ORNHOOGetting back to speed limits...How do railroads determine the proper speed limit for a stretch of track, and especially the different speed limits for passenger and freight equipment? Around here (Columbia River Gorge) UP and BNSF speed limit signs usually show only a 5-10MPH difference (65/60 or 50/40 or such like). On the Portland and Western tracks used by Tri-Met's Eestside Express Service 60/40 signs can be seen. On the Caltrain line some signs (like the one by Sunnyvale station) show 79/45
What FRA level the track is maintained to will determine maximum allowable speed. The degree of curvature and the super-elevation that are built into the curves will determine the maximum allowable speeds through the curves. The carriers do no have to set different speeds between freight and passenger, though most do on their 'Main Line' subdivisions.
Never too old to have a happy childhood!
The speed is set at minimum by the FRA in 49CFR213.9 and can be further reduced downward by the carrier in their design calculations according to their curve design speed calculation in 49CFR213.57.... There is not a single class 1 railroad (or most of the smaller common carrier railroads) that uses the maximum allowable unbalance elevation of 3" in their calculation, most use between 1.75" and 2.25" as a design cushion for safety reasons. (operating department officials & their shiny toys be damned)
The difference for freight and passenger speeds is the fairly uniform center of gravity for passenger cars versus the "all over the place" center of gravity (and weight) of freight cars.
Ahem, from FRA's Rules of Centripital Force:
(a) The maximum elevation of the outside rail of a curve may not be more than 8 inches on track Classes 1 and 2, and 7 inches on track Classes 3 through 5. The outside rail of a curve may not be lower than the inside rail by design, except when engineered to address specific track or operating conditions; the limits in §213.63 apply in all cases.
(b) The maximum allowable posted timetable operating speed for each curve is determined by the following formula—
Where—
Vmax = Maximum allowable posted timetable operating speed (m.p.h.).
Ea = Actual elevation of the outside rail (inches).1
1Actual elevation, Ea, for each 155-foot track segment in the body of the curve is determined by averaging the elevation for 11 points through the segment at 15.5-foot spacing. If the curve length is less than 155 feet, the points are averaged through the full length of the body of the curve.
Eu = Qualified cant deficiency2 (inches) of the vehicle type.
2If the actual elevation, Ea, and degree of curvature, D, change as a result of track degradation, then the actual cant deficiency for the maximum allowable posted timetable operating speed, Vmax, may be greater than the qualified cant deficiency, Eu. This actual cant deficiency for each curve may not exceed the qualified cant deficiency, Eu, plus 1 inch.
D = Degree of curvature (degrees).3
3Degree of curvature, D, is determined by averaging the degree of curvature over the same track segment as the elevation.
(c) All vehicles are considered qualified for operating on track with a cant deficiency, Eu, not exceeding 3 inches. Table 1 of appendix A to this part is a table of speeds computed in accordance with the formula in paragraph (b) of this section, when Eu equals 3 inches, for various elevations and degrees of curvature.
(d) Each vehicle type must be approved by FRA to operate on track with a qualified cant deficiency, Eu, greater than 3 inches. Each vehicle type must demonstrate, in a ready-for-service load condition, compliance with the requirements of either paragraph (d)(1) or (2) of this section.
(1) When positioned on a track with a uniform superelevation equal to the proposed cant deficiency:
(i) No wheel of the vehicle type unloads to a value less than 60 percent of its static value on perfectly level track; and
(ii) For passenger cars, the roll angle between the floor of the equipment and the horizontal does not exceed 8.6 degrees; or
(2) When operating through a constant radius curve at a constant speed corresponding to the proposed cant deficiency, and a test plan is submitted to and approved by FRA in accordance with §213.345(e) and (f):
(i) The steady-state (average) load on any wheel, throughout the body of the curve, is not less than 60 percent of its static value on perfectly level track; and
(ii) For passenger cars, the steady-state (average) lateral acceleration measured on the floor of the carbody does not exceed 0.15g.
