Superelevation

[alloboard]

Can a superelevated curve be located at a railroad grade crossing? If so whow can that be built and how will it look. How will cars be able to drive across superelevated grade crossing? I want to build it on my HO scale train layout

[RME]

alloboard

Can a superelevated curve be located at a railroad grade crossing? If so whow can that be built and how will it look. How will cars be able to drive across superelevated grade crossing? I want to build it on my HO scale train layout

Here's one reference, of many, that discusses the issue.

As noted, the immediate issue is that the different rail heights, spaced a fixed distance apart, impose a high shock load on road vehicles exceeding a certain speed.  This is made more difficult if the road falls away following the profile of the ballast prism on the high side, particularly with respect to high-centering or trucks with long overhang..

To get around this, you'd want to have a relatively long dip on the low side, vertical-transition-spiraled in and out, and then a modified-trapezoid hump up and over from the high rail to the continuation of the road (think of it as the inverse double transition spiral from the dip).  A certain amount of vertical curvature can be carried in the paving units (whether cement, rubber, or wood) between the rails.  For high superelevation and high road speed, the hump might be dramatically large and extend over a considerable ground distance, possibly even including culvert or bridgework structure.

If you have multiple tracks the situation is more complicated.  You might have to put up strict speed-restriction signs (similar to speed-bump signs, showing the expected profile to be encountered), perhaps with flashing yellow alert lights.

Note that the force on the high rail when a car or truck crosses low-to-high can be substantial, and in a direction that might tend to loosen spikes in an area that can't be easily seen without pulling crossing panels.  So some passive measure to enforce lower speed, like having the crossing follow an S-turn over the crossing, might be advisable (I tend to disagree, though, with anything that makes a driver concentrate on steering when they ought to be keeping a lookout, or that makes an inattentive driver wind up somewhere off the road but on the tracks.)

For some reason I seem to remember that a road crossing near Ho-Ho-Kus, NJ went over the EL commuter tracks somewhere along a long superelevated curve, and that there was something like a 10mph speed limit over it.  This might be an example for you to follow.

[CShaveRR]

Get yourself a street view of 450 South Main Street, Glen Ellyn, Illinois (which, by the way, is a great place to take your kids and/or train-lovers!), and look due south.

This is where Main Street crosses the three-track main line of the Union Pacific (ex C&NW) on a definite curve.  There is superelevation here, but the grade of the street seems to accommodate it quite well.  I've never heard of any mishaps related to the design of this crossing.

[alloboard]

Thanks allot for your time and effort replying to this topic. Can you find fout more info about that grade crossing that you're talking about? While Iconduct my own investigation.

[alloboard]

Thanks for the illustrative reference.

[alloboard]

I used KATO Superelevated 28in radius curve on a ralroad crossing in my HO scale layout. I will imply the roadway method. I have Faller HO cars that will run through this railroad crossing.

[mudchicken]

Highway grade must accomodate the grade and profile of the rails.

The street grade is "molded" to the top of rail / cross level track grade. No vertical curves for the pavement while crossing the tracks. 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. (otherwise it never rides correctly for the rubber tired vehicles or trains....the trucks and car impact loading on the crossing planks will accelerate the destruction of an already rough crossing)

Amazing how often the highway bubbas try the reverse, with disastrous results.

 

[rcdrye]

At one time Gary Railways had a crossing with the South Shore Line's double track superelvated main line near the now-closed Ambridge station.  Quite a ride for the streetcars.

[timz]

As I recall circa 1970 SFe had 5 inches superelevation at this grade xing (two road lanes then)

https://goo.gl/maps/MUj7erj3PZH2

Dunno what it has now.

[traisessive1]

Where I grew up there is a crossing built on a curve. Crews were always working on this crossing. 

The crossing was well marked for 40 k/ph but it still didn't deter motorists from either taking flight or going mining, depending on direction of travel. 

[RME]

timz

Dunno what it has now.

Here it is in street view.

[BaltACD]

RME

 

timz

Dunno what it has now. 

Here it is in street view.

Very little superelevation in evidence and the street profile seems to account for what superelevation there is.

[BaltACD]

Sykesville, MD on CSX's Old Main Line - fortunately there are S curves on either side of the crossing to hold speeds down.  Crossing had been 'relatively' flat until a tie and surfacing gang came through a couple of years ago - renewed the crossing and put the superelevation back into the curve.

https://www.google.com/maps/place/Sykesville,+MD+21784/@39.3639966  ,-76.9689166,3a,60y,297.27h,64.16t/data=!3m6!1e1!3m4!1sAVoBbefEN8rbmXO78g38CA!2e0!7i13312!8i6656!4m5!3m4!1s0x89c825a803d10e75:0x8485decf2c9e21dc!8m2!3d39.3737149  !4d-76.9677566!6m1!1e1

[alloboard]

Why were they always working on the crossing?

