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.
If anyone knew I figured David would know!
Yes, the former Alton that is being upgraded by ATK.
Actually it’s being upgraded at IDOTs expense by UP forces.
Ugh! I guess they thought a large fleet of cars would be enough to smear the equipment design costs out.
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.
Hey Feltonhill, you’re back! Don’t stay away so long! Lady Firestorm says “hi” as well!
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
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!!
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…
Absolutely correct. FRA rules for general system railroads permit a minimum 4’ 8" gauge up to Class 8 track (160 mph) and 4’ 8 1/4" for Class 9 track (220 mph). see 49 CFR 213.307(a) and 2113,323(b) Obviously, 1/4" narrow gauge is not a problem.
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
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 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.
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 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