(e) The track owner or railroad shall transmit the results of the testing specified in paragraph (d) of this section to FRA's Associate Administrator for Railroad Safety/Chief Safety Officer (FRA) requesting approval for the vehicle type to operate at the desired curving speeds allowed under the formula in paragraph (b) of this section. The request shall be made in writing and contain, at a minimum, the following information—
(1) A description of the vehicle type involved, including schematic diagrams of the suspension system(s) and the estimated location of the center of gravity above top of rail;
(2) The test procedure,4 including the load condition under which the testing was performed, and description of the instrumentation used to qualify the vehicle type, as well as the maximum values for wheel unloading and roll angles or accelerations that were observed during testing; and
4The test procedure may be conducted whereby all the wheels on one side (right or left) of the vehicle are raised to the proposed cant deficiency, the vertical wheel loads under each wheel are measured, and a level is used to record the angle through which the floor of the vehicle has been rotated.
(3) For vehicle types not subject to parts 229 or 238 of this chapter, procedures or standards in effect that relate to the maintenance of all safety-critical components of the suspension system(s) for the particular vehicle type. Safety-critical components of the suspension system are those that impact or have significant influence on the roll of the carbody and the distribution of weight on the wheels.
(f) In approving the request made pursuant to paragraph (e) of this section, FRA may impose conditions necessary for safely operating at the higher curving speeds. Upon FRA approval of the request, the track owner or railroad shall notify FRA in writing no less than 30 calendar days prior to the proposed implementation of the approved higher curving speeds allowed under the formula in paragraph (b) of this section. The notification shall contain, at a minimum, identification of the track segment(s) on which the higher curving speeds are to be implemented.
(g) The documents required by this section must be provided to FRA by:
(1) The track owner; or
(2) A railroad that provides service with the same vehicle type over trackage of one or more track owner(s), with the written consent of each affected track owner.
(h)(1) Vehicle types permitted by FRA to operate at cant deficiencies, Eu, greater than 3 inches but not more than 5 inches shall be considered qualified under this section to operate at those permitted cant deficiencies for any track segment. The track owner or railroad shall notify FRA in writing no less than 30 calendar days prior to the proposed implementation of such curving speeds in accordance with paragraph (f) of this section.
(2) Vehicle types permitted by FRA to operate at cant deficiencies, Eu, greater than 5 inches shall be considered qualified under this section to operate at those permitted cant deficiencies only for the previously operated or identified track segments(s).
(i) For vehicle types intended to operate at any curving speed producing more than 5 inches of cant deficiency, the following provisions of subpart G of this part shall apply: §§213.333(a) through (g), (j)(1), (k) and (m), 213.345, and 213.369(f).
(j) As used in this section—
(1) Vehicle means a locomotive, as defined in §229.5 of this chapter; a freight car, as defined in §215.5 of this chapter; a passenger car, as defined in §238.5 of this chapter; and any rail rolling equipment used in a train with either a freight car or a passenger car.
(2) Vehicle type means like vehicles with variations in their physical properties, such as suspension, mass, interior arrangements, and dimensions that do not result in significant changes to their dynamic characteristics.
[78 FR 16101, Mar. 13, 2013]
(a) If a curve is elevated, the full elevation shall be provided throughout the curve, unless physical conditions do not permit. If elevation runoff occurs in a curve, the actual minimum elevation shall be used in computing the maximum allowable posted timetable operating speed for that curve under §213.57(b).
(b) Elevation runoff shall be at a uniform rate, within the limits of track surface deviation prescribed in §213.63, and it shall extend at least the full length of the spirals. If physical conditions do not permit a spiral long enough to accommodate the minimum length of runoff, part of the runoff may be on tangent track.
[63 FR 34029, June 22, 1998, as amended at 78 FR 16101, Mar. 13, 2013]
...and of course, you are going no faster than 49MPH if there is no track signal system in place.
wanswheel My grandfather was a fireman on the CV a hundred years ago, and a retired engineer when he called his suitcase his grip in the 1950s. It seems traveling salesmen called their bags their grips as well.
Mike, thanks for the picture; now all of us should have an idea of the size and shape of a valise.
Johnny
I keep thinking of "awol bag." Has anybody else here heard of it? Wikipedia says it doesn't exist. Maybe it was just an army thing. As I recall, it was similar to Johnny's valise, but the top spine under the handle was curved and the cross-section was more triangular.
