As someone who lives near a railroad crossing, I'm not exactly a fan of the horns at 2am.
Why not have a signal light on the tracks before the crossing which indicates that the crossing is working correctly, along with signage: "IF LIGHT IS NOT FLASHING, SOUND HORN AND SLOW TO ___MPH."(*) I understand that if the crossing gates and lights aren't working the horn provides some safety factor, but if the lights and gates are working, I fail to see how the horn does anything other than add annoyance.
(*) That would be the simplest means of letting people sleep without adversely affecting safety. An alternative, if the trains on a route would be equipped with standardized "navigation" equipment, would be to have the gates communicate their status to the locomotive via wireless or other means. That could provide an engineer greater notice of a gate that could be expected to fail (e.g. because it doesn't have power).
We moved here in 1994, the no-horn gates weren't installed until last year. Our house is 3 houses down the first street from the crossing. The blowpost for southbound trains stands 185 yards from our bedroom window (or so says my trusty Bushnell rangefinder).
I didn't mind the horns. It was kinda nostalgic. We had 37 trains a day, plus specials. The first couple of weeks we lived here it was annoying, after that we didn't even notice. Slept right through, even with the bedroom windows open.
With that said, I used to investigate crossing accidents for the old Southern Railroad. Your suggestion simply adds more electronics and more things to go wrong, plus a sign that nobody will read. Our almost-accident a few years ago was an idiot who drove around a large "CROSSING CLOSED" sign. We were walking our dogs when he drove his jeep onto the crossing - they had removed the asphalt to repave, and he drove right into the hole and his front bumper stuck under the first rail. About that time we heard the horn two crossings north . . . .
My husband dove into the Jeep and forcibly hauled the man out, while I hared home with the dogs and brought back our Expedition and a logging chain. Hubby was just hooking up the chain to the Jeep's rear bumper when the headlight came around the curve. Fortunately the engineer was under a go-slow order and brought his train to a halt about 50 feet from the Jeep. The engineer was cussin' mad, needless to say.
You can't fix stupidity.
The European gate does prevent anyone from jumping the crossing if the gates are working properly. But old Murphy hangs around railroad crossings a lot.