How often do freight cars need servicing, as in set out to the RIP tracks? Or I suppose the better way to ask this is what percent of cars coming through a busy flat classification yard need to be set out for RIP? Or where can I find out?
I am guessing that it is more frequent for earlier eras, especially with journal bearings instead of roller bearing trucks. But beyond that I am clueless.
Thanks in advance.
David. Here's a link to site about rip tracks. Should give you the information you're looking for.
http://www.carknocker.com/Rip_track.html
Jim
Thanks. A good read and I learned a lot from his stories, but I didn't get what I am looking for.
I am writing software to mimic "all the other jobs" of a railroad. Mostly it generates waybills, switchlists, and re-assigns cars/waybills on trains while in staging. I want to add in bad orders, but I need good statistics on bad ordering so that the software can randomly create bad orders that bear some semblance to reality.
David,
I was thinking some other things, but then:
BUT ON THE OTHER HAND... How big is your rip track and facility? That is the maximum number of bad order cars you can have in the backlog. How many crews fit in your facility at a time? If the guy from carknockers gives you the average rate of cars a one shift crew can handle in a week (call it: nc_csw), you got someplace to go now. The worst case maximum number of cars you could move in a week would be:
crews * 3 shifts * nc_csw
Then maybe you normally only run half crews one shift. This will tell you the normal rate of cars wearing out or being damaged. And for one week that would be:
crews * 0.5 * 1 shift * nc_csw
You could target a backlog (bad order cars in storage) that is half the capacity of your rip track, and temporally assign an additional crew or overtime to get the backlog back down to half the rip track capacity.
Then of course there would be random variations that would cause this to change, and a disaster now and then to really load things up. In the disaster mode if you run out of rip track space you will need to keep the bad order cars other places in the yard or even sidings while you reassign crews and put crews on overtime. It could be a pretty dynamic system, I think I am going to keep track of this my self for the future.
This is where I started thinking if you want to wander through it:
Maybe you can piece some things together. I don't have anything to help you with directly. But: 1) if the railroads had some kind of annual report that listed numbers of rolling stock in a) total and b) bad order, it might be a start. And 2) I looked at carknocker too, the guy running the site sounds like he likes to be helpful, maybe if you email him (if you didn't already) he can tell you the numbers of cars they would process in a week or month. ((Actually maybe he can tell you all you need to know.)) What does this mean?
I'm thinking... While we are waiting for a real answer I will ponder a bit, as if I was a real railroad, sort of. There are a couple variables here. One is the percent bad order cars you are willing to tolerate representing lost revenue, and the other is how much you are willing to pay for the facilities and personnel to be on the ready to repair cars when they break. You could keep a facility that could operate 24 hours a day with full crews at some maximum rate to clear excess backlog. This might need to be significantly more that the expected maximum rate of cars wearing out, and cars damaged by accidents or something. This could include overtime shifts, and maybe reassigned personnel and additional crews if that is practical. Then on the other hand when things are not so busy be able to run in one shift and keep crews busy in full time. ARRGH.
Have fun,
Charles
Thanks Charles, you got me headed in the right direction. I found some related data, plus a quick survey of several flat classification yards in Nevada, California, and Oregon got enough to start working out something believable if not accurate.
For the modern era 3-5% of total cars owned are bad ordered, many in storage or damaged beyond repair. From the end of USRA control until at least sometime in WWII looks like 5-10% of total cars were bad ordered, again most in storage or damaged beyond repair.
Trying to back out cars/yard from various sources (including freight car maintenance costs per year) I'd have to guess around 0.1-0.5% in the modern era. Of those 50% are ladder treads not meeting safety standards!
From the GoogleEarth yard survey, I estimate the capacity of the car shops and associated tracks to be about 5% of the classification capacity (number of cars at any instant). A number of the cars at the shops look like permanent fixtures.
Doing some selective compression I come up with a target of 1% of cars going through the yard as being bad ordered. That would be 2-3 cars per session. Most of those would only spend a few hours in RIP. This would be frequent enough to make it look like there should be a RIP facility at the yard, yet few enough not to bog down the yard operator(s). Now I say target, because there is a rule I use about actual derailments on my pike - all the cars suspected of contributing to a derailment are automatically bad-ordered until they can be thoroughly inspected and fixed if necessary. So I'm hoping that bad-ordering due to real model events doesn't blow away my target!
Freight cars don't get inspected as frequently as locomotives do. They only require comprehensive inspections every couple of years.
Before departure from a yard consists are supposed to be inspected by the car department but that doesn't require any special facilities, just a car knocker with a good pair of boots.
All of this is wonderfully explained in detail in The Model Railroader's Guide to Freight Cars by Jeff Wilson.
~BS
We're throwing around a lot of terms here, too....inspections, servicing and repair. lets make it clear that these are NOT all one and the same.
