Low Speed One Way Diamonds

[NP Eddie]

Page A6 of the February 4, 2015 "Star Tribune" has a picture of the CP (SOO) and BNSF (GN) diamond in Crystal, Minnesota.  I realize that the February "Trains" had a picture of the low speed one way diamonds. How does the Monticello Local cross that diamond without derailing? The TC Division limits BNSF trains to 10MPH.

I was the Roadmaster's Clerk for the Northtown Roadmaster and rode that line in a highrail approximately 1989. 

Ed Burns

Happily Retired NP-BN-BNSF from Minneapolis.

[greyhounds]

O.W.L.S. = One Way Low Speed

https://www.arema.org/files/library/2008_Conference_Proceedings/Update_on_the_Use_of_Flange_Bearing_Technology_in_Special_Trackwork_2008.pdf

 

[mudchicken]

Ed: emphasis on "Flange Bearing" with a cast lip guardrail (which is why the low speed)...roadmasters are wary of any wheelset where the wheel flange is getting angular instead of round just like around switch points - they climb)

[Deggesty]

greyhounds

O.W.L.S. = One Way Low Speed

https://www.arema.org/files/library/2008_Conference_Proceedings/Update_on_the_Use_of_Flange_Bearing_Technology_in_Special_Trackwork_2008.pdf

 

 

As I was reading through the text, I was thinking that pictures would help--and at the end, there are photographs of installations, which give a better understanding of how the frogs work.

Thanks

[NP Eddie]

Johnny and all:

It is said that a picture is worth a thousand words. I see that the low speed rails are raised about 2 to 3 inches over the fast route, which is why the BNSF has a 10 MPH restriction on that crossing.

Ed Burns

 

[daveklepper]

Even at the low speed of 10mph. there would be quite a bump, because as a wheel on the low speed train passes over the flhangeway of the high speed rail, there is no support directly under the wheel, either flange or tread, only support slightly to each side.   But this is not much different than a regular frog.

For the high-speed route, the frog is like it is just not there.

[JoeKoh]

There are "sheepjump" diamonds for the ND&W at Defiance and the I&O at Hamler.Their trains are limited to 10 mph.

stay safe

Joe

[Paul_D_North_Jr]

daveklepper

Even at the low speed of 10mph. there would be quite a bump, because as a wheel on the low speed train passes over the flhangeway of the high speed rail, there is no support directly under the wheel, either flange or tread, only support slightly to each side. . . . [snipped - PDN] 

No, the wheels on the low speed train are bearing on the wheel tread, which is bearing on the 'head of the rail' portion of the frog, until that portion has to drop away at the main route's flangeway.  Then, while the wheel crosses the flangeway, the weight is transferred to the flange riding on the main route's rail, until the far side of the flangeway, where the wheel tread is again bearing on the 'rail' portion of the frog.    

Refer to, enlarge, and then study Figure 3 of the OWLS diamond on page 15 of 22 of the above-linked AREMA paper (too bad it doesn't yet have any wheel wear on it to better illustrate the bearing points and planes).

- Paul North.   

[Norm48327]

Paul_D_North_Jr

 

 

daveklepper

Even at the low speed of 10mph. there would be quite a bump, because as a wheel on the low speed train passes over the flhangeway of the high speed rail, there is no support directly under the wheel, either flange or tread, only support slightly to each side. . . . [snipped - PDN] 

 

 

No, the wheels on the low speed train are bearing on the wheel tread, which is bearing on the 'head of the rail' portion of the frog, until that portion has to drop away at the main route's flangeway.  Then, while the wheel crosses the flangeway, the weight is transferred to the flange riding on the main route's rail, until the far side of the flangeway, where the wheel tread is again bearing on the 'rail' portion of the frog.    

 

Refer to, enlarge, and then study Figure 3 of the OWLS diamond on page 15 of 22 of the above-linked AREMA paper (too bad it doesn't yet have any wheel wear on it to better illustrate the bearing points and planes).

- Paul North.   

 

The OWLS diamond at Durand shows the wear incurred from that. Guaranteed employment for the welders as repair is a constant chore.

[Andrew Falconer]

How permanent are these O.W.L.S. diamonds?

Eventually a safer diamond has to be installed.