EDIT: I just tried Bing and Google searches and came up with a great variety of shapes and styles. The term must have been more general than I thought.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Or RON kit ... Remain OverNight .
I think AWOL is a little more severe :)
zugmannDo you have one of those metal-ish boxes? One conductor I worked with had one, and his engineer referred to it as his "boxcar".
Yep. It certainly isn't made for everyday railroading - mine has already had some repairs, and I'm only on three days a week, if that. Were it not for the lantern, I could probably survive with a smaller version.
Odds are I'll go with something cloth when I replace this one.
One term that hasn't come up here yet is a "go bag." Kinda like an AWOL bag - packed with the basics for 72 hours in case of deployment. I don't keep one as such, but that's pretty much how I pack for my three day trips to work on the RR.
A go bag for disaster preparedness is something everyone should consider. Here's one take on it: http://www1.nyc.gov/site/em/ready/gather-supplies.page
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Mudchicken's post is about how to figure the maximum speed on any given curve, which is necessary, but I think it makes more sense to look at it the other way which is: How do I set up my speed zones for fastest possible time over the road consistent with safety and with reasonable fuel economy? This last point recognizes that speeding up and slowing down consumes fuel, time, and brake shoes. You should also keep in the back of your mind that when most of the rail lines now in service were built, 25 MPH was a typical actual speed. That made curves of 5 or 6 degrees non restricting and up to 10 degrees tollerable, that is OK for 25 MPH. Some lines built to such standards have been realligned to broaden curves, some have not.
First question is: What speed do I need and what can I afford from an investment and track maintenace cost point of view. If I have a reasonably short branch line there may be no need for freight train speeds over 25 MPH, which is FRA class II track, 40 MPH is class III, 60 is Class IV and 80 is Class V. In addition, if I want to go over 49 MPH I have to have signals. Speed costs money in terms of curves, grades, track manintenace, and signals.
If we decide that 60 MPH is fast enough, we need to determine how sharp a curve will force a speed restriction, and what the restriction will be. That is where the forumula comes in. My recollection is that it is about 4 degrees.
For curves under 4 degrees I use the formula to decide how much superelevation is needed in each curve at my intended speed. In fact I probably make up a chart of speed vs. curvature for roadmasters and tamper-liner operators. They also have track charts that show degree of curvature for each curve and max speed. The Great Northern used to have a sign on the outside of each curve that showed among other things the superelevation the engineers in St. Paul determined was appropriate for each curve.
In the case of a speed restricting curve, again we use the formula to determine maximum speed at a given amount of overballance. As MC mentioned each railroad may use something less than maximum overballance in this calculation. The reason is that at balance speed both rails are loaded equally. If the train is going slower than a design speed that includes overbalance, the low rail is overloaded, if it is going faster the high rail is overloaded.
Over the past 50 years the trend has been to lesser superelevation and to consolidation of speed restrictions since the performance of passenger trains, in my opinion, means a lot less than it did 50 years ago. Two examples.
The Great Northern line over Stevens Pass is built on 2.2%, compensated, ruling grade with a few 10 degree curves, and many not as sharp. In 1965 the line was posted for 25 MPH and curves were superelevated for that speed. Ascending freight trains could attain about 12-15 MPH, so they always overloaded the low rail. Passenger trains and descending freights could make 25 MPH and I suspect that the superelevation was based on ballance speed, not overballance. The reason is that designing with an overbalance would overload the low rail at the posted speed AND exagerate the overload on the low rail that ascending freight trains unavoidably put on it, all tending to drive the ties under the low rail into the subballast and creating a worse overbalance situation. Today the line is posted for 20 MPH and nobody cares that it takes ATK a few minutes more to travel through the pass than the real Empire Builder used to.
Another example. Both the GN and NP approach their respective Cascade Mountain passes from Puget Sound on lines with up to 1% ruling grades. Passenger trains could consistently make 60-70 MPH on the straight stretches. The GN had few restricting curves and I suspect the schedule was based on about 60 MPH runing.
