4 ms·

I'm surprised the article didn't mention that BART is the only train in North America on the uncommon 5'6" gauge. This is another factor making parts and equipm

I'm surprised the article didn't mention that BART is the only train in North America on the uncommon 5'6" gauge. This is another factor making parts and equipment more difficult to source.

djbusby 4y ago
It also makes the trains stable; wide stance.
- carlivar 4y ago
  Was it necessary to do that? A stability problem elsewhere?
  - fuckstick 4y ago
    https://www.bart.gov/news/articles/2022/news20220708-2 https://www.bart.gov/news/articles/2022/news20220708-2 High winds, lighter cars.
  - potatochup 4y ago
    It was originally designed that way to cope with high winds across the Golden Gate Bridge (even though those plans got scrapped)
    - clayhacks 4y ago
      Damn we should bring those back and put the wide gauage to use! BARTing into marin and beyond would be amazing
      - runarberg 4y ago
        You can take a ferry and then SMART all the way to San Bruno (I think they are planning an extension to Cloverdale, and eventually to Fort Ross). Personally I would rather want faster muni buses to the Avenues (or even the Persido) over BART to Marin, although People living there might disagree.
      - foolfoolz 4y ago
        marin has their own rapid transit now with a different gauge
    - deleted 4y ago
      [deleted]
  - arcticbull 4y ago
    I think this was the idea at the time but in reality it made little to no difference. There's an article I'll dig up to that effect.
  - nopenopenopeno 4y ago
    Chicago’s elevated trains have tipped over at least once. It’s not a pretty sight. A wider gauge might have prevented it.
    - midoridensha 4y ago
      Wider gauge also means larger maximum turning radius, so you can't take any tight turns that might be necessary in an already built-up city.
      - nopenopenopeno 4y ago
        Oh yeah, that wouldn’t work so well for Chicago then.
      - iggldiggl 4y ago
        Technically yes, in practice not really, unless you're proposing a ridiculously wide gauge (several meters, or something like that!). Even standard gauge trams have no difficulties navigating curves that are much tighter (25 m, down to 10-ish m on some legacy systems) than anything you'd seriously consider when building on a new rapid transit type rail system (normally at the very least a three-digit metre figure, ideally something more like 200 or 300 m). The only thing that directly scales with the track gauge is the length difference between the outer and inner rail in a curve and the minimum radius down to which the self-steering effect of conical wheels can still compensate this length difference. This means that with a larger track gauge you might get a little more wear and tear for the same curve radius, but a moderate widening of track gauge (e.g. BART is approx. 16 % wider than standard gauge) will equally not cause a dramatic effect here. In the best case, with standard gauge self-steering might work down to 150 m, which in the case of BART's track gauge would turn into 175 m, which is still rather on the tight side for a rapid transit-style line (and as originally built, BART didn't use conical wheels anyway, so they didn't benefit from self steering in curves regardless of radius used). The bigger factor in terms of curve radii is the length of your vehicles, how much vehicle throw you're prepared to accept in tight curves, and possibly whether you want to have trains with open gangways, so passengers are able to move between individual vehicles.
  - gpapilion 4y ago
    I always heard it was an attempt to keep anyone using the rail for carrying cargo or other comercial traffic. They had concerns folks would sabotage their growth in order to resell the lines later.
- einpoklum 4y ago
  55% of railway tracks in the world use the standard gauge; and most broad-gauges are less than 5'6". See: https://en.wikipedia.org/wiki/Standard-gauge_railway https://en.wikipedia.org/wiki/Standard-gauge_railway I doubt that BART has super-special stability issues necessitating 5'6".
  - jabl 4y ago
    BART was designed by aerospace engineers. They wanted to minimize weight. In order for the light-weight cars to not tip over in windy conditions they needed a broader gauge.
bluGill 4y ago
Also known as India broad gauge, which while not common isn't uncommon either.
- rob74 4y ago
  Besides India and neighboring countries, it's also used in Argentina and Chile, and the difference to the gauge used in Spain and Portugal is negligible in practice (only 8 mm): https://en.wikipedia.org/wiki/5_ft_6_in_gauge_railway https://en.wikipedia.org/wiki/5_ft_6_in_gauge_railway. Not sure if people in Argentina or Chile would say they are using "Indian gauge" though...
  - bluGill 4y ago
    > Not sure if people in Argentina or Chile would say they are using "Indian gauge" though... Unless they are a train geek they wouldn't say that, and probably wouldn't even know it. To people into trains it is known as Indian broad gauge, but most people won't know about such details, nor do they have reason to care. Though I would hope the operators know this - it makes it easier to order trains when you can use the industry terms.
MAGZine 4y ago
I don't think most parts and equipment are swappable anyhow. Maybe tracks themselves. But as far as the trains are concerned, you're pretty much buying all of the trains bespoke from the manufacturer. If SF used standard gauge rail, it's not like they could just buy some surplus rail cars, put some seats in them, and call it a day. Subways are generally lower to the ground because it improves stability and reduces roll. They corner better. I'm not sure that any subway system uses regular old heavy rail train cars. And besides, if you're ordering thousands of cars for replacement from bombardier (or whomever), you can order spare parts while you're at it.
- inferiorhuman 4y ago
  I don't think most parts and equipment are swappable anyhow. Maybe tracks themselves. But as far as the trains are concerned, you're pretty much buying all of the trains bespoke from the manufacturer. No you're not. Caltrain has plenty of secondhand rolling stock. Some of the newer coaches came from MetroLink, some of the older ones came from a railway in Virginia. Locomotives came from Southern Pacific and Amtrak. Muni runs all sorts of heritage equipment from around the world on the F, but the PCCs which make up the majority of the fleet were designed as a standard car. If SF used standard gauge rail, it's not like they could just buy some surplus rail cars, put some seats in them, and call it a day. Subways are generally lower to the ground because it improves stability and reduces roll. They corner better. I'm not sure that any subway system uses regular old heavy rail train cars. After the PCC of the 50s the feds tried for a next generation. In the end only Boston and SF bought the cars. They were utter crap in large part because (much like BART) it was mostly a pork project for defense contractors. In this case Boeing's new helicopter division (Boeing-Vertol) thought that trains were basically upside down helicopters and would be easy enough to build. Muni's current trams are based on an off-the-shelf Siemens design. The problem with BART isn't just the axles, it's the entire propulsion system, it's the wacky loading gauge, etc. BART can't even get away with a modified off-the-shelf system. And besides, if you're ordering thousands of cars for replacement from bombardier (or whomever), you can order spare parts while you're at it. Aside from the obvious problems with single sourcing things, that strategy only works as long as you can get spares. BART had huge problems finding thyristors a few years back because they use a non-standard voltage.
jabl 4y ago
From what I've read (I think there was discussion on HN about it a few months ago?), it's not only the gauge. The entire system was a 'clean sheet' design, made by aerospace engineers. Everything is totally different from what you'd expect in any normal (heavy, light, subway) train.
sidewndr46 4y ago
My understanding is BART also uses 1000 VDC for power rather than the more common 600 VDC.

