Looking at the chart on the bottom left on pg 12 https://www.bart.gov/sites/default/files/docs/BART%20Stabili... 6 ft+ gauge rail looks to be required just to get the 0 margin of stability to withstand the 100 mph+ wind speeds San Francisco has seen https://www.nbcbayarea.com/news/local/23-years-ago-strong-st... Although, it would make more sense to stop running the trains in 67 mph+ winds due to the average individual being pushed adversely by the wind such as at a station.