[RME]

alloboard

Why were they always working on the crossing?

Read what MC said earlier.  The constant slamming of vehicle wheels, including heavy truck wheels, into the high rail in particular would be damaging the track alignment in the crossing.

[CSSHEGEWISCH]

The curve on the CWI main line at 130th Street where it ducked under the South Shore was superelevated until some time after the "Lake Cities" was discontinued in 1970.  The tracks were at the same level but not in the same plane so the grade crossing at 130th Street was a slow-speed crossing for auto traffic.

[timz]

The SFe curve

https://www.google.com/maps/@37.9963864,-122.3480728,124m/data=!3m1!1e3

is a 3-deg-- think the freight speed limit now is 45 mph, so probably 3 or 3-1/2 inches superelevation. The 1966 chart shows 5-1/2 inches-- passenger speed limit was 50.

(Obvious question: why so much superelev for a 50-mph 3-deg curve? No idea-- but the next curve to the southwest is more than 5 deg, and it too was 50 mph then, with 6 inch superelev.)

[BaltACD]

timz

The SFe curve

https://www.google.com/maps/@37.9963864,-122.3480728,124m/data=!3m1!1e3

is a 3-deg-- think the freight speed limit now is 45 mph, so probably 3 or 3-1/2 inches superelevation. The 1966 chart shows 5-1/2 inches-- passenger speed limit was 50.

(Obvious question: why so much superelev for a 50-mph 3-deg curve? No idea-- but the next curve to the southwest is more than 5 deg, and it too was 50 mph then, with 6 inch superelev.)

Looks like it is adjacent to a BNSF Intermodal facility!

Superelevation works to increase the 'overturning' speed of high center of gravity equipment, like rail cars and locomotives.  To a point, the more superelevation you build into a curve the higher speed it is safe to operate around that curve.  The operational drawback of with high levels of superelevation is that trains that are moving slower than the 'equlibrium' speed will then apply their forces against the bottom rail, and wearing it sooner than if more movement were operating at the equlibrium speed or faster.  The proper amount of superelevation is a juggling act between higher passenger train speeds and slower freight train speeds.

With superelevation being taken out of curves, it tells you that the operation of freight trains has become the winner. 

[Deggesty]

Back in '78, I rode the Floridian from Birmingham to Chicago; this was when the train used the former Monon between Louisville and Chicago. After we left Louisville, I was talking with the flagman, and commented that we could not run as fast as the Monon passenger trains ran because the L&N had reduced the superelevation on the curves.

 

[alloboard]

     People, its amazing how many new stuff about railroads one might question that you would say is it even possible?, does this or that exist that actually exists. i.e "superelevated railroad crossings."

[alloboard]

Very interesting.

[alloboard]

     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.

[Paul_D_North_Jr]

RME

alloboard

Can a superelevated curve be located at a railroad grade crossing? If so whow can that be built and how will it look. How will cars be able to drive across superelevated grade crossing? I want to build it on my HO scale train layout

Here's one reference, of many, that discusses the issue.

[snipped - PDN] 

Fig. 12 on pg. 14 of that reference -

https://books.google.com/books?id=hvvIgaGbGEQC&pg=PA21&lpg=PA21&dq=superelevated+grade+crossing&source=bl&ots=woOuHiTdsJ&sig=CD_3HS6sZgg1Ke_f6J52A8TL0cA&hl=en&sa=X&ved=0ahUKEwjQtI-048fQAhWEJCYKHTXaA98Q6AEIKjAD#v=onepage&q=superelevated%20grade%20crossing&f=false 

- 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 2-track Norfolk Southern Reading Line on a curve in Emmaus, PA at these Lat. / Long. coords.: N 40 32.906' W 75 29.331'

The situation is further 'flavored' by the adjoining crossing of the single-track East Penn RR's ( http://www.eastpennrr.com/ ) Perkiomen Line a few feet to the east.   

Much the same happens when a local road intersects a high-speed road in a super-elevated curve.

- Paul North.

[RME]

Paul_D_North_Jr

(though dimensioning such things in mm is silly).

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.

[Norm48327]

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

[tree68]

Norm48327

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!

[CMStPnP]

alloboard

Can a superelevated curve be located at a railroad grade crossing? If so whow can that be built and how will it look. How will cars be able to drive across superelevated grade crossing? I want to build it on my HO scale train layout

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.

[alloboard]

Thanks

[alloboard]

     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?

[Norm48327]

tree68

Norm48327

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!

I have to clarify. The road is straight. The track is a 2 degree curve.