I live outside Muni/Caltrain. They're not great, noise-wise, but the motorcycles are 10000x worse. I get a number going by a day, and I just can't understand why they're allowed to be so absurdly loud.
Buses/trains are relatively quiet, outside of a few edge cases like tracks scraping or honking when someone's in their way - rare occurrences.
My dorm was a bus stop. Each time the bus came there were air brakes, a recording announcing the route and station, and the warning beeps for kneeling and wheelchair ramp extension. Fortunately it did not have a shelter, as many bus shelters in Chicago now beep continuously so that blind people can find them.
My first apartment was outside a level crossing frequented by Amtrak and Union Pacific. The federally required horn blasts - 2 long, 1 short, 1 long - overwhelm anything you might be doing or thinking about, resonate in your chest cavity. The building shakes, and the air becomes thick with diesel fumes and sediment kicked up from the railroad bed.
After an hour, I forget that the freeway is even there.
I'm on an intersection with caltrain, muni, and a freeway, but of course it can only be so informative. I'm not trying to say "Buses and trains aren't a problem" at all, I'm saying fuck motorcycles.
The Caltrain (and other trains but Caltrain is more frequent) going by San Mateo is brutal. Their horn is almost constantly on due to the many ground level intersections and they are ear drum busting loud (by regulation no less).
Areas where every level crossing is this good can be designated as quiet zones, but few municipalities want to spend the money on that. Train tracks are usually in industrial/commercial areas; homes near them are, shall we say, not centers of political power.
My intuition about this is that the deflection, intensity, and directionality of the noise from motorcycles impacts street level noise more than trains in a rail corridor. I believe that is why good street planning incorporates natural features that absorb and deflect noise, like greenery on street corners, for example.
Buses/trains are relatively quiet, outside of a few edge cases like tracks scraping or honking when someone's in their way - rare occurrences.