Again, I'm not an engineer, so I don't know for sure what the explanation is for why the corrugation would be less in locations where trains regularly brake. One reason, I suppose, is that the suspension system may not be as free to move during braking. There is also an energy transfer going on during braking between the train and the rails, which may have some effect on the wheel-rail dynamics. Whatever the reason, something must be happening during braking that reduces the corrugation.
By the way, I live in the Chicago area and the CTA rapid transit has had the same problem, although it's not as bad today as it used to be. But it was really bad when CTA used PCC 'L' cars that didn't have much sound insulation and had open windows in warm weather. CTA, at one point, touted a special rail grinding train called the Sh-h-h-hicago as a solution to this problem. It did make the track quieter. But it also showered the track and surrounding neighborhoods with red hot grinding residue that started fires, so it was quietly retired. The CTA trains were also much quieter in areas (particularly approaching stations) where trains regularly braked.
With respect to the comment suggesting that non-tapered wheels might be more susceptible to derailment than tapered wheels, that was definitely not true of the North Shore Line, which used non-tapered wheels for decades in high speed service. The very reason they used this design was to reduce the chances of derailment by reducing the severe truck hunting they were experiencing with traditional tapered wheels. Also, I don't know whether this is true, but I've been told that CTA still uses non-tapered wheels.
7j43k Paul of Covington Speaking of wheel slip-- with zero taper on the wheels you are depending solely on the flanges to keep you on the track, so would it be advantageous to have the wheels free to turn independently on the axles? This way you are not forcing the wheels to slip on the curves. I'm not sure, but I seem to remember reading that Talgo (or maybe it was somebody else) wheels are designed that way. You "can't" because the wheels are powered. They are driven by only one traction motor per axle. You would then need two motors per axle. Which is certainly possible, and maybe even a great idea. But I don't think anyone's done it. Hey. Maybe I invented it. Dibs! You would also need, I think, really good motor controllers, so as to keep the two motors appropriately matched. Ed
Paul of Covington Speaking of wheel slip-- with zero taper on the wheels you are depending solely on the flanges to keep you on the track, so would it be advantageous to have the wheels free to turn independently on the axles? This way you are not forcing the wheels to slip on the curves. I'm not sure, but I seem to remember reading that Talgo (or maybe it was somebody else) wheels are designed that way.
Speaking of wheel slip-- with zero taper on the wheels you are depending solely on the flanges to keep you on the track, so would it be advantageous to have the wheels free to turn independently on the axles? This way you are not forcing the wheels to slip on the curves. I'm not sure, but I seem to remember reading that Talgo (or maybe it was somebody else) wheels are designed that way.
You "can't" because the wheels are powered. They are driven by only one traction motor per axle. You would then need two motors per axle. Which is certainly possible, and maybe even a great idea. But I don't think anyone's done it.
Hey. Maybe I invented it.
Dibs!
You would also need, I think, really good motor controllers, so as to keep the two motors appropriately matched.
Ed
Thanks, Ed. I didn't realize that all wheels were powered. I should have thought, "subway", rather than "train". I suppose you could rig an automobile style differential, but that would add weight and complication plus a little loss to friction. Oh well.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Falcon48 Again, I'm not an engineer, so I can't give definitive answers. But let me speculate a little. I suspect that rail corrugation on transit systems like BART is primarily caused by the relatively light loading on the wheels, which leads to uneven loading as the trains run over the track at speed.
Again, I'm not an engineer, so I can't give definitive answers. But let me speculate a little.
I suspect that rail corrugation on transit systems like BART is primarily caused by the relatively light loading on the wheels, which leads to uneven loading as the trains run over the track at speed.
I don't follow your reasoning. If you're saying the problem would be solved by adding some concrete under the floor to correct for the light loading, my thought is that the suspension system was not properly designed in the first place. So it should be corrected.
Once an uneven wear pattern starts to develop, passing trains will gradually make it worse.
Fer shure!
This would explain why there seems to be less corrugation in areas where trains regularly brake. The braking would tend to put more weight on the wheels.
I don't see how. The train weighs what it weighs. There is no spare weight that somehow gets put on the wheels. You COULD argue weight transfer. That is also something that should be corrected by redesign of the suspension. There would also be a reverse weight transfer on acceleration. And that would negate your observation, I think.
However. If the problem shows less where there is regular braking, it could be because that is also where the motors are accelerating less, as in "not". Which gets me thinking of uneven torque at the railhead causing slipping. And wear. The uneven torque would most likely be caused by the motor poles, as mentioned earlier. If this is the cause, one solution is slower acceleration from a stop. Another might be using sand on acceleration, to raise the coefficient of friction. Still another might be better motor control.