The NP was not as well engineered in that it had many curves posted for about 35 MPH. The NP had a longer line than the GN did between St. Paul and Seattle, so to make time the NP engineers had to run right to the limit of 70-75 MPH almost everywhere. My recollection is that the subdivision limit was 70 MPH. I rode the passenger trains with my uncle, and even as an igrorant kid it was obvious that the NP guys were either in run 8 trying to get up to 70, or burning up the brakes to get down to 35 for the next curve. This had to burn more fuel than the GN's generally 60 MPH cruise.
Now bring that NP line forward to today for freight service when trains are at least a mile long and remember that the curve limit applies to the entire train. I suspect that long stretches are now posted for the 35 MPH curves, since there is neither running room or reason to ping-pong the speed.
Mac McCulloch
mudchickenThere is not a single class 1 railroad (or most of the smaller common carrier railroads) that uses the maximum allowable unbalance elevation of 3" in their calculation
Are all corner generally elevated on the outside track, or just those lines with higher speeds?
Thanks to Chris / CopCarSS for my avatar.
All mainline track curves generally have spirals and cross level of at least an inch. (Maximum of about 5"; 6" in the bad old days)
All industry track, yard track crossovers and turnouts are generally flat. Passing sidings are speed dependent. Sometimes the rail is given some elevation (inch or less) just to avoid adverse elevation. (FRA no-no)
Track machinery does not know how to go from tangent to curve without adding a spiral to the transition. (Nature of the beast)
timz mudchicken There is not a single class 1 railroad (or most of the smaller common carrier railroads) that uses the maximum allowable unbalance elevation of 3" in their calculation For freight trains, he means.
mudchicken There is not a single class 1 railroad (or most of the smaller common carrier railroads) that uses the maximum allowable unbalance elevation of 3" in their calculation
For freight trains, he means.
Grandma making fish-faces pressed-up against the window in the lounge car as it goes around the curve isn't a good thing either.
If they want to go slower, fine by us. Can we drop the cross-level so the shiny toys don't eat up the low rail?
zugmann Do you have one of those metal-ish boxes? One conductor I worked with had one, and his engineer referred to it as his "boxcar". I guess in the olden days, there were some RRers that would make metal grips to sell to other RRers. But those days are long past. [snipped - PDN]
I guess in the olden days, there were some RRers that would make metal grips to sell to other RRers. But those days are long past. [snipped - PDN]
EDIT: Do a search for "Fisher's Metal Cabin Grips" - you'll likely find them the subject of ads in 1918- 1920's Brotherhood magazines, in Google.books results. They were made by John C. Fisher & Co. in Freedom, PA - about 25 miles NW of Pittsburgh - i.e., deep in PRR territory. Plus, any PRR fan will know that "cabin" is PRR-speak for "caboose", where I suppose they could also be found.
- Paul North.
P.S. - Love the photo of "Grip Cat" !!! One of ours used to do the same thing to my flat leather briefcase, and the reference books on top of it. - PDN.
From what I understand, there were a couple guys that made the metal grips. Back when many people still had such mechanical skills, I guess.
They're still called cabin cars. Only weird people call them anything else, like caboose. (kidding...kidding...)
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
How much does a metal grip weigh? I hope it comes with a 2 wheel cart.Little red cabin car? No, sorry. That just doesn't sound right.
zugmann They're still called cabin cars. Only weird people call them anything else, like caboose. (kidding...kidding...)
Are you talking about waycars?
There are also speed restrictions due to equipment type and tons per operative brake. There can also be restrictions due to train placement errors. Loss of the capability to initiate an emergency application on the EOT limits a train to 30mph.
You can have 70 mph track, but trains for various reasons limited to less than that.
