"Trolleys" as in light rail operating on private r/w with grade crossings do have real horns, and they're loud enough (by regulation) to be annoying. At least as loud as a big truck horn, if not as loud as a freight locomotive, and usually quite obnoxious because they don't spend extra money on something that isn't going to be used often. If they share grade crossings with a regular railroad (as in parallel tracks) and it's not an official quiet zone, trolleys must sound horns just like regular trains. It's a safety issue.

Quiet zones don't eliminate crossing bells and horns. Horns may be, however, mounted on the crossing signals and be directed at the roadway/walkway. The decibel level can be lower and because of directivity they don't cause as much annoyance to nearby land uses. That way the train doesn't need to use the horn unless there's an emergency or safety issue (like somebody in the crossing who shouldn't be there). In some cases, where the gates may be down for some time (as with light rail where all the gates from one station to the next may close when a train is ready to leave), the bells might cycle off after a few minutes while the lights keep flashing; not sure if FRA allows that though. All things that need to be studied and considered when a local agency wants to do a quiet zone.

See "How To Create A Quiet Zone" at FRA: [www.fra.dot.gov]