Norm48327I 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.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
LOL I told you so.
Track chart says 2 degrees. Look GE in street view.
Norm
RME 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.
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 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.
Norm48327I think you guys are looking at the wrong crossing.
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...
erikemI presume you mean Gray versus RAD (or Sievert vs REM).
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?
alloboardRahway 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?
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.
alloboardI 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 ... 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?
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.
My bad; There is a hardly noticeable slight curve that I ofthen overlook.
RME alloboard 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).
alloboard
Can't speak to Amtrak practices. On my carrier we rarely change both rails at the same time on a segement of track (I don't know why). Back in the day the PRR used a lot of 152 pound (I think) rail. I don't know exactly what the section height of that rail is, but it is perceptably bigger than 136 lb and other rail sections.
Could Amtrak have changed out one rail through Rahway to a lighter weight rail than its adjacent rail. 152 lb on one rail, 136 lb on the other would give superelevation unless the tie plates were shimed to make the rail tops at the same level.
Never too old to have a happy childhood!
Woodbridge train station NJ is located on a superelevated curve.
BaltACD RME alloboard 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). Can't speak to Amtrak practices. On my carrier we rarely change both rails at the same time on a segement of track (I don't know why). Back in the day the PRR used a lot of 152 pound (I think) rail. I don't know exactly what the section height of that rail is, but it is perceptably bigger than 136 lb and other rail sections. Could Amtrak have changed out one rail through Rahway to a lighter weight rail than its adjacent rail. 152 lb on one rail, 136 lb on the other would give superelevation unless the tie plates were shimed to make the rail tops at the same level.
Yes, 152# rail is 11/16" higher than 136# rail. This information is found in a Rail Chart provided by TX Holdings, Inc. 152# rail is 8 inches high; 136# rail is 7 5/16" high.
Johnny
155 PS section - also 8" high - was more common for the PRR than the 152, but both have been long gone from the NEC for several decades now.
141 RE is 7-7/16 high, or only 2/16" = 1/8" higher than the 136 RE. 132 RE is 7-1/8" high, or 3/16" less than 136 RE. 115 RE is 6-5/8" high - though I seriously doubt Amtrak uses anything that light/ small in the NEC - but if so, is only 13/16" shorter than the 141 RE. Bottom line, the height of differing rail sections on each side from changeouts is likely less than 1/2" even if one of the rails is head-worn down pretty much,
- Paul North.
mudchicken[snipped - PDN] . . . Multiple tracks require all rail tops to fall in the same plane and must be level/ in the same plane, as the rails until the pavement gets 30+ feet out from the rail. . . .
Normally, each track will have its 'low' / inside rail at the same elevations opposite each other. So the cross-section will have a flattened saw-tooth profile - about +5% up across/ between the rails of either track (0.25 ft. / 5 ft. from C/L rail to C/L rail), and about -2.5% from the 'high'/ outer rail of the inner track to the 'low'/ inner rail of the outside track (0.25 ft. / 10 ft.). Obviously, the transition from whatever the road's approach grade might be - to +5% to -2.5% to +5% in about 20 ft. - and then to whatever the road's leaving grade might be, could lead to a very rough ride.
Now, suppose that the track elevations are adjusted so that the tops of all of the rails are in the same plane as MC points out - think of the concentric slope of the outside of a dinner plate, or the banking of a racetrack or even a multi-lane highway curve. Carrying the +5% cross-slope across the 10 ft. distance between the 'high'/ outer rail of the inner track to the 'low'/ inner rail of the outside track will add about 9" to the (absolute) elevation = 0.50 ft. (6 ") plus the 3" from the inside track, and then another 3" to the 'high'/ outer rail of the outside track, as compared to the 'low' / inner rail of the inside track.
But another unwanted effect is to introduce a hump and several vertical curves in the outside track. With all the rails in the same plane, the 'low' / inner rail of the outside curve must rise at the crossing 3" + 6" = 9" = 0.75 ft. above the elevation it would otherwise have. That might not be enough to affect train handling, but it is going to make life difficult on the surfacing gang. Even a moderate 0.5% grade wold have to be 150 ft. long PVI to PVI for that - on each side, plus perhaps a couple hundred feet for the vertical curves at each end to transition into and out of that higher level. From 1,000 to 2,000 ft. on each side of the crossing might be required, depending on the operating speed and change of grade rate.
Then hope that for that outer track within that distance, there's no close overhead clearance bridges or tunnels, or open-deck bridges where the bridge timber thicknesses/ heights or span elevations will have to be increased accordingly, etc.
Far better to avoid these nuisances to abominations ! (borrowed from John F. Unsworth, P.Eng. [CPR] in his 2010 book Design of Modern Steel Railway Bridges).
Long ago and far away, before Highland Avenue, in Augusta, was widened to four lanes, it was an at grade crossing at the then Georgia Railroad near the Gordon Highway, i crossing on a superelevated curve. Today, the four lanes are elevated over the tracks.Highland Avenue was uphill from the Gordon Highway to Daniel Field, but dropped several feet to conform with the level of the rails and then after a bottom, more climbing. I could not locate any photos of the crossing in a quick web search.33 27 15.26N 82 02 43.54W
Our community is FREE to join. To participate you must either login or register for an account.