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Track gauge of Washington Metro 4' 8 1/4"--why?

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  • Member since
    December, 2007
  • 1,046 posts
Posted by Falcon48 on Saturday, June 24, 2017 12:26 AM

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.

 

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. 

  • Member since
    July, 2017
  • 2 posts
Posted by BackupBob on Wednesday, July 05, 2017 10:58 AM

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.  

 

 

 

  • Member since
    July, 2006
  • 6 posts
Posted by CADDguy on Monday, July 31, 2017 6:52 PM

I worked on MARTA with many BART veterans.  I understood that the wider BART gauge was to increase stability due to high coastal winds.

  • Member since
    May, 2004
  • 3,875 posts
Posted by 7j43k on Monday, July 31, 2017 7:15 PM

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

 

  • Member since
    May, 2013
  • 2,834 posts
Posted by NorthWest on Monday, July 31, 2017 7:19 PM

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.

  • Member since
    May, 2004
  • 3,875 posts
Posted by 7j43k on Monday, July 31, 2017 7:50 PM

 

  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

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