The current (March 2014) issue of Trains Magazine has an article about the NS Bellevue yard. The yard currently has 2 tracks, both feeding the same 42-track bowl. After a $160 million expansion, there will be 2 bowls with a total of 80 classification tracks. Now that will be a Super Bowl set-up.[:-^]
This leads to some questions, as this is a railroad forum after all. The second car humped into the bowl glides down the hill, and gently couples with the first one. How is the first one placed? Is it just pushed down the hill, and stops where it stops, catching the remaining cars? Does it stop against a bumper? Are the brakes set?
The aerial photo seems to show a hump set-up, where all the classification tracks dead end. There is also a set of switching tracks that are open at both ends. Would that second set be flat switching only? Do hump switched cars always have to be pulled back up the hill after switching?
A lot of bowls have “Dowty” inert retarders set on the rails to 'catch" the first car in the track. Old school is a switchman sets a “skate” or portable wheels stop on the first car.
The aerial photo on the opening spread shows the bowl under construction. Those tracks will eventually lead up to the hump. Note that the article says that the yard will eventually have some 80 tracks, virtually double its current size. You can see the grading leading to the outermost track.
The actual hump is at the upper right of the image.
You’ll note that a number of new switches for other ladders have been set sans any other track at this point.
Expect there to be plenty of trial and error testing prior to putting the yard in everyday service. The standards used to design these things are well documented by the dowty retarder people, the railroad engineers and various old heads - NS will learn from the lesson at Buffalo and break this thing in gradually, adjusting as they go. The biggest variable has to be the worn draft and truck systems in play in a common carrier exercise.
I suspect that our resident hump operator Carl will say operating this new hump will be trial and error even for him ? Too many variables and unknowns no matter how well engineered. Bet NS will bring in several different location operators to tweak the operation. Too bad Carl canot be hired.
Around my old stomping grounds, you’ll hear a lot of reference to “posts”. As far as I know, that’s a strictly Proviso term for cars tied in a classification track to hold back the cars that will be classified into that track. The person on the pulldown crew is responsible for cutting off three (or more, depending on certain variables) cars at a specified distance from the far end of the track, and tying handbrakes on these cars to hold in the onslaught.
If a track goes clear (sometimes the cars are too hot to stay there, other times they don’t make a suitable post), the hump will have to post the track from its end–shove cars down to the proper position and tie the brakes.
Used to be different when we depended on brakes, skates, riders, etc. Been there, handled all of that.
Would guess that track skates would be long gone….most likely the trim job, as Carl pointed out, would either leave a bumper (post) or the hump crew would have to set them themselves.
We flat switch, and have a top end trim job who does the same thing, they pull tracks back to make room, clear full tracks when needed, and leave a minimum two car bumper when they do.
North Platte has two distinct humps and bowls. From the looks of this picture, all of Bellevue’s 80 tracks will be accessible from the one hump. And, in my opinion, that’s the way it should be handled–as one hump. I suppose there’s an option in the design for humping into the bowls separately, each from one of the hump leads. As a practitioner in a place where that was done at one time, one has to be very lucky with the trains that have to be humped, to get them to fit that procedure. After a while, it became impossible for us, with too many of the inbounds having cars to go everywhere in the yard.
Eighty tracks off one hump may be some sort of record. I can’t remember how big Conway was or is; Elkhart is 72 tracks, The old Bensenville was 70; Proviso was 69 at one point (now 66).