Resonant Vibration in Railroad Tracks

I have not seen ground resonance mentioned locally as a cause for a derailment before, but it could be that it is due to our slower general speeds on Cape gauge track (1065mm or ±3'6") - we tend to top out at 100km/h section design speeds. There was an exercise in the 80's to run a suburban trainset at 160 km/h (I think) - I'm not sure what they experienced, but it was dropped (the exercise, not the train!).

There has been incidents of derailments caused by harmonic roll of wagons as described by one of the other posters, with wagons transporting liquids. It tended to happen where there are out of spec turnouts at yard or station loop exits, or a repetitive geometrical fault on the running lines that was not repaired in time. They can be quite disatrous. It is a form of resonance, but inside the wagon, not in the track or substructure. It is normally due to substandard maintenance & inspection issues, not design.

Thanks for posting a thought-provoking question!

There is no doubt that resonance can be very destructive.

Tesla nearly brought down a building in a nearby city using resonant frequency of the

building,and inserting the frequency into the ground.

Like a kid on a swing,instinctively knowing when to pull back on the ropes to get increased height.

If you wanted to create an earthquake at a certain location,send out a pulse,time it's echo,then synchronize the next pulse to coincide with that frequency.

The location of max force could be determined precisely by the echo.

Over time the energy would be additive and destructive.

Controlled demolition anyone?

I am surprised the military has not thought of this and used it.

OOPS!

Don't want to give them ideas.

Adds a whole new meaning to train surfing!

https://en.wikipedia.org/wiki/Train_surfing

It is a primary reason why passenger-carrying railways in the UK changed from 45ft rails to 60ft rails during the middle of the 20th Century. The reaction between 45ft rails and new stock with around 45ft between bogie centres was a thing to behold: the train galloped along like a race horse, shaking both the train and the track to pieces.

In the UK, the practice before welded rail became commonplace was to make the fishplate joints parallel. In North America the practice was to stagger them by half a rail length; the practice tended to set up side-to-side rocking in trains, exacerbated by part-filled tank wagons where the load sloshed from side to side in harmony at some speeds. Continuous-welded rail obviates this problem, however it does require a level of investment in upgrading that has been difficult to find on that continent, particularly in rural districts where the traffic is light.

It has been a practice in the US ,( regretttably not all track,) to replace bolted sections with welded rail, especially on main line trackage. I've worked on such projects where the sections were moved into place as 1 mile sections all at once. Most memorable thing about it was the mosquitoes!

Gah!

We need Rearden metal! Don't know what that is...ask John Galt!

I might be stealing your Heinlein quote : )

Drew K

Now that's a snowblower!

http://www.core77.com/posts/24370/Video-of-Snowblowing-Trains

Image 4: Whaddaya get when you cross a cowcatcher with a Cuisinart?

A billion served within a week!

white pass train in action.(built 1899) still in use today.

1985

1950's

2012

Here's a video of a train plowing through the snow.

That's awesome....

Maybe not the best place to sit on the fence

https://www.youtube.com/watch?v=-ugIoMD495E

Yes you are correct in that harmful vibrations are induced into the rails then transferred into the ties and earth below the rails.

We have several sites that utilize railroads for transporting materials and products on a large scale and we suffer the expense of derailments regularly.

We do employ staggered joint placement and stress absorbing structures in some locations where the incidence of derailment is high.

Most of the derailments that occur are due to:

1. Lack of, or poor/incorrect maintenance inspections.

2. Failure to maintain the metal spikes that hold the rails in place by utilizing the intensive manual labor required to tighten and re-spike the rails on a regular interval.

3. Failure to replace degraded and failed/broken wooden ties that have failed due to poor drainage and natural degradation from the sunlight which allow the spikes to become loose and or come out of the tie.

4. Failure to keep rail splice plate bolts tight and properly torqued.

5. Failure to properly maintain the rail switches at rail intersection locations and on spurs.

6. Failure to maintain rail level elevations by "lifting and tamping" of the rail ballast underneath the ties on the needed interval.

7. Failure to properly inspect and maintain railroad crossings.

8. Failure to identify and replace worn out and/or damaged rail.

All of the above mention conditions allow the rail to spread apart or rupture when subjected to loading stress.

Unfortunately management personnel of railroads simply are not willing to and do not spend the money to fund proper preventative maintenance until they are forced to do so.

Downright scary when you think about it considering what the trains are hauling, the speed they are traveling, and the risk to the general public and environment.

Now here is the modern way to replace old ties and rails.

