Is there a speed limit when crossing the raised portions of these diamonds?
I witnessed a train going at a pretty good clip over one.
From a May 14, 2010 presentation at the University of Illinois - Champaign-Urbana by Michael Armstrong of BNSF on Flange-Bearing Frogs generally:
FRA Track Safety Standards, Section 213.137(d), currently states:
“Where frogs are designed as flangebearing, flange-way depth may be less than that shown for Class 1 if operated at Class 1 speeds.”
Of course, per Sec. 213.9 the FRA Class 1 speeds are 10 MPH for freight, 15 MPH for passenger (you didn’t say which kind of train it was . . . ). And I’ll accept that your observation was correct that the train was operating over the route of the frog that involved the ‘flange-bearing’, not the other ‘main line’ route.
10 mph or less over the flanged tread bearing side, much more over the normal side.
Now I’m completely in the dark.
I thought frogs were supposed to support the flanges in both directions, but this conversation makes it sound like one direction is higher than the other. Is it the case that some diamonds favor one direction with a smoother path?
Also what is meant by an “OWLS” diamond?
No, most frogs normally support the treads - only - of the wheels, just different portions as they traverse the gaps. Traditionally, the flanges are supposed to not touch the bottom of the flangeway.
However, recently designs that do depend on the flange carrying the wheel weight - for a smoother path, as you surmise - have appeared and been placed in service on an broader experimental or ‘beta-test’ basis. So far, only 1 direction or route does that - the other is normal. And yes - the flange-bearing path is a little higher than the other one.
“OWLS” = One-Way Low Speed diamond.
Link to Power Point slides and photos in ‘PDF’ format from the presentation by MIchael N. Armstrong of BNSF that I referenced above, which should answer a lot of your questions - 35 pgs., approx. 3.1 MB in size:
http://ict.illinois.edu/railroad/CEE/pdf/PPT’s/Spring10/Amstrong.5-14-10.pdf
- Paul North.
“There’s not that many of these around - where was this one ?”
Durand, MI. The low speed track crosses the CN mains 1&2. CN runs 40 MPH through town and across the OWLS (They have the high speed side of the diamond.) because the town is a quiet zone. The southbound train was a freight, and was doing about twenty.
I guess I’ll have to get back to Durand and see that for myself. I find it absolutely amazing that such a diamond would be put there. I guess when they spin off a line, they really spin it off!
Carl,
I took photos while they were installing it. I don’t know how to post them on here, but if you’d PM me your email I’d be willing to share some of them.
CN still owns the Durand yard but leases it to HESR. CN, HESR, and GLC (formerly TSBY) all interchange there. Only a couple of trains a day use the low speed side.
Thanks, PDN, for the link to the PDF, but you may have opened up a can of worms by giving me too much information. The lift frog had me baffled for a while, till I got hit by that beefy guard rail. The wheels on the diverging route actually jump over the main rail, is that right?
I believe the BNSF/Wisconsin and Southern diamond at Crawford (Prairie Du Chien) was/is a flange-bearing design, BNSF could do 40-50 over it, while the WSOR side was 10mph. Rocked pretty good going over it, even going less than 10…
Yep. [tup]
Unless the frog angle is close to 90 degrees, they create a cross-level problem, too - the flange bearing frog’s side is 1-1/2 to 2 inches higher than the opposite ‘normal’ rail. Also, the ‘ramp up’ is pretty short compared to the speed of the train - 10 MPH is 14.7 ft. per second, so even a 5 ft. long ‘ramp’ would be a 2" bump up in about 1/3 second - and then right back down again. i asked a question about that during the presentation, and the answer was that it had the worst effect on rigid-axle vehicles, such as Hi-Rail trucks, MOW equipment, etc.
Randy’s post raises the other matter that I asked about - the ‘institutional’ cooperation/ coordination between 2 different railroads, when the result is that 1 of them will be held to 10 MPH speed over the diamond for as long as it is in place, plus the experimental nature of the thing, of course. I was told that is indeed a challenge, which is why most installations have been where the same railroad owns both the main and the secondary track - but here, perhaps the BNSF paying for the crossing and the WSOR not needing to go any faster correlated to make it happen.
I’m not aware that CN has any, but CSX and BNSF were the 2 biggest users as of May 2010.
- Paul North.
Paul: Chenoa, IL (UP) has one (w/TP&W) that was the focus of an AREMA presentation by IDOT’s Mike Garcia in 2008…The mess at Gilman is being looked at (CN-IC/TP&W …3 x-ing frogs) inside the interlocking plant (1-Stl main & 2-Effingham main) with the other improvements CN is planning there to the north of the crossing.
