3 ms·

> the track pitch I think the term you're looking for is track gauge. And as for a need to widen it in curves, the answer is basically it depends. On mainlin

> the track pitch I think the term you're looking for is track gauge. And as for a need to widen it in curves, the answer is basically it depends. On mainline railways gauge widening in curves basically stems from the days of steam locomotives, which mostly didn't have bogies (at least for the main driving wheels) and comparatively enormous wheelbases. On straight(ish) track, some minor gauge widening as compared to the nominal standard gauge might nowadays also be beneficial, especially on high speed lines. Within the context of streetcars/trams, which often need to negotiate very tight curves on the other hand, current state of the art seems to indicate that a slight gauge tightening might actually be more beneficial in order to avoid too large a skew angle between the bogies and the rails. (Compare http://interfacejournal.com/archives/472 http://interfacejournal.com/archives/472) I'm no wheel/rail-interface guru, so quite what the conclusions from that would be for BART I can't say, either, but just wanted to point out that the topic is somewhat more complex, and nowadays gauge widening in curves might not actually always be the right answer.

inferiorhuman 4y ago
> I think the term you're looking for is track gauge. No. Track gauge is the nominal width, no? I'm talking about how the width changes in the curves. A while back a former BART engineer went on the record claiming the spacing in the curves was contributing to the noise. Top to bottom BART fully embraced NIH. Fifty years ago there was good reason but now the rest of the rail industry has moved on and BART is stuck with a lot of tech and engineering debt. For e.g. BART can't grease or sand their tracks either, and you can feel the older trains slip and slide (and damage the track) as they exit the station. Edit: Here's an interesting piece on noise. Note how nearly every other rail system lubricates the tracks (BART can't) and how no other rail system uses (noisy) solid aluminum wheels. https://www.bart.gov/sites/default/files/docs/noisereport.pdf https://www.bart.gov/sites/default/files/docs/noisereport.pd...
- iggldiggl 4y ago
  > No. Track gauge is the nominal width, no? I'm talking about how the width changes in the curves. I'm not intimately familiar with the English terms, but I think it still all boils down to the track gauge. That Boston article I linked to certainly talks about track gauge and gauge-widening and the like.

inferiorhuman 4y ago

> I think the term you're looking for is track gauge. No. Track gauge is the nominal width, no? I'm talking about how the width changes in the curves. A while back a former BART engineer went on the record claiming the spacing in the curves was contributing to the noise. Top to bottom BART fully embraced NIH. Fifty years ago there was good reason but now the rest of the rail industry has moved on and BART is stuck with a lot of tech and engineering debt. For e.g. BART can't grease or sand their tracks either, and you can feel the older trains slip and slide (and damage the track) as they exit the station. Edit: Here's an interesting piece on noise. Note how nearly every other rail system lubricates the tracks (BART can't) and how no other rail system uses (noisy) solid aluminum wheels. https://www.bart.gov/sites/default/files/docs/noisereport.pdf https://www.bart.gov/sites/default/files/docs/noisereport.pd...

iggldiggl 4y ago
> No. Track gauge is the nominal width, no? I'm talking about how the width changes in the curves. I'm not intimately familiar with the English terms, but I think it still all boils down to the track gauge. That Boston article I linked to certainly talks about track gauge and gauge-widening and the like.