AMAZING!

1 question:How often do they install an expansion joint?

https://www.youtube.com/watch?v=_MKcTbYDP7w

A thing of beauty is a joy forever. :-)

Great Post!

Other than the automatic tie tamper and leveling machine most of the railroads around here still do the work by hand.

Using concrete cement ties stop the issues caused by wood tie degradation and rotting but there aren't very many in use in my neck of the woods.

The automated machinery is extremely costly and apparently those in charge of making the decision to spend the money aren't willing to do so. (Yet)

Hopefully one of these days we will get into the 21st century with this subject.

Beautiful! PATH tried to place a cement base with cement ties in one of their tunnels. Of course they decided that the trial project would be the bottom of the grade - the most distant location possible. The concrete pump wouldn't pump, the work train skidded to the site with locked brakes due to condensation on the rails and then bridged the power sections and barely missed zapping several people. They gave up and placed gravel and wood ties to get it back in service before Monday rush hour. Most amazing fuster cluck I've ever seen!

That is a beautiful machine. Thanks Hitec.

Everybody sing now--John Henry was a rail-drivin' man!

Gotta hand it to whoever came up with the idea of steel tracks and flanged wheels was a genius.

Not many inventions have endured so long in the same basic form as railroad and tracks.

Well,except maybe the wheel itself.

Powering of the engines has advanced,but only minor modifications of the basic design.

The earliest raised rails (as opposed to grooves in stone) were made of wood, finding a use for moving ore out of mines. The location of the carriage on the track was assured by pins pointing down between the rails. The flanged wheel came much later.
There is a technical museum in Berlin where visitors can try pushing wagons along a short wooden track. For the obsessive, there is another museum in Georgsmarienhütte, north Germany, devoted to illustrating different steel track sections.

One other thing not mentioned about derailments. Some freight cars will at certain speeds start harmonics which will cause the trucks to do excessive hunting. This will cause the wheels to lift off the rail head, and if they lift too much, stuff happens. Some trains with the known suspects, will have speed limits placed on them.

When the train is moving, car wheels would create vibration pulses to the individual sleeper. As it hits it with speed, this would generate a frequency directly proportional to the speed of car times the number of wheels of the cars it hits individual sleeper.

Sleepers are designed to isolate the vibration as the wheel passes by and as you see it is individually separated from one after another. With the ballast made out of gravel, it should be able to damp the vibration generated from every hit of the wheels each of them. Plus if rails are not welded continously, resonance wont be an issue, though it may have an impact on fasteners and small things with the same resonant frequency of the vibration the wheel has created.

High frequency vibration is easily exhausted with the ballast and easy to damp, unlike low frequency thingy. Bulky things likewise has low resonant frequency.

I would say, resonance will be an issue if train is running at low speed, with fewer wheels, ballastless tracks and continously welded rails.

The strangest thing I ever saw involving a train was an early 20th century train hauling timber from a swamp.

Men laid down long trees end to end,before laying the cross ties on top.

The train rocked from side to side,and end to end like a snake in ashes.

It was slow,but it stayed on the tracks.

Had to be a real hoot for the engineer.

When they needed to move deeper into the swamp,they manually moved the logs to create another section.

Of course,men worked really hard back in those days,like the men that felled the trees with axes,before the advent of chain saws.

Here is a tribute to days gone by;doesn't seem so long ago....

http://www.metrolyrics.com/city-of-new-orleans-lyrics-guthrie-arlo.html

https://www.youtube.com/watch?v=TvMS_ykiLiQ

I just thought of another issue that might add to the problem of tanker cars,and that is if they are not totally filled.

The sloshing of the oil could amplify the resonance on a local level,and all it takes is for one car to be at the top of the cycle,and the one behind on the bottom of the cycle.

This would make one car derail,and all it takes is one to trip all of the dominoes.

Highway tankers have compartments designed to minimize sloshing,but I have not seen anything similar on train tankers.

Any trucker that has ever hauled a tanker will tell you about the effect of sloshing when the brakes are applied.

I noticed that in most all of the tanker derailments, the first few cars stayed on the tracks,and the ones behind derailed;possibly due to a "whiplash" effect?

It's odd to call it "water hammer effect" when its actually oil right?

Harmonics could be a factor, but it could also be a case of track maintenance, or lack thereof, as the bean-counters try to get the most 'rent' out of a stretch of track between periods of costly, not-making-money-on-that-section railwork.

https://en.wikipedia.org/wiki/Track_(rail_transport)#maintenance

"Bean counters" are responsible for many disasters,including the Titanic.

