Somewhere in the distant past, I got the impression that passenger trains were limited to a total of 23 cars of all types.
My questions are:
(1) is this correct?
(2) is so, is it a function of the time it takes for the airbrake signal to reach all cars in emergency application, since seconds count in preventing accidents or train crew rules… so many cars monitored by a single conductor or trainman?
retired grouch in Jersey
I don’t recall any ‘rule mandated’ maximum passenger train length.
A 23 car passenger train would be approximately 2000 feet long, considering that prior to Amtrak and the reliance on Head End Power for heating and cooling of the cars, steam was the power for heating and in some cases cooling of passenger car, I would expect 2000 feet is about as far as you could maintain adequate steam pressure, considering the routine conditions of the steam lines on the equipment. In Zero style cold weather, even much shorter trains would have the steam lines freeze.
ATSF used to have a restriction of 18 cars on the “Super Chief/El Capitan” because of platform and grade crossing limitations at Topeka and perhaps other places. SCL and its predecessors may have operated longer Florida trains during the peak winter season, especially the “Florida Special”.
http://www.youtube.com/watch?v=ofVhMHua9hQ&feature=geosearch
Count the cars…
http://www.youtube.com/watch?v=j6XWdKZpkn0
I didn’t take these videos; I was on this 25 car train when they were taken.
Airbrakes work at apporximately the speed of sound. So while there is a delay in braking, it’s only a 100th of a second or so, and it’s by car usually, not length.
Now, what;s interesting, is that NS DOES have a policy that tells engineers to stop train longer than 21 0r 2300 feet with the dynamic, not the air. But I really don;t see Amtrak having trains too much longer than that to warrant a similar rule, (even with Priate Varnish added on) especially since I’m pretty sure there’s no dynamic on the P42s
How long was the UP “City of Everywhere” in the Sixties?
I also wonder about Amtrak’s California Zephyr/Pioneer/Desert Wind between Chicago and Salt Lake City in the eighties.
Both of those trains could have been pretty long.
My guess is that in today’s world with HEP the only really important thing is the length of the station platforms and even that can be dealt with if enough station dwell time is taken into consideration for several movements within the station to accomodate the longer train length. I’v personally seen Amtrak’s Empre Builder make one stop and two additional movements at the Columbus, WI station due to that station’s short platrorm.
VIA Rail Canada operated a train with 30 cars and 3 engines from Halifax to Montreal, a special for veterans heading to the November 11 2005 services in Ottawa.
There is an air brake issue with longer passenger trains. Passenger trains are typically operated with a “graduated release” feature. What this means is that the engineer, after making an air brake application, can make a partial (or “graduated” ) release of the brakes. This isn’t possible with a freight train. On a freight train, any release of the air brakes is a full release - the engineer has no ability to make a partial release. If you’re familiar with the locomotive brake valves, they have a "passenger " and “freight” setting. The difference is that the “passenger” setting will allow the engineer to make a “graduated release” (if the train is equipped for it), while the “freight” setting will not.
However, the “graduated release” feature becomes unusuable if the passenger train gets too long. I’m not sure what the critical length is, but at some point, the train gets so long that a graduated release will not be uniformally transmitted through the entire train (because the pressure change in the train line towards the rear of the train may be different than at the front of the train). In this case, the front of the train may partially release while the rear of the train stays fully applied, which causes undesireable train dynamics. There is a solution to this problem, which is to have the entire train set up to operate like a freight trai
The original Autotrain originally ran with the auto carriers in front of the pasenger cars and was about forty cars long or longer. Due to different type brakes on the two types of cars the variance in response time caused a couple of serious derailments. The last one was in 1976 and after that the auto careers were a separate train leaving before the passenger portion.
In another thread, I seem to recall an Amtrak employee telling us that 16 Superliners was the maximum number of cars that the HEP in a P42 could handle.
Train length is also governed by station platform considerations. Case in point. A few years ago I was fortunate enough to addend the APTA convention in Toronto. APTA would arrange a train tour the day before the convention opening and this tour was a trip to Niagara Falls. The train consisted of 15 GO Transit bilevel coaches. No problem loading in Toronto as the station is large (and currently being englarged). Niagara Falls was a different story. I think the station could almost fit into my garage. The platform only could handle three coaches at a time so the train was jogged letting three coaches unload at a time. I was in the last set of coaches and when getting off I looked down the track towards the engine. The engine and the first two coaches were across the international bridge and in the United States.
Every Amtrak train I ride only loads and unloads through a couple of doors anyway. When you walk through several cars to the door, the platform length becomes less important.
In the bygone days of railroad passenger operations, the passenger load would be aportioned to the cars by destination. ‘Shorts’ (those passengers not going to the ultimate destination of the train) would be seated in specific cars…those were the cars that would be stopped at the platform in small stations with small platform area. Needless to say the boarding passengers would also be seated (most likely) in the ‘short’ car(s). Full length platforms were rarely available at intermediate stations.
There were limits by railroad. I remember that my CB&Q rule books limited 6 ‘motors’ as the maximum MU for a passenger train. We once ran a combined TCZ/EB/NCL out of St Paul with 6 E’s and 32 cars(we had to double the train out of SPUD, and make double stops for station platforms. The next day the ‘summer’ schedule was introduced ‘early’ and we were running two sections.
Air brakes release at about 6-7 passenger cars/second. If the train is equiped with electro-numatic valves, one get get an instant release(CB&Q/NP cars were set-up with this, but NP did not use it most of the time. A long train might require the ‘freight’ setting due to propagation issues with the total train length. IIRC, Auto Train did this on their very long trains in the 70’s.
Jim
You just reminded me that the last time I took the Empire Builder to Minneapolis they seated us “shorts” in certain cars…this was done at Chicago Union Station and we were given certain colored “boarding passes” indicating which car we were to board.
It always seems to be hard for us fans to get the straight dope on how many cars a given engine can supply HEP to. Seems to me when Amtrak’s second order of F40s came out with 800 kW HEP that was claimed to be enough for 18 Superliners-- but does that assume the cars aren’t all at their maximum demand? In any case, I think 18-car Superliner trains (or maybe Superliner/HiLevel) did run as specials to Seahawks games circa 1980.
People have been known to claim ALP44s can only supply HEP to six of NJT’s bilevels. Sounds unlikely, but nobody seems to know what the cars actually do demand, or what the ALP can supply.
I asked my father about this in the early seventies and he said the “standard” was to have no more than 20 passenger occupied cars and the related baggage cars. Other head end cars didn’t figure into this.
This was because it was determined that at the biggest stations, the loading and unloading process of the passenger’s and their luggage would jam up the station hallways, stairways, and waiting rooms, if you used any more cars. Smaller stations dealt with capacity issues as mentioned above.
So a few years later when I was getting my accounting certificate at college, we had to take what is called queuing theory. The management of large numbers of people in small areas. Everybody had trouble with this class, but once the railway station idea was in my head, I sailed through that class.
I always found it interesting watching documentaries about passenger trains in countries like India, China and others, that the 20 car idea is surprisingly widespread.
When questions like this come up 35 years later, it still brings a smile to my face.
Bruce
Ahah! A prime example of logistics dictating reality. Thanks!!