I'm surprised the article didn't mention that BART is the only train in North America on the uncommon 5'6" gauge. This is another factor making parts and equipment more difficult to source.

djbusby 4y ago

It also makes the trains stable; wide stance.

carlivar 4y ago
Was it necessary to do that? A stability problem elsewhere?
- fuckstick 4y ago
  https://www.bart.gov/news/articles/2022/news20220708-2 https://www.bart.gov/news/articles/2022/news20220708-2 High winds, lighter cars.
- potatochup 4y ago
  It was originally designed that way to cope with high winds across the Golden Gate Bridge (even though those plans got scrapped)
  - clayhacks 4y ago
    Damn we should bring those back and put the wide gauage to use! BARTing into marin and beyond would be amazing
    - runarberg 4y ago
      You can take a ferry and then SMART all the way to San Bruno (I think they are planning an extension to Cloverdale, and eventually to Fort Ross). Personally I would rather want faster muni buses to the Avenues (or even the Persido) over BART to Marin, although People living there might disagree.
    - foolfoolz 4y ago
      marin has their own rapid transit now with a different gauge
  - deleted 4y ago
    [deleted]
- arcticbull 4y ago
  I think this was the idea at the time but in reality it made little to no difference. There's an article I'll dig up to that effect.
- nopenopenopeno 4y ago
  Chicago’s elevated trains have tipped over at least once. It’s not a pretty sight. A wider gauge might have prevented it.
  - midoridensha 4y ago
    Wider gauge also means larger maximum turning radius, so you can't take any tight turns that might be necessary in an already built-up city.
    - nopenopenopeno 4y ago
      Oh yeah, that wouldn’t work so well for Chicago then.
    - iggldiggl 4y ago
      Technically yes, in practice not really, unless you're proposing a ridiculously wide gauge (several meters, or something like that!). Even standard gauge trams have no difficulties navigating curves that are much tighter (25 m, down to 10-ish m on some legacy systems) than anything you'd seriously consider when building on a new rapid transit type rail system (normally at the very least a three-digit metre figure, ideally something more like 200 or 300 m). The only thing that directly scales with the track gauge is the length difference between the outer and inner rail in a curve and the minimum radius down to which the self-steering effect of conical wheels can still compensate this length difference. This means that with a larger track gauge you might get a little more wear and tear for the same curve radius, but a moderate widening of track gauge (e.g. BART is approx. 16 % wider than standard gauge) will equally not cause a dramatic effect here. In the best case, with standard gauge self-steering might work down to 150 m, which in the case of BART's track gauge would turn into 175 m, which is still rather on the tight side for a rapid transit-style line (and as originally built, BART didn't use conical wheels anyway, so they didn't benefit from self steering in curves regardless of radius used). The bigger factor in terms of curve radii is the length of your vehicles, how much vehicle throw you're prepared to accept in tight curves, and possibly whether you want to have trains with open gangways, so passengers are able to move between individual vehicles.
- gpapilion 4y ago
  I always heard it was an attempt to keep anyone using the rail for carrying cargo or other comercial traffic. They had concerns folks would sabotage their growth in order to resell the lines later.
einpoklum 4y ago
55% of railway tracks in the world use the standard gauge; and most broad-gauges are less than 5'6". See: https://en.wikipedia.org/wiki/Standard-gauge_railway https://en.wikipedia.org/wiki/Standard-gauge_railway I doubt that BART has super-special stability issues necessitating 5'6".
- jabl 4y ago
  BART was designed by aerospace engineers. They wanted to minimize weight. In order for the light-weight cars to not tip over in windy conditions they needed a broader gauge.

