I note that cars buses and trucks use that bridge, and wind problems are quite rare.
I would be interested in seeing BART's engineering research from the early days on this matter.
I have heard a number of reasons for the choice of track gage.
Ed
I think that the original plan was to send a line over the Golden Gate bridge, but due to funding issues with the North Bay counties it never happened.
I wonder what high coastal winds they're talking about. I've lived in the Bay Area since before BART was started, and it never particularly seemed windy to me.
I wonder why The Windy City doesn't have problems with their trains blowing over. Perhaps they do, and it doesn't make the news here in the Bay Area.
This does bring up the possiblity that San Francisco will have to take over Chicago's nickname.
I worked on MARTA with many BART veterans. I understood that the wider BART gauge was to increase stability due to high coastal winds.
I will try to address a number of issues that have been raised here.
Metro gauge is 1/4" narrower than usual but that does not stop railway cars from running on it. I have heard this had to do with the use of cylindrical wheels instead of conical wheels. Metro now uses conical wheels.
In 1976 the Brentwood Yard had a number of Korean War era flatcars delivered on railway flatcars. The parts for them were contained in three large boxcars. These cars were assembled and put to good use by the track department. They are moved by military surplus diesel locomotives, which have had their tops lowered such that you have to be Quasimodo to fit in the cab.
I was with ATC (signals) and prior to acceptance of the yard signals we had to switch trains manually. It is great fun riding the front end of a boxcar that is being pushed, waving flags while trying to avoid the steps on passing signal poles, which are located very close to the tracks.
Brentwood also handled the pairs of flatbed trailers that delivered the original 300 Rohr cars. The Sperry rail test car used to come in via the Brentwood interchange track, where it was dispatched to the rest of the railroad. One would think Metro would re-gauge the railroad as stretches of track or ties are replaced. With the recent "safe track" operations this would have been very possible but I don't know if was done.
Recently Metro has had a bigger problem than a 1/4" tight gauge. In several interlockings the gauge was wide enough that trains fell into a hole. How they can let a crossover remain in service with a 1-2" wide gauge defies belief.
The Safe Track operation required quite a bit of single tracking. This means that two emergency crossovers will be used heavily all day long for several days or weeks.
Common sense says that if a device that is little use will suddenly see heavy use that it should be inspected and possibly serviced as necessary prior to the start of the project. That was not done and last July at East Falls Church a revenue train crossing over found a hole in the rails and dropped a few cars on the ground. Interlocking inspections were not current and some inspection data may have been "fudged". A number of people were fired and others resigned.
A similar thing happened a year or so earlier at the Smithsonian interlocking when a train was crossing over prior to going into revenue service. It found a hole was almost 2" wide, one that had been flagged during an inspection over a month prior to the derailment. In my time at Metro you did not walk away from something like that until it was fixed or the track was taken out of service but things have changed since then.
The massive track repair effort known as "Safe Track" is over but there are still original ties dating back to 1975 at Brentwood Yard. Alexandria Yard is newer but it, too, has a lot of older ties. I wonder when they will be replaced.
bartman-tn 1/4" makes no real difference in the gage of a railroad. The track gage for railroads start with a minimum of 4' 8", and then have a maximum based upon the track class. Track classes 4 and 5 have a maximum gage of 4' 9-1/2", class 2 and 3 is 4' 9-3/4", and class 1 is 4' 10". As long as the gage is between the minimum and maximum, it is fine. Some railroads go with a slight narrower gage than the design gage (4' 8-1/2") to prevent wheel hunting. This can provide a slightly smoother ride if the alinement is correct.
1/4" makes no real difference in the gage of a railroad. The track gage for railroads start with a minimum of 4' 8", and then have a maximum based upon the track class. Track classes 4 and 5 have a maximum gage of 4' 9-1/2", class 2 and 3 is 4' 9-3/4", and class 1 is 4' 10". As long as the gage is between the minimum and maximum, it is fine.
Some railroads go with a slight narrower gage than the design gage (4' 8-1/2") to prevent wheel hunting. This can provide a slightly smoother ride if the alinement is correct.
feltonhill I worked for Metro's engineering consulting firm (DeLeuw Cather) in the late 1970s, and the reason of the gauge difference was to complement the cylindrical wheel profile used on the subway cars. They didn't have the conventional 1:20 or 1:40 taper. The tighter gauge would reduce the amount of truck "hunting" with this configuration. It seemed to work OK, but the cars were noisy going around sharp curves, and I don't mean flange squeal! There was a lower pitch sound that could have been caused by microslip of the inside wheels. Normal wheel taper takes care of this problem.
I worked for Metro's engineering consulting firm (DeLeuw Cather) in the late 1970s, and the reason of the gauge difference was to complement the cylindrical wheel profile used on the subway cars. They didn't have the conventional 1:20 or 1:40 taper. The tighter gauge would reduce the amount of truck "hunting" with this configuration. It seemed to work OK, but the cars were noisy going around sharp curves, and I don't mean flange squeal! There was a lower pitch sound that could have been caused by microslip of the inside wheels. Normal wheel taper takes care of this problem.
Wow. Great info! Cylindrical wheels for only 75 mph operation. I would have though 1:40 would be okay. The cars are long enough they shouldn't have had hunting problems...
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Firelock,
I've just been lurking more than contributing lately. The DC subway was one area that I had some first-hand experience that may help answer the initial question.
