Rail Physics & Track Class Science Discussion

[KEN PATRICK]

Edit by Charlie: I'm just Going to change the topic title to what "gokeefe" was shooting for and add his first post into this as a quote.

This thread is being opened in order to continue a discussion begun in the Oil Trains thread of the Pan Am Railways forum regarding the science behind the Federal Railroad Administration's specifications for Track Classes and the physics of track structure and rail-wheel interface.

what/who determines track speeds? can it be sort of a security blanket approach of the bureacratic fra or some risk-adverse railroad person? having looked at lots of track over 20 years and dealt with railroad track inspectors , i remain in the dark on empirical evidence leading to track speeds. what i do know however is that all railroads average only 22 mph flow-thru. this includes all facets of railroading. i remain incredulous that, notwithstanding billions invested in infrastructure, our nation remains hobbled by miserable freight throughput. now before anyone accuses me of negativity with no solutions offered, i point out a simple investment that would greatly improve speeds. ep braking. ep brake systems have been around for years but remain underutilized. the aar should edict all new railcars have ep braking and old within a 2 year window.i offered this to ns on a coal move using our cars over saluda mountain. ns rejected it because they would have to add in-cab controllers in designated power. i offered to pay for the controllers ( about 20k per ) ns again rejected since they couldn't guarantee the correct power. i opined they should just paint an x on the power. ken patrick

[KSmitty]

Track Speeds are based on FRA Track Class. The FRA standards for track classes, from Excepted (5mph running) to class 8 or is it 9(?) (North East Corridor speeds) are set by the FRA. The railroad looks at the requirements, and decides what level of track best balances traffic levels, and line production, with cost of maintenance. The railroad then establishes a section of track as a set class and maintains it to that level. The FRA then routinely sends their track cars around the US and checks to make sure the track is maintained to the standards. If the standards aren't being met then the FRA imposes slow orders and the railroad has 2 choices, repair the track to meet the standards or lower the track class to bring the track into compliance one way or another.

So in short, the railroad sets the speed and the FRA enforces it.

As for EP Braking, I assume you mean Electronically Controlled Pnuematic braking?
Granted I'm not an expert on the subject, but from what I've read ECP requires every car on a train to be so equipped. Meaning it would require massive investment in a very short time to convert the entire North American car fleet to make ECP available for general service.

And Power Control at NS would know what locomotives were so equipped without the X, computers do a wonderful job tracking equipment...The problem for NS would be asset management. If one of the so equipped locomotives goes down, they would need to replace it. When it comes back up it would need to go back into that dedicated service. That means keeping extra ECP equipped units parked incase 1 goes down, and since its all or nothing with ECP the reserve ECP units are wasting away. ECP certainly has its benefits, I agree with you 100% here, however its implementation is complicated and expensive. It would require massive investment and the creation of a uniform system that would be the standard and so work with all other ECP components on all railroads.

Edit* Also, slow average speeds are nothing new to railroading, but railroads have made strides in the way of IM, which is generally one of the few time sensitive components of railroading. Railroads long ago lost carload freight, and today don't really care to gain it back. Railroads are machines built to move massive amounts of bulk commodities, stuff that is relatively time insensitive...

[newpylong]

It is perplexing that you have dealt with track inspectors and not know this...

The FRA has pre-determined guidelines for classes of track - tie spacing, gauge distance, roadbad conditions, elevation, curvature, inspection schedule, etc and so on. The railroad takes the cost of maintaining and inspecting a section of track to all of these standards when determining maximum authorized speed. If the track inspector feels there is a sufficient defect, he puts a temporary speed restriction on it.

Pneumatic brakes would have minimal effect on train speed in this country. Do you actually think that track classes are set by the amount of time it takes to stop? The railroads don't care if it takes 3 miles or 300 feet to stop, the track is still only good for X mph.

