I have always liked the sound of wheels click-clacking at diamonds. I suppose that the speed limits at diamonds run the full gamut, but I am wondering if there are some in remote areas that can be crossed at top or near top speeds or if their very construction requires a slow down.
Northtowne
Depends on where it is at, but the UP slams across the one here at Eurka at track speed.
When the MOW guys do their job right, its just another section of track.
Crossing frogs are the weakest, most brittle thing in the track structure.
Flange Bearing frogs at a 90 Degree crossing would be the ticket (aka-“Sheep Jumps”)
The fact that you have to jump that flangeway gap is the source of impact is more than any frog can handle, even the manganese explosive hardened variety. Fastest crossing frog that I was around was 60 MPH with a full time welder and rlatively light tonnage on the 60 MPH side.
If speed is that much an issue, grade separate.
If you want crossing clatter, you haven’t lived until you experienced ex-DM&IR ore jimmies hitting the Soo Line diamond at the crossing-on-the-bridge at Deval at 35 or 40 m.p.h. (at least!).
Rochelle’s diamonds are at a fairly acute angle, calling for a reduction in speed to 35 m.p.h. For UP, that’s a reduction from a top speed of 70. Most freights aren’t allowed 70, but the 35-m.p.h. restriction still slows everything down.
Seems like we’re out replacing the Darby Diamond every two or three years. Track speed, 50 mph, over it.
Nick
In the late 50’s when the L&HR was the middle man between the NH and PRR with the TOFC train the JET out of Boston to Maybrook, NY to Phillipsburg, NJ to Chicago, was at the L&HR/DL&W Sussex Branch crossing at Andover Jct., NJ one night. Had to vacate the interlocking shack when the southbound crossed the diamond at better than 55 for fear of jumping the track…we were told that was nightly procedure for that train, all the others did 30!
Not sure what the speed is on the two-track main at Deshler (Joe K would know) but a hundred empty hoppers crossing the diamond at speed is not conducive to sleep, especially if you’re in a tent…
There are frogs for high-speed switches that feature movable rails set in accordance with the setting of the pair of points and that permit practically continuous support of the wheel rather than an interruption. Is there anything similar for diamond crossings? I am not sure I could figure out how to do it for a right-angle crossing, but an acute angle would be similar to a switch frog.
Kensington Junction has (had?) movable point frogs on some of the acute-angle crossings where the South Shore crosses the IC passenger and freight mains.
I believe that Western Avenue (where MILW crossed the former CNW main line, a couple of miles out of their Chicago terminals) has movable-point diamonds as well. Some of them, anyway–that’s four tracks crossing three there! I think the ones with the movable points at the diamonds are the same ones that have double-slip switches.
The MILW-EJ&E crossing at Roundout, IL had a special instruction back in the 40’s - ‘All Hiawatha trains will slow down to 100 mph crossing over the diamonds’…
Jim
What would be the purpose in any slowing? What deleterious effect would it be attempting to allay that actually speeding up wouldn’t also accomplish? I am trying to link this to the effect of improved handling and road comfort on gravel roads. At a certain speed, you had better leave it…the speed, I mean. You either lose 15 kph in a hurry to regain a measure of control/comfort or you increase your speed and find that you have accomplished the same thing.
-Crandell
I’d guess that even on a very well maintained diamond, there might be some ride issues on the approaches. Can’t be spilling that coffee! Would that we saw that kind of speed “restriction” today…
We’ve found that 85’ coaches, jointed rail, and 15 mph don’t mix well together. At that speed the cars seem to find a natural harmonic resulting in pronounced swaying. Just a few mph faster or slower and nobody even notices. At 30 mph, it rides almost as smoothly as CWR.
All to let ‘trolley cars’ to cross a Class I carrier.
The distance of the flange opening for the cross route creates a 1 to 2 inch (approx.) void. When rolling across the void the wheel will, because of gravity, drop into the void. As the wheel continues to roll it impacts the other side of the void, where it is again raised back up to rail level. On cars loaded to a normal 286K capacity, each wheel has the effect of a 36K hammer hitting the frog point on the far side of the void. I am not much with the engineering formulas, but take that 36K hammers force and multiply it by the speed and you have some SERIOUS SERIOUS forces being transmitted to the diamond frogs…with a 100 car train you are having over 400 of these hammering incidents on each frog with the passage of the train…train after train…day after day.
No hope for this guy in the Engineering, Track or Mechanical disciplines. Hope Operating or Signal has a home for him.
You must be talking about the school of going fast on gravel roads that have become corduroyed. I was never convinced that that was beneficial. But there is the phenomenon of rocking jumbo hoppers that is worse around 20 mph, and can be mitigated either above or below that critical speed.
The amount of crossing impact depends on the angle of the crossing intersection. A shallow angle has each wheel supported by the opposite shore of the gap before it completely leaves the first shore. But still, the loss of support represented by the gap allows some wear, which creates a depression. And the development of depression creates impact that further deepens it.
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Oooh, another insult! See if you get any Track and Time in this lifetime, buddy. And all those track lights? Must be dirty ballast problems. [swg]
Whadya mean, replace the endpost? (I already took the railroad home in my pocket.)[oX)][:-,][:-,]
I always thought the 2AM tracklight was just a badguess dispatcher getting lonely.[swg]
Isn’t there flange support through the gap or is that a special type of diamond? Even if there is flange support maybe there is also an impact issue as the weight is transfered to the flange. Isn’t there a little ramp that brings the flange into the flangway?