4 ms·

you got me curious. "wind stability" is the given reason: https://www.bart.gov/news/articles/2022/news20220708-2 https://www.bart.gov/news/articles/2022/news2

by froh 3y ago

you got me curious. "wind stability" is the given reason: https://www.bart.gov/news/articles/2022/news20220708-2 https://www.bart.gov/news/articles/2022/news20220708-2 and it is a standard gauge, "Indian gauge", just not the standard gauge. which keeps it free from freight trains and other mixed traffic, which helps with punctuality. also if they wanted to change that they could introduce a dual gauge track, like the Stuttgart area did for their mixed tram/underground https://en.wikipedia.org/wiki/Stuttgart_Stadtbahn#/media/File%3AStuttgart_dt8.jpg https://en.wikipedia.org/wiki/Stuttgart_Stadtbahn#/media/Fil...

bobthepanda 3y ago
Wind stability was a given reason back when it was planned to cross the Golden Gate Bridge, but that never happened BART’s planning is basically a comedy of errors by aerospace engineers who specifically did not want to learn anything from other rail systems, hence the nonstandard car layout, the nonstandard electrification, the nonstandard wheels that make too much noise, etc. BART themselves clearly do not believe much of it anymore given that they operate a standard gauge line.
- Spooky23 3y ago
  I recently visited SFO for the first time and loved the transit system - although the noise level of BART seemed… excessive. Really stood out in the trip from the airport it was significantly louder than my flight. I was worried I was losing my mind, thanks for confirming that it’s real.
  - mh- 3y ago
    I used to ride BART 4-5 days a week, through the Transbay tunnel. I frequently got the "sustained loud noise" warning from my watch, notifying me that the combined duration and intensity of the ambient sound was enough to damage one's hearing.
adrianmonk 3y ago
I'm curious if they could have solved the crosswind stability issue with fences along the track to block the wind. Although fences cost money, and it would ruin the view.
- froh 3y ago
  we do have Wind in Europe. and regional transport. and rapid transport, too. no cross wind fences. simply not needed.
  - adrianmonk 3y ago
    Did you read the report[1] in the page that you linked? On p. 2, it explains that the BART cars were specifically designed to be lighter weight than normal rail cars in order to minimize the energy required to rapidly accelerate to 80 miles/hour (129 km/hour). The lighter weight makes them less stable in crosswinds. On p. 13, there's a short cost analysis, and their conclusion is it will save them $2 million overall because it will cost additional money to build but will save even more money on energy. So it's a different trade-off. They gave up stability to gain energy efficiency. So they then did something to regain the lost stability. --- [1] https://www.bart.gov/sites/default/files/docs/BART%20Stability%20Study%20Compressed_0.pdf https://www.bart.gov/sites/default/files/docs/BART%20Stabili...
    - froh 3y ago
      sure I read it. however if that concept of ultra lightweight cars was sustainable, more nations would do it, wouldn't you think? what's done instead is recuperation of break energy as electricity. the concepts looked good on paper but they didn't work out as well in practice.
  - callalex 3y ago
    Civil engineering is incredibly complex and full of nuanced trade offs. If you find it to be simple, it is your lack of understanding of the topic.

by froh 3y ago

bobthepanda 3y ago

Wind stability was a given reason back when it was planned to cross the Golden Gate Bridge, but that never happened BART’s planning is basically a comedy of errors by aerospace engineers who specifically did not want to learn anything from other rail systems, hence the nonstandard car layout, the nonstandard electrification, the nonstandard wheels that make too much noise, etc. BART themselves clearly do not believe much of it anymore given that they operate a standard gauge line.

Spooky23 3y ago
I recently visited SFO for the first time and loved the transit system - although the noise level of BART seemed… excessive. Really stood out in the trip from the airport it was significantly louder than my flight. I was worried I was losing my mind, thanks for confirming that it’s real.
- mh- 3y ago
  I used to ride BART 4-5 days a week, through the Transbay tunnel. I frequently got the "sustained loud noise" warning from my watch, notifying me that the combined duration and intensity of the ambient sound was enough to damage one's hearing.

adrianmonk 3y ago

I'm curious if they could have solved the crosswind stability issue with fences along the track to block the wind. Although fences cost money, and it would ruin the view.

froh 3y ago
we do have Wind in Europe. and regional transport. and rapid transport, too. no cross wind fences. simply not needed.
- adrianmonk 3y ago
  Did you read the report[1] in the page that you linked? On p. 2, it explains that the BART cars were specifically designed to be lighter weight than normal rail cars in order to minimize the energy required to rapidly accelerate to 80 miles/hour (129 km/hour). The lighter weight makes them less stable in crosswinds. On p. 13, there's a short cost analysis, and their conclusion is it will save them $2 million overall because it will cost additional money to build but will save even more money on energy. So it's a different trade-off. They gave up stability to gain energy efficiency. So they then did something to regain the lost stability. --- [1] https://www.bart.gov/sites/default/files/docs/BART%20Stability%20Study%20Compressed_0.pdf https://www.bart.gov/sites/default/files/docs/BART%20Stabili...
  - froh 3y ago
    sure I read it. however if that concept of ultra lightweight cars was sustainable, more nations would do it, wouldn't you think? what's done instead is recuperation of break energy as electricity. the concepts looked good on paper but they didn't work out as well in practice.
- callalex 3y ago
  Civil engineering is incredibly complex and full of nuanced trade offs. If you find it to be simple, it is your lack of understanding of the topic.