[soapbox] After watching a video containing bulkhead flat cars loaded with wood products I wondered what the advantage is of the centerbeam flat car for the same type of loads? Wouldn’t there be the advantage to the standard bulkhead car since the centerbeams warn of tipping if not loaded or unloaded evenly?[banghead]
I would think a major advantage is that the centerbeam makes it easier and quicker to tie down the loads of lumber so they won’t shift sideways. If you think about it, a standard bulkhead flat provides no inherent lateral restraint. When a stack of lumber did shift and extend beyond the clearance envelope, it became a major pain to get the load corrected. Fortunately they rarely shifted enough to damage other trains or structures before being noticed and set off, but the hazard was real.
With a centerbeam, each side of the car has to be loaded and unloaded separately. There will be temptation to complete one side before moving on to the other. The car might still stay upright, until the forklift operator gives it a nudge as he loads the first pallet on the next side (or unloads the last from the first side). A straight bulkhead flat is not as susceptible to that additional sideways force.
On balance (pun intended) the centerbeam is a better design. If someone got careless and caused the car to tip over, it was away from the main track so other trains were not endangered. Admittedly it would be nasty for a worker in the lumber mill or yard who happened to be beside it as it tipped, hence the warning about tipping is displayed prominently on both ends of each car so it is hard to forget.
John
I believe - but can’t demonstrate or prove at the moment - that the centerbeam has a slightly lighter tare or empty weight than a bulkhead flat, hence can carry a little more payload, and/ or may be a little cheaper to build and buy. The reason for saying that is in the name. From a structural engineering perspective, if you look at a bulkhead flat, the deck is fairly thin. It takes a lot a heavy steel beams running the length of the car between the trucks to provide a deck that thin with enough strength to safely carry the load. In contrast, the centerbeam uses that tall partition in the middle as a beam - and being around 10 times as high at the bulkhead flat’s deck, it can theoretically achieve the same strength with about 1/10 as much steel in the beam-type elements. The thin top member which is in compression needs to be checked and maybe braced so it won’t buckle under maximum loads - that’s part of what those vertical members are for, as well as carrying the vertical shear forces into the top and bottom members.
John/ cx500 above mentioned the ease and security of tie-downs. Many centerbeams that I see have built-in retractable cables mounted on the vertical members or the top of the beam to facilitate that.
Centerbeams do have to be unloaded from both sides, and carefully to maintain their balance. For many shippers with forklifts that don’t reach much more than 4 to 5 ft. = halfway across the railcar, or which can’t lift an entire section, that’s not much of a disadvantage anyway - they’d have to unload from both sides anyhow. But for someone with a big lift or an overhead crane - that could be a hassle.
The ‘stick figure’ people in the tip-over warning stencils on the inside end bulkheads of the centerbeams have been kind of a running joke with my daughter for many years now - I have a small collection of photos of several different variations. Look at one the next time you can get a good look at one - they’re not all the same, surprisingly.
- Paul North.
Center beam flat cars are much easier to load/unload plus they can carry more product than the bulkhead flat cars that are much heavier.
Another advantage of center beams is tying the load down. You have cables and their plastic corner protectors which is much faster to secure.
The AAR open top load rules pertaining to loading bulkhead flat cars makes carrying lumber is expensive due to banding material and labor. The people loading the cars have the expense of the banding plus the people unloading have the expensive of disposal. Plus banding can hurt someone in several different ways. If the load on the bulkhead flat is not loaded to the specific AAR open top load rule, it can be rejected in interchange. The receiving railroad does not want to adjust or resecure the load.
While I was at Thrall Car, we applied the loading/unloading instructions on both ends of the car in English, Spanish and French.
The weight difference between a 62-foot (inside) bulkhead flat car and a 73-foot (inside) center-partition car of the newer truss design is very impressive. One of UP’s newest bulkhead flat cars has a tare weight of 83,600 pounds, while a CHTT FBC weighs only 60,300 pounds. Since both have a 286,000 pound gross rail load, their load limits are 202,400 pounds and 225,700 pounds, respectively. That’s a good ten tons of payload.
In spite of the obvious load securement and payload advantages of a center-partition car (I won’t call them “Center-Beam”, because that’s a trade name used by one of at least three builders out there), I hate 'em. Because the supporting structure is not down below the car, these cars are relatively (if not absolutely) top-heavy. Empty cars of this type are probably the most prone of any type to string-line derailments, and also the easiest to pop off the rail should those long, movable drawbars bypass (trust me on that one!).
Lumber likes to move around in transit. When I worked for a lumberyard near an interstate highway, we did a bang up business with truckers, helping them restack, and/or move lumber that had shifted. The center partition cars keep the load where it’s supposed to be.
Bulkhead flats are miserable cars. They have the weight of the bulkheads plus the structure to tie the bulkheads into the center sill. It makes for a car with a huge polar moment of inertia. A center beam car doesn’t need nearly as much structure in the bulkhead because the center beam hold the ends in place. The net effect is a car that is prone to some viscous hunting when it’s empty. In fact, there are usually TT speed restrictions for cars moving empty bulkhead flats.
Carl, that’s exactly the kind of data I was looking for, and hoping that someone like you would provide - thanks !
Note that the center-partition car is about 17 % longer than the bulkhead flat car, but weighs only 72 % as much/ 28 % less, and so can haul 23,300 lbs. = 11.65 tons = 11.5 % more than the bulkhead flat.
