm is silly).
My personal favorite is the E. Harrison St. crossing of the
Not as silly as it appears to common sense; it’s mandated by the SI deprecation rules (unless you want to go to mks and measure everything in decimal meters, even more worthless)
Unlike the more sensible English decimal-inch measurement for this kind of thing, specifying mm does not imply precision to mm scale; it only reflects the powers-of-three grouping with meter as the base unit that has made the decimeter (the only real haptic unit of the bunch) fully deprecated and the centimeter (despite the wack precedent of the Gray vs. Sievert) officially frowned upon.
I haven’t figured out the European conventions for actually notating precision and tolerance when this silly mm-for-everything convention is in use for large-scale situations. They’re just too arcane and user-hostile. And the American conventions (setting defaults for classes of drawing, or specifying explicit plus/minus allowance in decimal units) are just too sensible by comparison.
Here’s one I cross regularly. One way it’s a launch ramp and the other way it’s a dive into the hill. Any speed over thirty is abusing the suspension on your car.
42°43’53.83"N 83°29’50.87"W
And that’s not even on a curve!
THere is actually a working example on the Seminole Gulf Railway in Fort Meyer’s Florida. I forget what street crossing though…you can probably spot it on a map.
Thanks
I noticed in Rahway Station NJ there seems to be superelevation on straight track on the express commuter the second inner tracks on the 6 lane roadway, both north and south bound. I noticed the express diesels from Hoboken on the second inner tracks tilt whenever I’m waiting for a train when I’m on the northbound or southbound platforms. Why is that?
I have to clarify. The road is straight. The track is a 2 degree curve.
Better get my eyeballs recalibrated - in the satellite image the track looks straight as an arrow.
LOL I told you so. [:D]
Track chart says 2 degrees. Look GE in street view.
I presume you mean Gray versus RAD (or Sievert vs REM). Difference between Gray/Sievert and RAD/REM is a “quality factor” wrt biological damage versus absorbed energy (e.g. neutrons cause a lot more damage for a given absorbed dose than gamma photons). I mentally convert Sieverts to REM…
I also prefer explicit versus implicit tolerances. An example of where things can go wrong with mm, I remember a rant complaining about dealing with US letter versus A4 paper sizes, with letter size was given as 216 by 279mm, where exact size is 215.9 by 279.4mm (the 0.4mm difference will be noticeable). The ironic aspect of the rant is that specifying size to 0.1mm gives an exact size for US letter but an approximation to A4…
I think you guys are looking at the wrong crossing. Andersonville Rd crosses the Holly sub three times. The crossing you should be looking at is just south of Farley Rd. It is in either the 8000 or 9000 block of Andersonville.
I C&P’d the lat/lon you posted. The spot you’re talking about is at N 42 42’ 48" W 83 28’ 30".
And that one is definitely on a curve…
Actually, I didn’t mean “vs.” at all; I was really saying ‘Gray AND Sievert’ (as examples of a rampantly non-SI conversion from RAD and REM respectively). Both are defined in the same units (joule/kg in MKS) and the small dose is quantized following usual conventions as ‘milligray’ and ‘millisievert’ – at which point if you are converting from RAD or REM there is a very real possibility of missing a decimal place in the double conversion. Now, it’s easy to figure out why they did the definition as 2 decimal places (it gets you to Nice Round Numbers as a basis, a RAD for example being 0.01j/kg so a ‘base unit’ with a nice integer in the numerator is 100x; a ‘sensible’ power-of-3 counterpart would be why we use nm for wavelength instead of Angstrom units). But is having a nice round number for a definition worth the conversion errors?
No reason straight track would be designed with superelevation. Is track 1 actually straight thru Rahway?
But track 4 might be straight, so we assume you’re wrong about that track being superelevated.
We need to see clear pictures of this, preferably with some sort of clinometer or ‘plumb’ reference in the frame to establish true perpendicular.
I can think offhand of no ‘engineering’ reason to superelevate rail in straight track UNLESS the two rails are different section (as, it appeared, happened many places on the PRR in the immediate postwar period!) And even then, I’d expect the purpose of ‘tilt’ in the track would be to keep the two railhead contact areas substantially cross-level.
Leads me to wonder if there is subsidence of some kind, or an error in grading, although it’s hard to believe such a thing would occur on the NEC in Rahway. Photos will document the situation (or the optical illusion or whatever that might be the ‘null hypothesis’ of sorts for this observation).
I agree with you.