Rail requires periodic grinding to be maintained properly. When you see rail and wheels riding "flat" on each other, that's actually not how it's supposed to be -- that kind of maximum contact actually produces the squealing because the surface area has lots of opportunity to make friction-induced noise.
Supposedly, when you see a rail that's completely shiny on the top surface from being worn down, that's a sign that it hasn't been properly maintained.
A properly ground rail and wheel actually is only interacting on a very small edge of contact -- and this is what produces a quiet ride. A properly maintained rail will be quieter than almost any other mode of transport (noise from the contact surface). It takes active rail grinding though.
So actually, just a change to electric cars will not maintain quiet operations (although in the beginning I'm sure the newness of it will help). BART/Caltrain actually need to conduct the rail maintenance in order to keep it quiet.
Unfortunately, whether it's due to budget priorities being elsewhere, or an indiscriminate customer who puts up with this, unless that aspect changes, we'll be back in the same place. I don't even know whether the conductors -- the ones who would be among the first to notice such issues -- are even trained to understand this.
I encourage anyone to go ride the high speed rails of Germany, France, Italy, China, Japan, Korea, to understand what properly maintained rail is capable of feeling like. Or even the U-bahn in Munich, Frankfurt, too.
Noise on BART is due to a liberal application of NIH. BART literally reinvented the wheel – they used flat profile wheels (nobody else does this) which dramatically increased noise and wear. BART also spaced the tracks too tightly in turns further increasing noise and wear. They made their cars out of aluminum to save weight, creating a bit of an echo chamber (this got worse once they removed the carpeting). Caltrain doesn't have the luxury of lightweight rail cars since they share tracks with freight service.
BART doesn't bother greasing the tracks like nearly every other rail system (almost certainly an artifact of their homebrew train control system). Unfortunately while reinventing everything they opted against decoupling the wheels from each other (a.k.a. using a differential like a car or truck might).
Oh and let's not forget the Oakland Wye, BART's testament to noise, poor service, and political dysfunction.
Simply put BART can't really grind the rail fast enough to keep everything quiet for a meaningful period of time (if they could I assume the wear on the tracks would be astronomical). BART also needs custom rail grinders and whatnot because hey why not throw a custom track gauge into the mix.
So actually, just a change to electric cars will not maintain quiet operations
Caltrain is fairly quiet, at least inside. At the very least the electrification will certainly help with noise while stopped at a station.
I encourage anyone to go ride the high speed rails of Germany, France, Italy, China, Japan, Korea, to understand what properly maintained rail is capable of feeling like. Or even the U-bahn in Munich, Frankfurt, too.
Spain is missing from your list, they were instrumental in getting the Pendolino developed and, IIRC, have more high speed track than any other European country.
Is that worse than the SFO Wye? Samtrans had to create a bus shuttle from Millbrae to SFO because the BART service is so useless for traveling between Caltrain and SFO most times of day.
What's the story behind that??
Edit:
https://sanfrancisco.cbslocal.com/2019/05/07/brake-slamming-...
BART on the other hand has horribly loud screeching noises because of its idiosyncratic design choices.