FYI there is only one Class I RR in North America to average 22 mph and that is CSX. As another Eastern railroad NS not suprisingly comes in second close to 24 mph. The Canadian railroads, KCS and the Western Class I's are 26 mph+. Data from railroadpm.org for 2012. It makes no sense to average shortlines or regionals into this as they would never have the money or density to compete with the Class Is.

what/who determines track speeds? can it be sort of a security blanket approach of the bureacratic fra or some risk-adverse railroad person? having looked at lots of track over 20 years and dealt with railroad track inspectors , i remain in the dark on empirical evidence leading to track speeds. what i do know however is that all railroads average only 22 mph flow-thru. this includes all facets of railroading. i remain incredulous that, notwithstanding billions invested in infrastructure, our nation remains hobbled by miserable freight throughput. now before anyone accuses me of negativity with no solutions offered, i point out a simple investment that would greatly improve speeds. ep braking. ep brake systems have been around for years but remain underutilized. the aar should edict all new railcars have ep braking and old within a 2 year window.i offered this to ns on a coal move using our cars over saluda mountain. ns rejected it because they would have to add in-cab controllers in designated power. i offered to pay for the controllers ( about 20k per ) ns again rejected since they couldn't guarantee the correct power. i opined they should just paint an x on the power. ken patrick

[newpylong]

KSmitty FYI FRA Excepted track has a maximum authorized speed of 10 mph but more importantly is governed by restricted speed and about 10 guidelines/restrictions that it must fall under to be considered.

[KSmitty]

Thanks for the correction newpy. I, at one point, had the FRA spreadsheet that went over classes, max speeds for freight/passenger and the requirements that went with it all, but I cant find the pdf anymore...

[newpylong]

This one works: http://tacnet.missouri.org/history/railroads/fra.html

Enjoy some light reading, haha.

[KSmitty]

This one works: http://tacnet.missouri.org/history/railroads/fra.html

Enjoy some light reading, haha.

Thanks!

[markhb]

It is perplexing that you have dealt with track inspectors and not know this...

The FRA has pre-determined guidelines for classes of track - tie spacing, gauge distance, roadbad conditions, elevation, curvature, inspection schedule, etc and so on. The railroad takes the cost of maintaining and inspecting a section of track to all of these standards when determining maximum authorized speed. If the track inspector feels there is a sufficient defect, he puts a temporary speed restriction on it.

I'm going to give Ken the benefit of the doubt based on my reading of the sentence I highlighted in his quote below, particularly his reference to "empirical evidence." My impression is, he's wondering what studies/tests/mathematics underlie the calculation that <set of criteria that define a given track class X> => <maximum allowable speed Y>, or if the speed limits themselves are simply numbers that a set of Washington bureaucrats pulled out from between their glutes.

FYI there is only one Class I RR in North America to average 22 mph and that is CSX. As another Eastern railroad NS not suprisingly comes in second close to 24 mph. The Canadian railroads, KCS and the Western Class I's are 26 mph+. Data from railroadpm.org for 2012. It makes no sense to average shortlines or regionals into this as they would never have the money or density to compete with the Class Is.

I think, though, that whatever Ken may have folded into his "22 mph" figure, the RPM data doesn't tell the full story, at least not in a truly relevant form. We may know the average speed of the Class I's as they roll across the Plains, but I think the rock-bottom most important stat would instead be the average speed of a shipment from initial acceptance by a given railroad to disposition either to the ultimate consignee, to another road via interchange, or to another carrier via intermodal, with dwell time in terminals and yards included in the "hours" part of the mph calculation. Really, <rail distance -- or even great circle distance -- between consignor and consignee> / <wall clock time between acceptance by the originating road from the consignor and delivery to the consignee>. Ignoring Class II and III roads as part of the comparison doesn't really do us a lot of good, as in some or many cases (such as PAR), the smaller roads are providing "last mile(s)" coverage to get the shipment to its final destination, and their speeds definitely affect the overall "speed of shipment" calculation.

what/who determines track speeds? can it be sort of a security blanket approach of the bureacratic fra or some risk-adverse railroad person? having looked at lots of track over 20 years and dealt with railroad track inspectors , i remain in the dark on empirical evidence leading to track speeds. what i do know however is that all railroads average only 22 mph flow-thru. this includes all facets of railroading. i remain incredulous that, notwithstanding billions invested in infrastructure, our nation remains hobbled by miserable freight throughput... ken patrick

[newpylong]

If he is wondering what exact theorems are used in determining track classes by the FRA that certainly isn't something that is going to be discovered here...

As for average shipping speeds from door to door theorized to be so slow on average, sure, they are slow. That is why railroads are cheaper to ship with than trucks. I don't think we would would be winning the Darwin award for that conjecture, haha.

Can we get back to discussing the Oil trains?