They decided it was too expensive to carry the compartment walls all the way to the ceiling,because they thought"The water will never get that deep anyway."

Also, there were not enough lifeboats because of the flawed assumption that the ship was never going to sink anyway.

The same could be said about aircraft,buildings,bridges,etc.

Accountants have their function, but they should not delve into engineering matters.

If a question begins with "Why didn't they" or "Why did they" the answer is usually "Money."

And that is why Engineers and Accountants will always get along like the Montegues and Capulets (Or the Sharks and the Jets, if you prefer the Jazz-Tap Broadway version of the story).

The bean-counters second-guess our work, destroying our designs to 'save money,' when we designed things to 'save lives.' Can you really put a price tag on a human life?

Oh yeah, the bean-counters who work for insurance companies claim that they've already done that. Yeah, like you could just requisition a 'replacement human' like you're ordering a spare gasket seal.

Accountants think that if 1 ship can sail across the ocean in 10 days,then 2 ships can sail across in 5 days.

The numbers all add up on paper.

Management thinks that if you have 2 men on a job,you have one too many.

And remember:Figures don't lie. But liars can figure.

Engineers, or wanna be engineers, have caused far more disasters than bean counters. They compromised safety in the interest of cost. That is their job. The safest approach is the most costly, 99 times out of 100. The vast majority of the decisions are guided and feasible, thanks to the rigor of the profession and regulatory environment, but some are disastrous.

Bean counters pay engineers. Engineers want to get paid. There is a finite amount of pay available. Anyone who asks rhetorically, "how much is one life worth" has no understanding of how capitalism works. It is worth exactly how much someone will pay for it, no more, no less, just like everything else. Those of you who cry like giant babies when regulators act in the public's best interest might want to take note. They are inflating the value of your life.

That awesome rail machine that hitek posted is only used in socialist countries that have made the decision that life on the tracks is worth more than we think it is in the USA.

"Engineers, or wanna be engineers, have caused far more disasters than bean counters. "

Do you have any real statistics to back that up? I strongly suspect that it is easier for most bean counters to hide their mistakes than it is for most engineers.

In my limited experience, most bean counters are unable to understand and/or apply the engineering concepts required to make informed decisions.

"They compromised safety in the interest of cost. That is their job. The safest approach is the most costly, 99 times out of 100."

No..., that does not sound like an Engineer to me, that sounds like an Accountant. Are you sure you have your terms straight?

No engineer I know gets a blank checkbook to solve a problem. They are focused on meeting regulatory requirements, functional requirements and quality requirements (lifespan) while meeting time deadlines and budget. Blaming an engineering failure on an accountant? Congrats on a creative approach to CYA.

When the Engineer says, "We found this problem in the design, we can fix it, but it'll cost an additional $11 per car," and the accountant says "too expensive, we won't do it," who do you blame, the one who found a problem and came up with a solution, or the one who blocked the implementation of the solution?

Let's put it another way, Mr A sees a baby sitting in a sheet metal press, runs to hit the e-stop button, but Mr B grabs Mr A's arm, saying 'we can't afford the lost production.' Who do you blame for the flat baby?

HTR, although that is an interesting theory, I would more likely look at not enough money being spent on track and equipment maintenance as the most likely culprit. (not that you'll get the railroad to admit it)

Many people do not realize that all trains have a clutch.

!!

A clutch gradually applies the load to prevent stall of the prime mover.

This clutch is actually the designed hysteresis of the couplings between cars.

When a train is stopped,all of the slack is toward the front,and when the train begins

to move,each coupling applies load sequentially.

When a train slows down,the weight slowly shifts toward the front.

If all loads are the same weight there is a minimal problem.

If however,there are light loads,interspersed among the heavy loads,when the train begins to slow down, the heavier loads behind will tend to push the lighter ones in front.

This will make the lighter load slam into the one ahead as the hysteresis shifts forward.

If the lighter loads are between heavier loads, this can cause a wave to occur and "squeeze" out the middle car(s).

An ideal load would have all cars the same weight,or all lighter loads at the rear.

This is not feasible with regular freight,but with hundreds of tankers,filled with same product,it is important that all be of same weight.

This is a separate issue from the sloshing of partially filled tanks,which can become additive due to this wave-like transfer of force and hysteresis.

There are many factors that can set up unpredictable resonance in the ground or within the cars themselves.

There is no simple solution,but when you have to eat an elephant,you do it one bite at the time.

That's not all the hysteresis of the couplers can do.