bluGill 4y ago

Also known as India broad gauge, which while not common isn't uncommon either.

rob74 4y ago
Besides India and neighboring countries, it's also used in Argentina and Chile, and the difference to the gauge used in Spain and Portugal is negligible in practice (only 8 mm): https://en.wikipedia.org/wiki/5_ft_6_in_gauge_railway https://en.wikipedia.org/wiki/5_ft_6_in_gauge_railway. Not sure if people in Argentina or Chile would say they are using "Indian gauge" though...
- bluGill 4y ago
  > Not sure if people in Argentina or Chile would say they are using "Indian gauge" though... Unless they are a train geek they wouldn't say that, and probably wouldn't even know it. To people into trains it is known as Indian broad gauge, but most people won't know about such details, nor do they have reason to care. Though I would hope the operators know this - it makes it easier to order trains when you can use the industry terms.

MAGZine 4y ago

I don't think most parts and equipment are swappable anyhow. Maybe tracks themselves. But as far as the trains are concerned, you're pretty much buying all of the trains bespoke from the manufacturer. If SF used standard gauge rail, it's not like they could just buy some surplus rail cars, put some seats in them, and call it a day. Subways are generally lower to the ground because it improves stability and reduces roll. They corner better. I'm not sure that any subway system uses regular old heavy rail train cars. And besides, if you're ordering thousands of cars for replacement from bombardier (or whomever), you can order spare parts while you're at it.

inferiorhuman 4y ago
I don't think most parts and equipment are swappable anyhow. Maybe tracks themselves. But as far as the trains are concerned, you're pretty much buying all of the trains bespoke from the manufacturer. No you're not. Caltrain has plenty of secondhand rolling stock. Some of the newer coaches came from MetroLink, some of the older ones came from a railway in Virginia. Locomotives came from Southern Pacific and Amtrak. Muni runs all sorts of heritage equipment from around the world on the F, but the PCCs which make up the majority of the fleet were designed as a standard car. If SF used standard gauge rail, it's not like they could just buy some surplus rail cars, put some seats in them, and call it a day. Subways are generally lower to the ground because it improves stability and reduces roll. They corner better. I'm not sure that any subway system uses regular old heavy rail train cars. After the PCC of the 50s the feds tried for a next generation. In the end only Boston and SF bought the cars. They were utter crap in large part because (much like BART) it was mostly a pork project for defense contractors. In this case Boeing's new helicopter division (Boeing-Vertol) thought that trains were basically upside down helicopters and would be easy enough to build. Muni's current trams are based on an off-the-shelf Siemens design. The problem with BART isn't just the axles, it's the entire propulsion system, it's the wacky loading gauge, etc. BART can't even get away with a modified off-the-shelf system. And besides, if you're ordering thousands of cars for replacement from bombardier (or whomever), you can order spare parts while you're at it. Aside from the obvious problems with single sourcing things, that strategy only works as long as you can get spares. BART had huge problems finding thyristors a few years back because they use a non-standard voltage.

jabl 4y ago

From what I've read (I think there was discussion on HN about it a few months ago?), it's not only the gauge. The entire system was a 'clean sheet' design, made by aerospace engineers. Everything is totally different from what you'd expect in any normal (heavy, light, subway) train.

sidewndr46 4y ago

My understanding is BART also uses 1000 VDC for power rather than the more common 600 VDC.