[KEN PATRICK]

newpylong et al- i thought track speed was a proper discussion for this subject. if par raised it's track speeds, then it would enjoy increased profits from increased oil trains. whose to say that raising track speeds by 10%-20% from a subjective number exponentially increases likelihood of derailment ? are 3 good ties per 40' of track ok for what speeds ,is 70" too wide for 35mph. can i move at 20mph on 80#? i'm guessing the fra car is really looking for splits, not good v bad ties. i remain convinced that many 'standards' are folklore. ep brake valves -ep60- and wiring costs the same as present valve/slack adjusters and rods. train handling benefits yield quick payback. the train handling precision would permit oil trains to safely operate on subjectively graded track at higher speeds without impact cars, buff and drag dynamics and braking delay. i would hope that the new tank build would incorporate ep braking . leasing companies should take the lead on this. ken patrick

[KSmitty]

newpylong et al- i thought track speed was a proper discussion for this subject. if par raised it's track speeds, then it would enjoy increased profits from increased oil trains.

No doubt increased speeds would help the profit margin on these trains and make better crew useage possible. However, there is no more oil business to be had at this time. Maybe you've not noticed that the deliveries are far outstripping the refinery's abilities to unload the cars. They are taking close to 5 trains/week. Add in the MM&A oil and NBSR is taxed heavily, remember PAR's service is only as good as NBSR's. NBSR is just as strapped for crews as PAR.

whose to say that raising track speeds by 10%-20% from a subjective number exponentially increases likelihood of derailment ? are 3 good ties per 40' of track ok for what speeds ,is 70" too wide for 35mph. can i move at 20mph on 80#? i'm guessing the fra car is really looking for splits, not good v bad ties. i remain convinced that many 'standards' are folklore.

This is what the FRA is looking for, they measure gauge, they monitor track. These 'standards' are STANDARDS they aren't 'folklore' they are listed on the link provided earlier and they are enforced. The FRA commonly comes in and puts slow orders on. True the cars might not be looking at ties specifically, but its amazing how much difference in gauge you get when you have crappy ties. They do check the gauge, they check for cracks. You know whats amazing though, is how much the gauge doesn't change when the ties suck. Oh, wait, ties are the base and when they're bad everything else is noticably bad. So its safe to assume that bad ties lead to bad gauge which gets picked up by the FRA car. In addition they do visual inspections and DO check ties. The whole idea is that the track is held to standards for its class.

ep brake valves -ep60- and wiring costs the same as present valve/slack adjusters and rods. train handling benefits yield quick payback. the train handling precision would permit oil trains to safely operate on subjectively graded track at higher speeds without impact cars, buff and drag dynamics and braking delay. i would hope that the new tank build would incorporate ep braking . leasing companies should take the lead on this. ken patrick

As I said, EP was/is an "all or nothing" thing. Its use on a large scale would require insane amounts of initial investment because the entire NA rail fleet (locomotives and cars) would need to be outfitted. I don't know if you do any modeling, but if so think of it as going from Hook and Horn to knuckle couplers. Yes the end result looks good, but EVERY piece of equipment has to be converted essentially at once to keep everything compatable. The initial expense would be insane, and thats why no one has done more than dabble in ECP. And costs the same? Really? Prove that, because in addition to the pnuematic equipment you also need the electrical and computer components. Seems like a lot more expense, especially given the expense of wire these days.
Also, would it kill you to Capitalize words at the beginning of sentences. Not only are your posts generally rambling and unfounded but they extremely hard to read. A paragraph for each point and a Capitol at the beginning of each sentence would really improve your presentation, some people might even take you seriously...

[Cowford]

Distributed power provides braking benefits comparable to ECP, along with improved train handling... aside from cost/compatability issues, the diminished benefit with the use of DP is why you ain't seeing it.

[BigLou80]

ep brake valves -ep60- and wiring costs the same as present valve/slack adjusters and rods. train handling benefits yield quick payback. the train handling precision would permit oil trains to safely operate on subjectively graded track at higher speeds without impact cars, buff and drag dynamics and braking delay. i would hope that the new tank build would incorporate ep braking . leasing companies should take the lead on this. ken patrick

As I said, EP was/is an "all or nothing" thing. Its use on a large scale would require insane amounts of initial investment because the entire NA rail fleet (locomotives and cars) would need to be outfitted. I don't know if you do any modeling, but if so think of it as going from Hook and Horn to knuckle couplers. Yes the end result looks good, but EVERY piece of equipment has to be converted essentially at once to keep everything compatable. The initial expense would be insane, and thats why no one has done more than dabble in ECP. And costs the same? Really? Prove that, because in addition to the pnuematic equipment you also need the electrical and computer components. Seems like a lot more expense, especially given the expense of wire these days.