The RIP track is for just that, Repair-In-Place. Also known as the quick and dirty repairs made to a car in order to get it compliant and back out the door as quick and cheap as possible. This can include wheelset changes, brake change-outs, and safety-dependant equipment, such as grabs and ladders. Typically, but not always, cars in the RIP are from a non-home road...not to say home-road cars go elsewhere, it's just typically cars that end up in the RIP are cars that have arrived from elsewhere damaged and need to be repaired while en route.
Inspections, as Brian pointed out, are few and far between in the literal sense of the word. Freight car inspections, unlike that of a locomotive, are much less frequent...happening every few _years_, rather than the 92-days required of a locomotive. At least in theory, every time a car is humped, sorted, classed, cut or picked, it'll be inspected. Thats one of the many duties of the conductor, as well as that of the yard's Carmen. However, thats not to say cars get frequent nor through inspections in every yard. far from it, really.
The third term would be servicing...a freight car might be serviced in the RIP, but only if repairs were needed. It's not like a log is kept of the car and, at every X-thousand-miles, a light comes on and says "RIP and Service car XYZ at first available location". The car gets serviced when it needs it, when it gets damaged, or when it's every-couple-year inspection comes up...which ever of the three occurs first.
I suggest you get the Wilson book Brian mentioned above...Its a wonderful resource not only for the information you want now, but it could prove useful in the future, should you want to know more about freight cars.
AR
Got it. Read it. I don't recall all that much about servicing in it. I'll look again. It has been wonderful for helping me to figure out that I can't use most of the available N scale freight cars unless I do some serious modifications.
Yeah the en-route inspection is typically a couple of carmen walking (or driving) down the length of a train. One of the papers I found on freight car servicing dealt with how often needed repairs are missed - and how the author's machine vision algorithm can improve on that.
I wasn't real clear in my last post. This isn't a journal paper or dissertation, so I didn't go into depth about all the zigs and zags I did to get what I got. I found aggregated car maintenance cost and fleet status data, relative frequencies of various things to be fixed, average dwell times of cars in various yards and in RIP, and relative capacities of yards, RIP and car shops. There are just enough relationships between these data-points to figure out about how often a car goes to RIP for minor repairs, the car shop for major repairs, used for spare parts, or just stored as not worth the cost to fix. There appear to be accounting implications to scrapping cars, so the RR tries real hard not to just scrap cars.
How often do freight cars need servicing, as in set out to the RIP tracks? Or I suppose the better way to ask this is what percent of cars coming through a busy flat classification yard need to be set out for RIP? Or where can I find out?
I am guessing that it is more frequent for earlier eras, especially with journal bearings instead of roller bearing trucks. But beyond that I am clueless.
You're interested in the present era? If your plans are for a modern classification/hump yard, at what point would a "minor repair" be differentiated from a "major repair"? At a large modern yard, a protocol would dictate which was more economical - the car being moved to the car shop, or the carmen coming to the car.
The trainmen(if more than a 2 man crew) would inform their Conductor of the defective car. He would inform the Yardmaster, who would call the Mechanical Dept. The foreman in the car shop would make the decision.
If the needed repair was so minor that the car men could do it in place, the car would simply be set out on the nearest convenient track which had a vacancy and access from one side or the other. The yardmaster would assign that track - no need for a designated RIP track.
Unit trains, coal trains specifically, have scheduled maintenance for blocks of cars. Each return trip, "X" number of empties are pulled from the train, replaced by just serviced cars. Here are aerials of two BNSF facilities:
David,
I would be interested in the final outcome you end up with if just out of curiosity sake. My modeling will be old stuff and something like the small yard belonging to the Cumberland & Pennsylvania railroad in Mt Savage, MD (a small coal railroad in Allegany County, long gone and 100 years of steam before WM acquired them). I have already learned a bunch from this thread.
Thanks,
Charles
Sootower - I am trying to model 1946-47, but I am starting to think that I might want to move that to at least the early 50's due to rolling stock availability. Ever notice how every streamliner set includes dome observation cars? I can't use them in 1946. Not to mention not being able to use PS-1 boxcars.
This paper has some answers, and lots of interesting information on how things are done. According to a Kansas City Southern represenative about 10% of cars arriving in Knoche Yard (K.C., Mo) go to RIP. The hard data show 15-20 cars per day, with a few days each month exceeding that.
Each car spends 40-54 hours from the time it is bad-ordered until it is back in classification. Knoche is a flat yard.
Just tabulated the daily data from the paper. Since the number of cars inspected per day is highly variable, I divided the bad-order by number inspected for each day to give a percentage of bad-orders.
The mean daily percentage is 6.169% bad-ordered, with a standard deviation (population) of 3.514%. The histogram looks like it is a normal distribution, with a caveat about less than 0%.
For interests sake, on Nov 8, 1998 47 of 190 cars inspected were bad-ordered, or 24.7%. The most bad-ordered on a single day was 58. The fewest for a single day was 2. Knoche Yard only has room for 15 cars in RIP.
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