Randy’s post above got me to thinking some more about this - sometimes a dangerous activity [swg] - for a while this morning, with the following results:
The ‘ramps’ up for the flanges in the flange-bearing frogs - what the wheel and car are actually ‘feeling’ - are awfully steep, when compared to the rates that are implied as the maximums for the same Class I track by the FRA’s Track Safety Standards in 49 CFR Part 213. Specifically, under Sec. 213.63 - Track Surface, a ‘runoff’ in the track ‘surface’ shall not exceed 3-1/2’’ in 31 ft. When we consider that a flangeway has to be at least 1-1/2’’ deep, and should be closer to 1-7/8’’ or 2’’ when new, that indicates to me that the ramp which raises the flanges up should be at least (1.5 / 3.5) x 31 = 13.3 ft. long, and maybe as long as 17.7 ft. for a 2’’ depth. Similarly, the maximum deviation at the mid-point of a 62’ chord - which would be 31’ from each end - is 3’‘, which would imply a ramp of from around 15 to 20 ft. long. Likewise, the maximum change in cross-level over a 62’ chord is 3’', which would imply a ramp length of from 31 to 41.3 ft.
Carl,
The rest of the story:
As you already likely know, the diamond in Durand is the intersection of the Flint and Holly subdivisions. Most of the eastbound trains are on main one, which I believe is the north track, and switch using the Port Huron Wye (the northeast quadrant). Trains destined for Detroit use the south main and back over the diamond to switch the yard. Since the demise of the Flint/Flatrock train the high wye (south east quadrant) does not see a lot of use. Most northbound CN trains take a left turn here on their way to Chicago. A new #20 turnout was installed a couple years ago to facilitate that movement.
So; that leaves us with CN switching moves and GLC movements over the low speed portion of the new diamond. It was a GLC move that I thought was going too fast.
Paul,
Thanks for the link to a very informative presentation from a BNSF civil engineer. I don’t pretend to fully understand all that was presented, but it does give me ‘food for thought’.
I know a local track foreman, and he has taught me a lot. I told him I was not satisfied with standing at a crossing catching pictures of freights, and wanted some photos of the guys who break their backs to keep the railroads running. MOW, and track things are now much more important. I can only hope my digital photos will be preserved.
Paul:
Before I left WSOR in 2005, the only customers on the west side of the Crawford diamond were the transload facility on the Prairie du Chien island, and a plastic lumber loading area, plus the BNSF interchange. There was talk then of relocating the interchange to the northeast quadrant, and relocating both customers (the plastic lumber loading wanted a bigger and better area, and the transload wanted to get off the island due to flooding issues). We never went out there more than three times a week, while BNSF had about 15-20 trains/day, so BNSF wanted to avoid doing a lot of maintenance on the diamond, which had been reinstalled after being pulled out in the 1980s. I’m sure that to both roadmasters, the flange-bearing diamond made better sense from both an operation and maintenance standpoint (if I remember correctly, it was a 10mph railroad from the diamond to the end of track on the island).
on a historical note, i recall some ‘owls’ frogs on trolley lines back in the 1950’s. i took a slide of one at the end of SF Muny’s ‘M’ line when the end was a simple stub track, before it got PCC cars. both branches of the one turnout got equal use, so the flanges had worn quite a groove in the running surface of the ‘low’ rail. the frog must have been part of a little-used crossover when the line extended further. -arturo (while in mexico(
We have two fairly close to each in Northern Indiana.
Walkerton, IN - CSX / Pioneer. CSX is ex B&O and has the fast side on a double track main with 60+ trains a day. Pioneer is ex NKP branch with spotty service to a single customer.
Thomaston, IN - NS / CKIN. NS is ex NKP main with 40+ trains a day. CKIN is a grain hauler with traffic depending on grain cycles.
The slow speed flangeway is raised to the height of the fast speed railhead. This allows the high speed line to run through at speed on continuous rail. The low speed is max 10 MPH and the wheel rides on the raised rail with the flanges providing some support across the larger gap.
Late yesterday I did go back and review the AREMA Proceedings for 2008 and 2006. Although I haven’t yet found the presentation referenced above by MC, I did find - contrary to my previous posts - that at least some of these frogs have ramps at a slope of 1:180 - that’s 1" in 15’, or about 0.55 %. So for a 1-1/2" deep flangeway, that ramp would be around 22.5 ft. long, and for a 2" deep flangeway it would be about 30 ft., which seems a whole lot better to me. At 10 MPH the vertical rate of climb would be around 1" = 0.08 ft. per second = 5 ft. per minute or about 0.06 MPH, which is pretty slow of course.
However, the comparatively sudden acceleration to that rate in a fraction of a second as the bearing area of each wheel comes to bear onto the gently rising ramp