When my father was working as an electrician for Ringling Bros. he told us stories about how the train drivers would get the mile-long circus train moving out of the yard.

1. The engine would be started in reverse briefly, to knock the first car backwards.
2. that would hit the second car, then the third, on down the line.
3. the last car would roll back to its limit.
4. at this moment, the train is stretched out to its maximum length, all the couplers are under tension.
5. the tension pulls the last car forward, until it hits the car in front of it, the energy wave the driver sent to the rear now reflected back to the front.
6. The driver starts moving forward just before the reflected wave hits the engine, using that energy for the extra 'oomph' to overcome the train's inertia and get things rolling.

I've heard this technique is also used on cargo trains, but not on passenger-only trains, as, depending on how long the train is, the last car can experience a one-two jerk that is anywhere from uncomfortable to practically neck-snapping. The reason they can use it on the Ringling Bros. train is due to the car layout. The back half of the train is all 'cargo,' the wagons, rigging, vehicles, etc., but not the lights⁽¹⁾. The middle of the train⁽²⁾ is where all the performers are kept, and the front of the train, the section that is the most 'luxurious,' the most 'comfortable' is reserved for the Animals, with the elephants in the prime cars right behind the engine⁽³⁾.

Notes:

1. The lighting NEVER travels by train, they're way too fragile. the lighting always travels over the road in Air-Ride trucks.
2. Technically the second quarter, or the 'back half of the front half,' but you get the idea.
3. The elephants get the choice spot because they could get hurt really bad if they fell over in the car. They ride sideways to the tracks, and they've got railings to lean against, but if one takes a tumble, she⁽⁴⁾ could knock her neighbor over and land on her legs. Elephant legs are strong, but they can't take the force of another elephant crashing down on them from the side.
4. It may be sexist, but Ringling does not take the bull elephants on the road, only the ladies and the children. The kids love to play and show off their talents⁽⁵⁾, and the ladies are all good team players. The men, however, can act like frat boys trying to get dates for the Homecoming dance, and that's just too much disruption when on tour⁽⁶⁾.
5. Yes, the 'painter elephant' is real, and she has total creative freedom. She chooses which color and when, where to put the paint, and when to say 'done.' She can even chose to not paint if she's not feeling inspired. However, she LOVES painting, you put a canvas in front of her and she'll go to town on it, even without the promise of a treat afterwards⁽⁷⁾.
6. That's not to say that the ladies are all perfect finishing school graduates, they often act like bored teenagers when backstage, pulling pranks and finding ways to amuse themselves. At one venue, there was an HVAC duct overhead above their 'green room,' everyone thought it was fine because it was high up. Every night, during the show, there was a mysterious banging sound echoing through the arena, but nobody could find the source. It turned out that one of the ladies was hopping on her neighbor, like in the 'long mount' line you usually see at the end of an elephant act, and from that vantage point, she could reach the duct with her trunk, and was banging on it like a drum. It took a while for them to be caught at it because the elephants by the door were acting as lookouts, letting the rest know when a person was coming so they could all 'act innocent' about the noise. Not only were they banging on a duct out of boredom, they also new it was wrong, and worked together to cover it up.
7. At Ringling, the elephants go nuts for their 'candy;' whole unsliced loves of white bread. I'm guessing it's a combination of the taste and the 'sugar rush' that hits a little while later. (The carbs in white bread are very simple, practically just two sugars tied together, really spikes the blood sugar level.)
   

The following came from a friend who is a retired railroader when I asked him about the thread. I doubt his 10 feet deep roadbed though.

It is possible but I doubt it. The roadbed under the tracks and ties is 10 ft. deep and is packed,tamped ballast. As to rail joints, on all of the Class 1 railroads that haul this stuff the track is welded rail, a joint only every 1/4 to 3/4 of a mile. The speed of haz-mat oil trains etc is limited to 30 mph. There are detectors every 10 miles to check wheels and bearings.

Back in the day when the over size box cars and auto transport cars were introduced we did have a thing called Dynamic Rock. It happened between 15 and 21 mph I believe. We were to slow down if we could not maintain mph between these speeds. The track back then was jointed, not welded as it is today.
It does seem to me that if a train derails and one haz-mat car is in the train, that is the one that will go in the ditch,

Gandy Dancers

And even now, rr's are still using this method even if in small repair sections. If those are typical crow-foot bars, they can pr4ovide as much as 20 tons of force. (yes, 20!)

"...they can pr4ovide (sic) as much as 20 tons of force."