I suspect that rail corrugation on transit systems like BART is primarily caused by the relatively light loading on the wheels, which leads to uneven loading as the trains run over the track at speed. Once an uneven wear pattern starts to develop, passing trains will gradually make it worse. This would explain why there seems to be less corrugation in areas where trains regularly brake. The braking would tend to put more weight on the wheels. Keep in mind that we're not talking about deep ridges or anything like that - it's more like a very shallow undulation. But steel wheels running over irregularities like this at speed will be very noisy (particularly on unballasted track).
I agree with you that, on BART, corrugation is probably not the source of most of the noise on curves. As you say, the source is probably differential wheel slip - particularly on sharp, lower speed curves where the wheel slip would be the greatest. That would be more of an issue with BART than with other transit systems with similar curvature because BART is wide gauge, so the slip would be greater on BART. That said, I seem to recall in riding BART that, not only is there curve noise or sharp curves, but also a feeling that the wheels are bumping over something. I'm just speculating, but I suspect this is due to deeper corrugation caused by repeated wheel slippage in the same spots.
So my first impression about rail corrugation was the correct one, eh.
I wonder what causes it. The spacing of the repeat should tell something. I wonder what the distance is. And also where the problem happens, and how badly. All that should be revealing and useful.
For example: perhaps it is caused by the spacing of the poles of the motors. If so, then there would be a predicatable spacing of corrugations.
There is also truck hunting caused by the non-tapered treads. This should show up on straight track. Hunting is much more difficult or impossible on curves, since the wheels are shoved outwards towards their flanges. I wonder what the predicted spacing would be with that as a cause.
I found a link to illustrations that showed BART was louder on curves:
https://www.atsconsulting.com/rail-corrugation-at-bart
They seem to think the noise is caused by corrugation. The noise is louder on curves--is the corrugation worse on curves?
To me, the problem being louder in curves would appear to be caused by differential wheel slip caused by the use of non-tapered tread. That problem should be lessened by going to tapered treads. I wonder what it will do for the straight sections.
Well, I'd sure like to know what the NAS analyzed, and what values they got for other transit systems. It may be that, on non-corrugated track segments, or on ballasted track, BART is quieter than late 19th and early 20th century steel 'L' structures. But I've ridden BART many times, and the noise on portions of BART (primarily on track on the elevated structures and in tunnels) is earsplitting - much worse than any other modern rapid transit lines I've ridden.
With respect to corrugation, rail corrugation is, in fact, a "cross rail" condition. It is a series of seemingly small irregularities across the railhead a few inches apart. You can see them (particularly on the really bad segments), but you have to know what you're looking for. Viewed from above, they usually don't look like ridges - rather they look like narrow shadows an inch or so wide across the railhead. While they are small, they set up a very loud vibration whe wheels pass over them at speed. The solution is to regularly grind the rail to restore the rail profile. This condition also develops on regular railroads and is, again, addressed by periodic grinding. I suspect that BART isn't grinding the rails regularly enough to control this problem
The wheel "taper" issue certainly would affect noise on curves and the sharper the curve is the worse it would be (primarily due to wheel slippage as mentioned by 7j43k). I suppose it could also cause more corrugation on curves as well, if the wheels are slipping in the same place all the time. But this wouldn't afffect corrugation on relatively straight track where there's no wheel slippage.
I don't know for sure the reason BART originally adopted the "non-tapered" wheel profile, but I suspect it had to do with concerns about truck "hunting" with lightweight, high speed transit equipment. At the time it was built, BART was one of the fastest (if not the fastest) rapid transit lines in the U.S. Truck hunting was a known issue on high speed electric lines since the 1920's. The North Shore Line in Chicago, in particular, had severe truck hunting issues on the high speed segments of their railroad (they discovered the problem by hanging a camera under a high speed car). They solved it by going to non-tapered wheels, which they used for the rest of their existence. Presumably, BART has now concluded that this isn't a serious issue on their system.
Falcon48 BART is VERY loud - much louder than other "modern" rapid transit lines I've used. It often gets earsplitting on the trains (actually painful), so I can only imagine what it's like for those who live near the tracks.
I'm not an engineer, but my take is that much of the noise is being caused by severe rail corrugation which is not effectively managed. It's so bad, you can actually see the corrugation ridges in many places. When you ride, notice that the noise level isn't constant, and it's always loudest in the same spots. Also, as I recall, it gets more quiet where trains regularly brake (probably because the braking changes the rail-wheel dynamics in those areas. reducing the corrugation).
When I first read this, I thought that it meant that there were regularly spaced bumps in the rail surface--that the grooves and bumps had a cross-rail axis. Further reading on the subject showed that the grooves run parallel to the rail axis.
The problem seems to be especially bad on curves, both the grooving and the noise. Apparently, BART decided to have their wheels produced with zero tread taper. What this means is that, when going around curves, the correction to wheel diameters that the taper gives does not happen. And there is consequent slippage of the wheels. This causes extra noise in the curves, and extra wear. BART, after long and careful study, has decided to change the tread taper to what most of the rest of the United States (world?) uses.