I am not so sure it's an all or nothing thing, I do believe it's possible to both overlay and retrofit. I think ken is probably right that it's not to much extra $$ to incorporate these on all new car builds and some leasing companies are missing a real opportunity here with so many unit trains, Dynamic brake proportioning has been a reality in cars for years. If nothing else all new car builds should at least include provisions to make the change over easy should their owner decide to do it. Again the auto industry has been doing that for years, look under the hood of you car there may be electrical connectors for sensors or devices that didn't become standard for another 2 model years. All that being said haven't we heard this whole we can't afford a better braking system thing from the rail roads before?

[gokeefe]

whose to say that raising track speeds by 10%-20% from a subjective number exponentially increases likelihood of derailment ? are 3 good ties per 40' of track ok for what speeds ,is 70" too wide for 35mph. can i move at 20mph on 80#? i'm guessing the fra car is really looking for splits, not good v bad ties. i remain convinced that many 'standards' are folklore.

Partly in honor of my Grandfather, John A. O'Keefe, III, who was a career government scientist with NASA I present the following reply:

If he is wondering what exact theorems are used in determining track classes by the FRA that certainly isn't something that is going to be discovered here...

Hm..funny you should mention this (I found it last night....):

From our friends at the National Transportation Library:

USDOT-FRA-ORD (Office of Research and Development), "Analytical Descriptions of Track Geometry Variations"

USDOT-FRA-TTC (Transportation Technology Center, Pueblo, CO) "Slab Track Test and Demonstration for Shared Freight and High Speed Passenger Service"

USDOT-FRA-ORD "Bridge Approaches and Track Stiffness"

USDOT-RITA (Research and Innovative Technology Administration) Volpe National Transportation Systems Center (VNTSC), "Estimating Track Capacity Based on Rail Stresses and Metal Fatigue"

USDOT-RITA-VNTSC, USDOT-FRA-ORD, "Estimation of Rail Wear Limits Based on Rail Strength Investigations"

USDOT-FRA-ORD "Statistical Representations of Track Geometry, Volume II, Appendices" (See Appendix G for a detailed narrative of research based on track analysis and the theorems used to understand and map track profiles)

And since I found it, here for posterity is the specification sheet for DOTX 219, the FRA's primary vehicle for the "Automated Track Inspection Program" (ATIP).

Given the legions of government scientists that conduct such painstaking research that is deeply grounded in the laws of physics and often driven by fatalities in real world operations I find the assertion that these safety standards are drawn from a "subjective" point of view to be particular galling.

In a more serious time and a more serious era the man whose obituaries are linked at the top was able to convince others using science that it was unnecessary to build weapons of killing power even more immense than anything ever built at that time or since then.

Science and safety are serious things. Government scientists can and do create real data that can save lives in applications both global and local. I summarily refute any assertion to the contrary.

Can we get back to discussing the Oil trains?

Most certainly. Reflecting on the capacity challenges presented by the Oil Trains once again led me to think of, yet another, bridge with an unused portion of highly strategic rail. This one over Back Cove in Portland.

My thoughts as follows: Short of double tracking through Portland I have to wonder just exactly how much capacity PAR has to run through Portland from Rigby. The single track section seems sufficiently short that perhaps extension of double tracking into North Deering could reduce any call or need for double tracking through the Woodford's neighborhood, but again, I have to wonder.

I'm quite sure that at current levels it wouldn't be necessary but I'm sure at some point, especially if the Downeaster goes north on a more frequent basis there could easily be a situation where it would make a lot of sense to send the train north of Portland via the MDOT/SLR instead of the rather crowded tracks through Deering to Royal Junction. After all we are not talking about ten times more traffic for this scenario to materialize. I would imagine that as little as 2x-3x more traffic would probably bring about congestion on PAR in that area sufficient to cause near constant disruption.

[EDIT: Added additional links, corrected errors]

[gokeefe]

Also "in honor of":

I submit the following:

L/V=(tanδ-μ)/(1+μ.tanδ)

Described as the "Nadal Limit" in this paper, USDOT-RITA-VNTSC, "Application of Nadal Limit in the Prediction of Wheel Climb Derailment".

Of significance the paper simply says that using known variables of L, lateral load, V, vertical load and μ, where μ is the coefficient of friction (which is proportional to the "speed" or velocity of the object) then one can reliably predict at what point wheel climb will likely occur.

Theorems such as the above are the fundamental basis for the track class limits that we have in place (still) today. Q.E.D.