Not if used as shown in the photo! A strong man in that position can pull up with a force of perhaps 300 pounds. The bars stuck down into the ballast as shown have at best a mechanical advantage of 10:1. 10*300=3000lb, or 1.5 tons.

For a man to exert a force of 20 tons, the mechanical advantage would have to be around 130. If the bars are 65" long, the distance from the fulcrum to the load would have to be about 0.5 inches. Provide an adequate fulcrum point, and the 20 ton force is indeed possible.

I'm a small man, but I have used a bar to move rocks weighing around 3 tons. To do that I had to work at obtaining appropriate fulcrum points, and of course each effort only moved the rock a few tenths of an inch. I also usually was moving only one side or end of the rock, thereby dividing the required force by roughly 2 (or roughly doubling the size of rock that could be moved).

I do agree with you, I was commenting on the bar itself as regards the force it can impose.

If either one of you (or anyone else for that matter) are in the area next spring, stop by on a track maintenance weekend and you can find out exactly how much force can be generated using one. Volunteers are always welcome for this and many other projects we have going. (two steam engines being restored to operational. Yea, we are ambitious)

http://www.midcontinent.org/

In the paper this morning the CN released that the derailment was caused by a broken rail. They claim it was a non-visible defect and that the track had been ultrasonically scanned back in September.

IMHO, Sounds like a case of CYA.

An ultrasonic scan, properly interpreted, would show impending failure via metal fatigue.

It doesn't happen overnight,or over 30 days for that matter on a well maintained track.

Now if there was a weak spot of support,in a relatively small section of the track,causing the track to flex excessively,and abnormally,then repetitive flexing could cause a sudden failure.

That would be revealed by signs of heat at the breakage point if it was suddenly flexed to the breaking point.

Like bending a paper clip till it breaks,it will get very hot at the flex point.

It will still eventually break if you make one bend per day,but it will not get hot.

If that was the case,the rail breakage was due a deeper underlying cause;shifted ballast,loose spikes,loose plates,etc.

Perhaps even a case of "Well,we can get one more month out of that before it fails,and time is money."

But of course,we know that would never happen in the real world.

I read somewhere, that for every passenger carried, there is at least one worker keeping the rr in good condition. That also helps to explain why cargo only tracks are never in the same condition.

...but it does not explain why cargo has the precedence over passenger trains in the USA. 20 years ago, I took a train from CA to NY and back via New Orleans. The train was already 5 hours late by the time I got to Colorado, due to waiting for cargo trains. I had planned the trip, among other things, specifically to see the Rockies from the train, but by the time we reached the Rockies, it was dark, and I could see absolutely nothing. That's why I haven't been on a train in 20 years, and don't expect to ever again.

Passengers are clearly not (unless things have changed drastically) a priority on the US rail system.

Actually it does. Passenger service is far more expensive to run. If the rr's had their way, there would be no passenger service. The only reason there is, is the feds mandate to run it and subsidize it. Passenger only service like the PATH system lose money despite the heavy use, and PATH is busy 24/7. Trains run every 2 minutes in rush hour and it takes determination to get on at the intermediate stations. It exists only because the Port Authority of NY & NJ subsidizes it. When it was taken over, back in the early 60's it was heavily in debt and still running (barely), with many delays caused by failing equipment. There was a display in the old Cortland St terminal (where the World Trade Center was later built) of a 500MCM cable that was down to about (guessing) 150MCM and still in service. It was finally removed when it actually failed under load.

Is it possible that commuter trains could provide urban employment access to thousands of people who don't have resources to purchase, register and insure autos, or who hope to avoid hours spent sitting on the congested roads breathing the exhaust of an overcrowded freeway, consuming fuel that is produced with significant environmental and geopolitical impact. Is there value there?

Maybe they want to participate in a social compact that contributes to intelligent resource management, or maybe it is just an affordable way to get to work or school. Highways are financed by citizens, and the operation of them looks unfathomable on a balance sheet, especially when you capitalize land and construction. Trucking companies may contribute to the success of the highway system through fuel taxes, but the existence of the industry would not be possible without the financial support of the taxpayers, and it is hard to imagine a scenario in which those taxes could finance the infrastructure. Highways are enormous money pits that grease the wheels. Passenger trains should enjoy the same subsidy, because they really work, they give me and bluebelly a clear sailing pass to drive when we want. For about the 1000th time, I submit that there are many things that capitalists are terrible at creating, and public transportation is one of them. Hospitals, grade schools and fire departments are a few more.