Thanks for noticing!!
I did find a discussion in railroad.net and someone said, The gauge broadens in curves slightly based on the radii.
Alittle more info if you go look. There was something about rail grinding.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Hey Feltonhill, you're back! Don't stay away so long! Lady Firestorm says "hi" as well!
daveklepper I can answer the last question. Lower tunnel height and less construction cost than has been standard for North American subways. Russ Jackson said: The cement pourers designed the cars. Lower floors also mean lower ceilings. The lower construction costs have meant higher equipment first costs and maintenance costs.
I can answer the last question. Lower tunnel height and less construction cost than has been standard for North American subways. Russ Jackson said:
The cement pourers designed the cars.
Lower floors also mean lower ceilings. The lower construction costs have meant higher equipment first costs and maintenance costs.
Ugh! I guess they thought a large fleet of cars would be enough to smear the equipment design costs out.
MidlandMike Deggesty CHI-STL is owned by UP, and they expressed the possibility of using the line more now that it is improved. You do refer to the former Alton and not the former C&EI-Big Four, do you not? Yes, the former Alton that is being upgraded by ATK.
Deggesty CHI-STL is owned by UP, and they expressed the possibility of using the line more now that it is improved. You do refer to the former Alton and not the former C&EI-Big Four, do you not?
CHI-STL is owned by UP, and they expressed the possibility of using the line more now that it is improved.
You do refer to the former Alton and not the former C&EI-Big Four, do you not?
Yes, the former Alton that is being upgraded by ATK.
Actually it's being upgraded at IDOTs expense by UP forces.
If anyone knew I figured David would know!
From a practical standpoint, you can still use standard axles and wheels, you'd just press them on a fraction more.
The real mystery question is why DC Metro didn't use standard platform height. It keeps them from buying industry standard undercar equipment.
The Joliet-Alton portion is owned by UP, the Chicago-Joliet portion is owned by CN, the Alton-St. Louis section may be TRRA trackage, I'm not sure about that. The jumbled ownership is fallout from the sale of that line by IC to Chicago, Missouri & Western.
MidlandMike blue streak 1 What are the guages for the NEC, NJT, MNRR, Albany, Michigan, CHI - STL ? Then what are the freight RRs doing ? CHI-STL is owned by UP, and they expressed the possibility of using the line more now that it is improved.
blue streak 1 What are the guages for the NEC, NJT, MNRR, Albany, Michigan, CHI - STL ? Then what are the freight RRs doing ?
What are the guages for the NEC, NJT, MNRR, Albany, Michigan, CHI - STL ?
Then what are the freight RRs doing ?
Johnny
Thank you, all, for you answers.
I was exposed many years ago to "gauge conspiracy", wherein non-standard track gauges are chose to limit interchangeability. In that early case, the reason BART chose wide gauge was to preclude any standard/typical rolling stock from using their trackage. True or not, I don't know. Just reporting what someone else firmly believed.
So I've been a bit sensitive to that possiblity ever since. Which thus came up as a possible explanation for the Metro 1/4" variation.
What appears to be the true reason for the Metro-quarter came to me after posting the question here--a little meditation time.
So I've had a chance to learn a little bit more about the workings of flanged wheels on rails. A VERY clever invention.
Thanks again,
Lab Just guessing also, but maybe it was so interchange rail cars would not fit.
Just guessing also, but maybe it was so interchange rail cars would not fit.
Zero percent chance of that. Why? Because Metro *did* have an interchange with the Southern in Alexandria during construction. The remains of connection are still there in the weeds and bushes, but long ago severed.
I don't know for a fact, but I'm reasonably sure The Great Society Subway would have an answer, if there even is one.
Cleveland RTA used MOW equipement that is interchanged with Norfolk Southern at there yard on E 55. The problem here with Pennsyvania Trolley Gauge and the Metro is how do you retrofit contract MOW maintace equipment?
The PRR used two track gauges depending on what was the primary traffic on that set of rails. For track that was heavily used by passenger trains the gauge of 4' 8 1/4" was used to give a smoother ride. For track that was primarily freight the gauge of 4' 9" was used to reduce friction.
So I expect that the Metro selected its gauge to give a smoother ride.
Remember that on well-maintained track with well-maintaned rolling-stock, the wheel taper is supposed to prevent hunting and prevent the flanges from scraping against the inside rail face. So the wheel gauge, between the flanges' outside faces adjoing the tread, has always been narrorer than the rail gauge. But the North Shore and some othe interurban and many transit properties used and use wheels with little or no taper. Be interesting to know what taper if any this system uses.
Back in the late 60's there were a few reports of RR's tightening track gauge to 4"8-1/4" as steam locomotives were no longer being operated. Claimed benefit was better riding as the gauge faces of the track were closer to the fillets on the wheel.
Two ideas, both probably wrong
Speculation1
With wear the track gage will widen overtime requiring regaging. In Railway Track and Maintenance by Tratman it says that widening by 1/4" on tangents and 1/2" on curves is acceptable before regaging is necessary. On 4'8-1/2 gage track reguaging would be need on tangents at 4'8-3/4"and curves at 4'9".
I doubt 4'8-1/4" gage would preclude the use of wheel components which could run on the widened standard gage. Perhaps by starting with a slightly narrower gage they increase the time interval between regaging.
Speculation2
The designers intended the system to be standard gage and goofed.
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
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