So they say indeed! Interesting! I have lived there long enough and didn't notice. They are all pretty quiet. To be fair, it's possible to run on rubber and still mess it up, noise-wise, like BART does with gusto.
To follow up on my previous comment: BART is a master class in institutional incompetence, the Peter Principle in action if you will. So, yes, BART uses steel track and wheels with a steel outer surface but they've still managed to fuck it up ten ways from Sunday.
The article you linked to talks about all the money that BART's thrown at the noise problem without addressing the elephant(s) in the room: BART cars are aluminum tubes that are inherently noisy and BART wears its tracks aggressively. The first iterations had carpeted floors which absorbed some of the noise, but those got predictably gross.
Much of the track noise comes from corrugation because the wheels are dragged over the track. Other systems might grease their wheels so that there's more slip in turns, BART can't. Other systems sand the tracks in wet weather so you don't skid, BART can't. Modern systems have anti-skid systems so that you don't wear the wheels. Bombardier's anti-skid system is awful. So the new cars flat spot the wheels at a much higher rate than the old and you get noisy track (and noisy trains as they thump thump thump down the track). BART grind the rails and the noise goes away for a bit, but it eventually comes back with a vengeance because they're doing everything they can to avoid addressing the underlying problems.