Jeff
With longstanding traditions in the past of sons following their fathers into railroad service, was it common gor a grip to be passed down to the next generation? If it's any consolation, I have my father's Brown Swiss milk crates.
jeffhergert[snipped - PDN} . . . One of our engineers likes to help out conductors by making sure they have an extra knuckle pin in their grip. One guy went a couple trips before he realized it was a bit heavier than normal. Jeff
Paul_D_North_Jr jeffhergert [snipped - PDN} . . . One of our engineers likes to help out conductors by making sure they have an extra knuckle pin in their grip. One guy went a couple trips before he realized it was a bit heavier than normal. Jeff In the winter, does that same engineer also turn on the air conditioning in another locomotive ? You know, to make sure it'll work strongly enough in the summer ? (I used to work with a guy who did that to our survey crews' vans while they were warming up, and the crew was inside for a job assignment, getting the survey equipment, supplies, coffee, etc.). - Paul North.
jeffhergert [snipped - PDN} . . . One of our engineers likes to help out conductors by making sure they have an extra knuckle pin in their grip. One guy went a couple trips before he realized it was a bit heavier than normal. Jeff
In the winter, does that same engineer also turn on the air conditioning in another locomotive ? You know, to make sure it'll work strongly enough in the summer ? (I used to work with a guy who did that to our survey crews' vans while they were warming up, and the crew was inside for a job assignment, getting the survey equipment, supplies, coffee, etc.).
No, but one afternoon we went around his train. As we passed the engine we noticed that it was a full "moon" that day.
jeffhergert Paul_D_North_Jr jeffhergert [snipped - PDN} . . . One of our engineers likes to help out conductors by making sure they have an extra knuckle pin in their grip. One guy went a couple trips before he realized it was a bit heavier than normal. Jeff In the winter, does that same engineer also turn on the air conditioning in another locomotive ? You know, to make sure it'll work strongly enough in the summer ? (I used to work with a guy who did that to our survey crews' vans while they were warming up, and the crew was inside for a job assignment, getting the survey equipment, supplies, coffee, etc.). No, but one afternoon we went around his train. As we passed the engine we noticed that it was a full "moon" that day.
Paul_D_North_Jr jeffhergert [snipped - PDN} . . . One of our engineers likes to help out conductors by making sure they have an extra knuckle pin in their grip. One guy went a couple trips before he realized it was a bit heavier than normal. Jeff In the winter, does that same engineer also turn on the air conditioning in another locomotive ? You know, to make sure it'll work strongly enough in the summer ? (I used to work with a guy who did that to our survey crews' vans while they were warming up, and the crew was inside for a job assignment, getting the survey equipment, supplies, coffee, etc.).
Ah,where are the peashooters and potato guns when opportunity shows itself?
And then there were briefcases, attaches, portmanteaus and Gladstones.
C&NW, CA&E, MILW, CGW and IC fan
Looks like wanswheel went back to the future last night ..
mudchickenAll mainline track curves generally have spirals and cross level of at least an inch. (Maximum of about 5"; 6" in the bad old days)
Made the trip from Thendara to Tupper Lake by rail yesterday for an equipment move. Many curves on the line (currently OOS) are still at their NYC cant - which was set for around 50 MPH. I was running the hi-rail dump truck, and there were a few times when I wondered about our stability, as I knew we were essentially riding on the lower side hi-rail wheels.
tree68 mudchicken All mainline track curves generally have spirals and cross level of at least an inch. (Maximum of about 5"; 6" in the bad old days) Made the trip from Thendara to Tupper Lake by rail yesterday for an equipment move. Many curves on the line (currently OOS) are still at their NYC cant - which was set for around 50 MPH. I was running the hi-rail dump truck, and there were a few times when I wondered about our stability, as I knew we were essentially riding on the lower side hi-rail wheels.
mudchicken All mainline track curves generally have spirals and cross level of at least an inch. (Maximum of about 5"; 6" in the bad old days)
rdamon Looks like wanswheel went back to the future last night ..
http://theoldmotor.com/?p=103058
The 130th Street curve on the CWI was superelevated for the benefit of the handful of passenger trains (Lake Cities, Thoroughbred, et. al.) that operated over that route. After two derailments involving intermodal equipment and the discontinuance of the Lake Cities, the curves were regraded with a lesser superelevation.
mudchickenThere are two curves on the East side of La Junta set up for 90 MPH and 5 1/2 inch crosslevel
Plenty ... but putting the carrots to those old horses to get to that speed coming out of yard limits is another story. The WB passenger trains get more out of those elevated curves than the other direction. The brake shoe folks have a source of constant income though....
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