Level Junction - Diamond Design

[Crummy]

I've searched the web and have not been able to locate information on standard gauge railroad diamond crossing design.  I'm looking for information on they design perimeters, special tracks, tie layout, and pertinent information common to the industry today.  If you can lead me to an information source on the web that would be appreciated.

Thanks

[Juniatha]

Hi Crummy

                     You may want to check this-here site - it cover pretty much all aspects of design and construction of road bed and rails and their various forms of crossings, switches ... geometry, welding, materials, tools, vehicles …

It's in German but there are many photos and some things should be self-explaining, right?

Design differed quite widely, internationally, depending not only on parameters of locomotive and cars axle loads, wheel base, speeds but also local development technical lines followed, available means, again on anticipated speeds and loads and - last not least - what engineers of a certain railroad company considered best suited in view of their demands - just for instance as concerns use of pre-fabricated cast steel reinforcement elements and welding. This implies a solution may not necessarily have been best choice in an absolute sense but more often was - still is, in spite of CAD – a choice made by people with all the limitations of knowledge and human error). After all, no technology is complete - it's all in a constant flow of improvements towards an ideal of perfection that remains a silver streak at the horizon ...

See

http://www.gleisbau-welt.de/site/gleisbau/gleis.html

http://www.gleisbau-welt.de/site/weichen/weichenkonstruktionen.htm

http://www.gleisbau-welt.de/site/weichen/weichengeometrie_kreuzungen.htm

Regards

           Juniatha

 

 

 

 

[cx500]

Most diamond crossings are designed individually.  When two railroads intersect, the angle is determined by their relative alignments.  The angle will be defined in degrees, minutes, and even seconds.  Shallow angle diamonds may have movable point frogs.  Tie layout will depend on the crossing angle, relative traffic density, and railroad preferences.  There may be an AREMA manual giving broad outlines of suggested practice, but really, each diamond tends to be designed to fit the specific location.  Often spare frogs are kept in the immediate vicinity in case one breaks.

John

[henry6]

Yes, each is designed individually but there are basics...check publications of Simmons Boardman publishing or advertisements in Progressive Railroading, or whatever the name of the professional magazines are today.  Local library may have something under civil engineering if not railroad engineering.

[mudchicken]

He'd be better advised to go look at AREMA's Portfolio of Trackwork Plans (Plan sets that go with Chapter 5 of the AREMA manual and look at the 700 series drawings.)

The WEB is not the answer usually, especially in cases where copyrighted material is needed...like the AREMA manual. Go to a College Engineering Library or cough up the $800-$1000.

http://www.arema.org/files/pubs/forms/AREMA_2010_Portfolio_of_Track_Work_Plans-TOC.pdf

UW-Madison would probably be the closest place for the cheesepicker.

 

[Paul_D_North_Jr]

The 700-series "Crossings" plans are on page 2 of 4 of the link that MC provided above. 

Current AREMA Member / non-Member prices for the Portfolio are $995/ $1,395 for the paper version, $595/ $745 for a CD-ROM (it's way cheaper to become a member !).  See: http://www.arema.org/files/pubs/forms/AREMA_2010_Portfolio_Order_Form-0111.pdf 

Or join the National Model Railroading Association and purchase a set of their "Data Sheets" on crossings. 

You might get lucky and find that kind of info in some MOW Standard Plans that have been digitized and available on-line - I'll look and see if some of my favorites (PRR) have been posted.

Sadly, not all college engineering libraries have the Portfolio or Manual of Railway Engineering anymore.  Last time I checked a couple years ago, Lehigh University - a famous engineering school, one which graduated many railroad engineers, and which was founded by Asa Packer, the same guy who started the Lehigh Valley RR - over in Bethlehem did not have them catalogued.  Talk about forgetting one's roots . . .

Since I'm feeling benevolent tonight, I'll take some time and post a recent illustrative photo or two* of one I designed and supervised almost 30 years ago - it's curved on both routes.  It sure was a lot of fun figuring out how to drill and bolt together 3 big 7" high x 9" wide timbers to support 1 pair of the rails through it . . .

(*Said photos cost me just over $500 to obtain because I accidentally locked the keys to the rental car in the trunk - it's a long and sad story, which can be summed up thusly: Don't do it !)

- Paul North. 

[Paul_D_North_Jr]

Double-curved crossing frog at former B. F. Goodrich Co. plant, Pedricktown, NJ (oppposite Wilmington, Del.)
Installed July 1982 by W. E. Yoder, Inc., Kutztown, PA, J. Roger Jones, Foreman.
Note 3 timbers bolted together under main route's plate; also, excavation down to 3 ft. below rail and rebuild up from there.

