Sunday, March 8, 2015

High-Speed/Low-Speed Diamond, OWLS

(Update: the proper name for these asymmetric diamonds is OWLS diamond - One Way Low Speed. A nickname is a "bump diamond." Crandall Junction is another use of an OWLS.
A newer development is the Flange Diamond that allows track speed in both direction. Jay Junction between (UP+CSX)/C&EI and CN/EJ&E now has one.

Photo on CKIN Photos
I assume the Chesapeake & Indiana Railroad is a Class III railroad. It crosses the Class I railroad Norfolk Southern/Nickel Plate Road in Thomaston, IN. This view is looking east down the NS/NKP track. At first, I thought it was just an "artsy" photo. Then I learned that the purpose of the photo is to show that the NS rails are intact across the diamond.
Close up

A picture of the 21st Street Crossing illustrates that normally a diamond has gaps in both pairs of rails. There is a reason why railfans use the phrase "pounding the diamonds" when a train crosses a normal diamond --- they make a lot of noise when each wheel falls into each gap. For example, watch at 0:30 in a Brighton Park Crossing video. Even though the trains slow down for the crossing, that pounding causes a track maintenance nightmare.

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Another example of a traditional diamond is in the Blue Island Crossing between Grand Trunk Western (using the bridge on the right) and Indiana Harbor Belt (using the bridge more in the middle).

Photo on CKIN Photos
Back to the Chesapeake & Indiana Railroad and the crossing between CKIN and NS at Thomaston, the caption for this photo is:

The diamond at Thomaston is a High Speed / Low Speed type. On the NS side, the rails are normal, there are no breaks in the rail and is considered the high speed side. On the CKIN side, the flanges of the cars ride up and over the NS rails. In this picture, you can see the gap under the wheel of the hopper. This design is popular where high speed railroads cross slow speed railroads. Maintenance costs are much, much cheaper on this setup.
 Before I used the 21st street crossing photo, I looked at a photo I had taken in Gilman, IL.

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Then I realized this was a different type of asymmetric diamond design. Instead of raising just the flange, the secondary rails replace the web with a ramp to carry the wheels over the primary rail. There is probably also a ramp for the flange to hold the wheel up in the gap. Note that the width of the gap in a regular diamond is just the width of a flange. In these "raised secondary" designs, the gap would be the width of the whole wheel, not just the flange.

But this design is evidently still a maintenance issue. Note how many of the various track segments are bolted in so that it is easy to replace worn segments. CN/IC would use the primary track. So the TP&W would use the secondary track. But, unlike the Class III CKIN, the TP&W is probably a Class II railroad. So this design that lifts the wheel instead of the flange might be a high-speed/medium-speed design.

Update: Mike Snow Flickr Photo has an extensive comment describing the OWLS diamond in Defiance, OH where the ND&W/Wabash (10mph or below) crosses the CSX/B&O (track speed). "The secondary run flange bearing surface uses explosion hardened manganese castings." (The source posting has comments indicating where there are other OWLS diamonds.)

A posting about jump frogs has the comment:
Rick LeggettGroup Admin Flange bearing technology has been in use for quite a while now. I remember over 15 years ago, TTCI in Pueblo testing to see if the flange on rail car wheels would support the weight of 286K loaded cars. Once it was determined that they could, designs for 'leap/jump frogs' and 'OWLS' (One-Way Low Speed) at-grade track crossings (diamonds) came out. I don't know of any railroads that allow a higher speed than 10mph, for the flange bearing route though. The whole purpose of course, is to eliminate the 'gaps' of frogs & diamonds on the higher speed/tonnage side of the application.

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Joe Sichelstiel Gives the heavy used route a smooth ride at full speed and the same ride as a regular diamond on the less used route as long as they do the 10mph speed and the track surface will last longer as will the diamond(they usually last only 5-7 years, but the OWELS is supposed to last longer, we will see)
Randall Hampton Ţed Ģregory It might work well for VERY low cross traffic, like maybe an inactive line that still gets inspected by maintenance department trucks, keeping it intact for future use.

[I think it is going up and over. It is kinda hard to tell.]

At 1:53 the video shows a train going over the OWLS. In this post are quite a few comments about how well they will wear. It used to be that a FRA waver was required to install one that documented the secondary line was low usage. But now that the waver requirements have been dropped they are going in everywhere.

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