How long did it take BART to come to this conclusion? It sounds like BART has been running straight-taper wheels since the beginning, 1972. Of course, it would take a few years for the downside to develop, say 5. So, the answer would appear to be about 40 years. Looks like they were afraid of appearing impetuous and/or flighty.
[quote user="7j43k"]
Paul of Covington I keep hearing about property values going up because of HSR. This may be true near stations, but HSR stops would be very few and far between, otherwise it wouldn't be very high speed. What happens to property values near the ROW with no stations nearby?
I keep hearing about property values going up because of HSR. This may be true near stations, but HSR stops would be very few and far between, otherwise it wouldn't be very high speed. What happens to property values near the ROW with no stations nearby?
Most of the ROW will be at grade or raised up on towers. We have, locally, an existing example to study.
If your property is near overhead BART tracks, values would likely be downward. The noise of each train passing is awful. And it can be heard for a goodly distance. I don't see how anyone can sleep. Also, it's not quite the visual treat you might think; although that doesn't radiate beyond the first layer or two of residences.
But this all only applies to populated areas. And the central valley is full of farmers, and who cares about them?
Berkeley required BART to be inderground as it passes through the city. And I believe the city paid for the extra cost. Thus, aside from the added cost, I doubt values were impacted. Maybe during construction, but that's years ago. Now.
Pretty impressive for the Berkeley City Council.
Falcon48
Checking Rentjungle(dot)com reveals quite a few units offered in the $1500-1900/month range as well, many of them listed as "newly refurbished"
Hey, if somebody thinks they can skirt the system by working in a community where the average income is $119K/yr, while living in a quonset hut out in the high desert, more power to them, but why should they get a subsidized commute as well?
Everyone knows Castro Valley isn't in the East Bay. It's the gateway city to "out there". Sorta like Orinda.
I haven't seen a lot of house tear-downs in any of those places. But then, I don't GO to any of those places.
Hayward's $2157 a month. And the apartment you get is a palatial 816 sq ft. So you only have to bring in $12 an hour after witholding. What will you do with all that extra money? Oh. I know: Food.........
7j43kSo, yes, you'll save $1000 a month living in Oakland.
Have they torn down all the houses in Hayward, Union City, and Castro Valley?
Average rent for Oakland is (from online) $2624. For 697 sq ft.
For SF, $3772 (no size stated).
So, yes, you'll save $1000 a month living in Oakland.
These are not houses where you have a family. These are apartments. Guess what you pay for a house where you want to raise your children.
If we divide $2624 by 180 (working hours in one month) we get $14.58 and hour. You will have to make that AFTER witholding to just pay the rent. No utilities. No food. No car. No nuthin'.
Welcome back!
During the 3 years that I lived in the Bay area, I found rents in the east bay to be dramatically cheaper than on the peninsula,this was true for residential, commercial, and industrial. So much so that many firms that historically have been considered "San Francisco organizations" have their bay area presence in the East bay. So I don't see the more extreme examples of these "cost of living" dramas to be particularly relevant. Even if I HAD to work in the SF CBD, I would not commute 100+ miles per day, knowing there were alternatives
Convicted One Of course one of the beauties of prop 13 is that it protects corporate land owners in addition to single homesteads.
Of course one of the beauties of prop 13 is that it protects corporate land owners in addition to single homesteads.
It was poorly written. I am sure the Legislature could have done a better job, if they had bothered. Or wanted to. They didn't.
Voters wanted relief on property taxes. The Legislature didn't.
Convicted One 7j43k But this all only applies to populated areas. And the central valley is full of farmers, and who cares about them? While your "quality of living" points make perfect sense, I think that at least a portion of POC's question was an attempt to qualify that this forecast for new demand for highly valued residences along the HSR corridor, will be limited to dirt actually near a train station,...which will be a considerable distance apart.
7j43k But this all only applies to populated areas. And the central valley is full of farmers, and who cares about them?
While your "quality of living" points make perfect sense, I think that at least a portion of POC's question was an attempt to qualify that this forecast for new demand for highly valued residences along the HSR corridor, will be limited to dirt actually near a train station,...which will be a considerable distance apart.
I noticed that. But he asked about the in-between. I used BART as an example because their tower construction looks the same as the half mile of HSR structure that's already built.
I then said that the values of housing near those BART tracks were negatively affected by the sound and the visual, while potentially not being able to take advantage of the boost upwards of being near a station.
I then shifted over to HSR, and the "neighborhoods" it would go through. Much of that is farmland. At first, one could react with "and plants would care how?". But the farmers could also possibly live near the HSR trackage. And get no boost because there is no station. But also get to hear the noise. On the plus side, steers could use the towers to rub against; and a happy steer is, well, a happy steer.
