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 rai

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...