[Paul_D_North_Jr]

OWLS diamonds are as permanent as any other crossing diamond - actually more so, since they need less maintenance than the more conventional cast manganese or bolted built-up types and hence last longer. 

Although Norm notes above that the one at Durand needs welding often, I'm told that the other types need even more welding.  That's the biggest reason to develop and install them - to reduce the costs of that maintenance, and especially the loss of even more valuable track time while that is occurring on the main route. 

There doesn't seem to be any safety issues with the OWLS diamonds.  They're not for everyplace - all are low-speed, low-frequency = 1 to several times per day crossings (short line, regional branch line, industry, etc.).*  Busier crossing routes still have the conventional type diamonds.  Shallow angle crossings can sometimes be replaced by a pair of turnouts, and get added flexibility for interchange, etc. 

*i've asked about the negotiations with the crossing railroad for the main line railroad (if different) to get an OK to install these, esp. if the crossing railroad is "junior" and has the financial responsibility for maintaining the crossing anyway.  I've been told that safety has not been a big issue, but that coming to an acceptable agreement on sharing the installation and on-going maintenance costs has sometimes been a challenge - never stopped the proposal, but it takes a while sometimes.

- Paul North.    

[CShaveRR]

I have seen a couple of OWLS installations (including the ones in Durand...how the mighty have fallen!), and have noticed that there are markings on the through rail made by the flanges.  I think there will eventually be a groove worn across the rail at that point, though wear of the railhead from the busier line should kind of equalize things.  A good installation shouldn't be any more jarring than an ordinary diamond for the low-speed track.

[daveklepper]

Paul, what you wrote is essentially true for say a 60-degree diamond, but not for a 90-degree.  Because on a 90-degree diamond there comes a point where both the tread and the flange are directly over the high-speed route's flangeway.  And even if the flangeway were to support the flanges of the high-speed route, this suport would be lower in height than required for the low-speed rout.  But flange support of the high-speed route is not required anyway.   So, yes, there is a bump for the low-speed route, but need not be greater than a regular diamond.

[Paul_D_North_Jr]

Correct, Dave - even for angles other than 90 degrees, there seems to be a slight groove resulting in the running rails of the main line.  Nevertheless, that seems to be acceptable - even preferable than a traditional frog, all things considered - to the Class 1's that have tried them.

For more info on all this - including a better response to Mr. Falconer's concerns - see slides 23 & following of this May 14, 2010 presentation on "Overview of Flange Bearing Frogs" ("Flange-bearing frog technology: Experience and future plans on the BNSF Railway") by BNSF engineering official Michael N. Armstrong (35 slides, approx. 3.08 MB file size in this 'PDF' electonic format):

http://railtec.illinois.edu/CEE/pdf/PPT%27s/Spring10/Amstrong.5-14-10.pdf 

To your point, from slide 24: "Grooves will develop in running surface of higher speed route and welding may be required".

It's a great and informative presentation on the subject. 

- Paul North. 

[Norm48327]

Paul,

I've not thought to ask my track foreman friend, but wouldn't simply making the "ramps" on the low speed route higher prevent the flanges from hittig the running rails on the mainline?

[MidlandMike]

About 10 miles NW of Durand, is Owosso, MI, home of Steam RR Institute's #1225.  Also they get occasional visits by other big steam, like ex-NKP #765.  Are their restrictions on steam locos using the OWLS diamonds?

[Semper Vaporo]

Norm48327

Paul,

I've not thought to ask my track foreman friend, but wouldn't simply making the "ramps" on the low speed route higher prevent the flanges from hittig the running rails on the mainline?

 

The train on the crossing route would have to be traveling pretty fast to get a bit of a jump off the cliff of the missing flange support or it would just present a double-bump.... One as it rolls off the flange support and lands on the main route railhead, then another bump as it rolls off the main route railhead and falls into the flangeway of the main route.

 

By making the flange support of the crossing route to be equal to the height of the main route, there is only the bump of falling off of the main route railhead into the flangeway of the main route... a much smaller bump than the double-bump, or the huge bang of falling off of the flange support, flying over the railhead of the main route and into the flangeway of the main route.

 

I suppose if one could get the crossing route train to go fast enough it might be able to fly all the way across the gap and there'd be no bump in the night at all.