 

Brain-teaser:  What's different about some of the track bolts in the rail joints just outside of the crossing frog itself ?

- Paul North. 

 

 

[blue streak 1]

Paul_D_North_Jr

Double-curved crossing frog at former B. F. Goodrich Co. plant, Pedricktown, NJ (oppposite Wilmington, Del.)
Installed July 1982 by W. E. Yoder, Inc., Kutztown, PA, J. Roger Jones, Foreman.
Note 3 timbers bolted together under main route's plate; also, excavation down to 3 ft. below rail and rebuild up from there.

 

Brain-teaser:  What's different about some of the track bolts in the rail joints just outside of the crossing frog itself ?

- Paul North. 

 

 

PDN:  Is it that all bolt nuts are on the guage sides except for 2 outside connections?

[ChuckCobleigh]

Hex head?

[Paul of Covington]

    In answer to the brain-teaser, the only thing I see different is that the nuts on the left joint near the gate are arranged in-out-in-in-out-in rather than in-out-in-out-in-out.

    Question:  the flange guides (if that's what they're called) approaching the diamond on the track parallel to the fence seem to be different lengths.   I noticed this when I was wondering why the crossties under them were skewed.   Is this so, and why?

    I never appreciated how complicated a diamond was until studying those pictures.

[mudchicken]

Ties are skewed to fully support the joints and castings. You are trying to guide the wheels in the flangeways across an as-rigid-as-possible manner. The wingrails and bevelled approaches are set opposite each other to keep down the truck hunting lateral forces on the frog pices and parts as the wheels approach the crossing frog.

These things are subject to a lot of mechanical actions that make them the most brittle thing in the track structure. You do all you can to strengthen them to extend their service life.

[Anonymous]

I think crossings are one of the most intersting features on a railroad track.  Interesting is the difference in behavior and design when going from a medium angle crossing to a 90-degree crossing like in the photos.   In medium angle crossings, the ties are set to a compromise angle and then evolve back to normal as they leave the crossing.  With a 90-degree crossing, there can be no compromise, so one track has to sit lenthwise to specially enlarged ties as seen here.  I don't know what those would be called. 

Also, with a 90-degree crossing the wheels have to jump the big gap of the opposing flangeway, whereas with medium angle crossings, the wheel encounters new support on one side as it leaves the old support of the opposite side.  So it does not need to jump off a cliff as it crosses the gap.

I have noticed a lot of variety in the details of crossings.

Probably the most interesting track features are puzzle switches, but that is another story.    

[Paul_D_North_Jr]

For some of those details, see the PRR Standard Plans for Crossings from Dec. 1913, Nos. 61620 - 61622 inclusive for various angle ranges, at about 1/3 of the way down this webpage: http://prr.railfan.net/standards/standards.cgi 

- Paul North. 

[daveklepper]

Talking about puzzle switches, the new Jerusalem Light  Rail has an in-pavement, pavement used by trucks busses and cars, SLIPSWITCH!!!!!    Something I never saw on any existing or past North American or Euorpean streetcar, interurban , or light rail station.   It is located just north of the Givat Havtar Station, which has a parking lot.  The lead to the carbarn and shops takes off as a wye, and the slipswitch is on the southern leg, permitting access to both northbound and southbound tracks.   Th north leg of the wye goes to the northbound track, and then there is a facing crossover, the only one on the system except for the terminals so access can be had from the southbound track.   All points on all switches throughout the system are motor controlled.   No spring switches or manual points.   The frog angles are at angles chosen so movable point frogs are not required.

[CSSHEGEWISCH]

Double slip (puzzle) switches are uncommon enough on transit operations (CTA Blue Line has one or two at O'Hare but I'm unaware of others) so a double slip switch in the street is an absolute rarity.  Got any pictures of this installation??

[bigduke76]

i can think of two cities which had traction double-slips in pavement, and they were curved as sharply as most traction turnouts, which chicago's o'hare ones are not.   los angeles had one at the old PE station at 6th & main; it was not in a street, but was in pavement, i presume to accomodate buses.   this one was preserved, and is now in use at Orange Empire museum in Perris (ehymes with Paris) CA.   i also saw several in use in pavement at the west end of the shops in Boston 20 years ago; don't know if they're still there or not.   one of them had had one of the four curved rails removed; it was a one-and-a-half slip switch!   there was also one on the South Brooklyn ry. on its trackage rights into Bush Terminal but it was a standard RR double-slip although quite sharp;  elctrified for poles with the two wire frogs about 10 ft. apart.