The Mechanical Designation Code (FBC) and Car Type Code (F483) can both be found in the back pages of your aging copy of the Railroad Equipment Register. I don’t have mine available right now but I do know that the Car Type Code is related to dimensions and weight.
Try page 261 of https://www.railinc.com/rportal/alf_docs/UmlerReference/UmlerDataSpecs.pdf for more info on the car type.
Here’s the “F” section
Flat Cars ETC F_ _ _
FIRST NUMERIC:
0‐‐Not Used
1‐‐Less than 155,000 pounds load limit
2‐‐155,000 to 184,999 pounds load limit
3‐‐185,000 to 199,999 pounds load limit
4‐‐200,000 pounds load limit and over
5‐‐Equipped for pipe loading only
6‐‐Equipped to handle frames (auto/truck)
7‐‐Single deck, pedestals and tie downs for saddleback loading
8‐‐Single deck, tie downs, without pedestals
9‐‐Not Used
SECOND NUMERIC:
*0‐‐FM
1‐‐FMS, standard draft gear/solid drawbar
2‐‐FMS, equipped with cushioned draft gear/underframe
3‐‐FD
4‐‐FB
5‐‐FBS
6‐‐FW
7‐‐FL
8‐‐FBC
9‐‐FDC
THIRD NUMERIC:
0‐‐Not Used
1‐‐Less than 53’ inside length
2‐‐53’ and less than 60’ inside length
3‐‐60’ and less than 75’ inside length
4‐‐75’ and less than 85’ inside length
5‐‐85’ and less than 89’ inside length
6‐‐89’ and over inside length
7 through 9‐‐Not Used
FB‐‐Bulkhead flat cars equipped with fixed or permanently attached movable bulkheads or ends a minimum of three feet in height and flat floor for general commodity loading.
FBC‐‐Flat car constructed with a center beam above the car deck from bulkhead to bulkhead.
FD‐‐Depressed center flat car of special construction having the portion of floor extending between trucks depressed to provide necessary overhead clearance for lading.
FDC‐‐Flat car, constructed with a center beam above the deck from bulkhead to bulkhead and having the portion of the floor extending between trucks depressed to provide additional volume capacity.
FL‐‐Flat car with or without straight deck consisting of two trucks fitted with cross supports over truck bolsters; the trucks are connected with a skeleton or flexible frame or solid underframe fitted with supports for transporting lading loaded lengthwise, e.g., logs, pip
Thanks, Don. I was going to add that AAR’s Car Type Code is also related to the AAR Mechanical Designation (yes, Paul, they’re both governed by AAR), but your summary for the flat cars handled that nicely
Paul, in looking closely at that photograph by my friend Dave Casdorph, I find that more plausible load limit and light weight are 223500 and 62500, respectively. I’m not sure who supplied the bogus numbers there, but it sounds like some pretty extreme dyslexia!
Thanks once again, Don, for that extensive and thorough explanation - and Carl for the corrected data. [tup] Truly, with you guys it is “Ask, and ye shall receive”. It makes this Forum lot more fun and informative - that’s my chief ‘currency’, I believe. [“Will work for information !”, with apologies to Mookie [swg] ]
In one of his posts yesterday, Don had mentioned his concerns with the ‘tracking’ of the bulkhead flat cars. I looked through some NS documents on-line, and found in the ‘System’ TimeTable a rule that limits those empties to 45 MPH, but specifically excludes the Center-Beams from that restriction. Maybe later on I’ll post the link and a quote of that.
But this discussion is really interesting and instructive - 'a ‘teaching moment’, if you will - for those of us who think the world is or should be 'black-and-
Always glad when I can be of help, Paul–and I, too, enjoy learning here.
On our little pike, bulkhead flat cars and center-beam cars each have their own little section of restrictions. Empty bulkhead flats are restricted to 40 m.p.h (interesting that that’s slower than NS, which is not known as being as fast a railroad in general as ours is), unless the cars are equipped with constant-contact side bearings–then it’s 50. Those bearings must help mitigate the hunting problem.
Empty center-beam cars are restricted to 50 across the board (or lack of boards, in this case).
I think you’ll also find that trains with these empties are restricted in speed because of aerodynamic drag, which has to be horrendous on these “double-masted” cars. We know they sail pretty well in our yard when the wind hits them right. I’m not aware of any accidents caused by the cars that have blown back out onto the lead after having rolled into the clear once, but a few have been avoided because of the watchful eyes of car retarder operators…
Interesting insights, Carl. I’m sure that keeping an eye on those ‘sail-cars’ prevents you from becoming . . . ‘bored’ [;)]
Heres’ the Norfolk Southern rule that I was referring to - from the ‘‘SYSTEM SECTION’’ TimeTable Number 1, Effective August 4, 2008, at - http://blet73.org/System%20Timetable.pdf - specifically, GENERAL SPEED RESTRICTIONS, SP-1. SPEED RESTRICTIONS - CARS, on page 1:
Empty bulkhead flat car and/or empty woodrack car, foreign or system …45
EXCEPTION: Restriction does not apply:
1. If car is shown on train consist, but is not identified as restricted equipment. (Bulkhead flat cars and woodrack cars equipped with constant contact side bearings are not restricted and will not be identified by the computer as restricted equipment.)
2. To center beam flat cars.