And. The farm lobby does not look to me to be terribly impactful on California government these days.
Who cares about the farmers? I doubt that many who eat what the farmers produce even know that they exist.
Johnny
Of course one of the beauties of prop 13 is that it protects corporate land owners in addition to single homesteads. So these farmers along the HSR corridor could easily convert their use to high-end trailer parks and become land barons, property value locked in at 1976 valuations.
Seriously though, I wonder how many people out there might be working toward land re-zonings along the HSR corridors,... purely on spec?
7j43kBut this all only applies to populated areas. And the central valley is full of farmers, and who cares about them?
Looks like it.
I recall Danny DeVito's line in one of his movies. He kept using the term OPM. He explained that it meant "other people's money". And discussed the concept further.
7j43k. So, if YOU want to live in these newly wonderful places, you will be paying top dollar for your new house. And top dollar in property taxes, too.
So, this strategy is depenant upon a quantum shift following along the new opportunity, and not an automatic given?
Could happen,...could also not happen. At least to an extent that is guaranteed to be economically viable . I absolutely hate it when people think that it is the government's "job" to spend other people's money on them.
Convicted One 7j43k That's great. So the increased income from property taxes can go to pay for the very thing that caused that increase. And once paid off, it's all gravy. Didn't prop 13 lock in the valuation at 1976 levels, and cap the property tax at like 1%? (unless there is a change in ownership or substantial on site improvements)
7j43k That's great. So the increased income from property taxes can go to pay for the very thing that caused that increase. And once paid off, it's all gravy.
Didn't prop 13 lock in the valuation at 1976 levels, and cap the property tax at like 1%? (unless there is a change in ownership or substantial on site improvements)
Yes.
But when the HSR goes in, and living in these areas becomes more attractive (that IS the point of HSR, isn't it?), then prices for housing will go up. So, if YOU want to live in these newly wonderful places, you will be paying top dollar for your new house. And top dollar in property taxes, too.
Hence the "increased income from property taxes" I mentioned.
Or, of course, you could continue to live in your studio apartment in SF for $3500 a month. No, wait. It just went up.
It'll be great, I tell ya.
7j43kThat's great. So the increased income from property taxes can go to pay for the very thing that caused that increase. And once paid off, it's all gravy.
YoHo1975As was previously stated, if nothing else, HSR and an improved ability to move from the San Joaquin to the Silicon Valley is going to generate property tax increases at a minimum.
That's great. So the increased income from property taxes can go to pay for the very thing that caused that increase. And once paid off, it's all gravy.
It will also in fact impact cost of living in a positive way for the consumer.
It'll lower their cost of living? Great. Some of that extra money could go to higher fares for the train. Again, to pay it off.
That's a net benefit to the Federal government though the accounting is more challenging and isn't all in hard dollars.
The accounting certainly could be challenging, considering the feds don't get property taxes (the ones that increased). Because of that, perhaps the feds could cut back on the financial aid, since the state's local governments have experienced an increase in income.
The Federal Government isn't in the business of being revenue neutral much less turning a profit.
So true; so true. But there are other goverments in this country who are. And they somehow survive. Perhaps we should change the federal government to be more like them.
Else every single military item not actively in use would be sold or laid off.
By that reasoning, I should sell my tools every time I don't have any work, and buy new ones when I get some. I'm just not sure that's a good idea, for me or for the military.
Sinking money into something that provides social benefit or state level benefits that will eventually trickle back to the fed is a perfectly good use of tax dollars.
"Sinking money into..." and "...trickle back...". I do detect a difference in scale, there.
Now that I've been all negative, I'll say that I think it does make sense for governments to invest money into the future. I also believe that they should do their accounting. That means that the project really should turn a profit. Because that profit enables investing in still another project. As opposed to not. Because it's been spent.
[quote user="JPS1"]
1) The value of the bonds the government purchased to support the "Pacific" railroads was $64,000,000 at the time of purchase. 2) The amount repaid by the Pacifc railroads for the bonds, including interest , was $167,000,000, giving the government a profit of over $100,000,000.
1) The value of the bonds the government purchased to support the "Pacific" railroads was $64,000,000 at the time of purchase.
2) The amount repaid by the Pacifc railroads for the bonds, including interest , was $167,000,000, giving the government a profit of over $100,000,000.
What do the numbers look like after adjustment for inflation? Frequently, after adjusting for inflation, a seemingly significant gain melts away or is significantly reduced in real dollar terms.
I have no way of quantifying inflation or deflation during the period the bonds were outstanding. I recall from some other histories I've read that there were depressions in the late 1870's and early 1890's (the one starting in 1893 was particularly severe). Depressions are usually deflationary, but that doesn't account for the entire period.
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