DutchRailnut wrote:a bell is usually only used on crossings with reasonable pedestrian traffic, this crossing would not need it.
In my experience, nearly every crossing I have seen that has lights has a bell. The one crossing I remember that does not have a bell is in a downtown area where there is pedestrian traffic (enough traffic that there are pedestrian gates - similar to the gates that close over the road but smaller - but no bell). It caught me off guard as (in my experience) I expected the crossing to have a bell and it did not.
There are crossing with only a crossbuck (no lights, bells or gates) so obviously there is no national requirement that every crossing have a bell (or lights). One should check the vehicle code for their state to see if there are any minimal standards for their state.
In my experience, the bell sounds while the gates are in motion and (at most locations I have observed) stops ringing when the gates are fully down. At some locations the bell rings continuously. At many locations I have observed the bell is no longer a bell but is an electric device that sounds like a bell mounted at the top of one of the crossing arm supports. At some crossings there is only one "bell" (generally single tracks where it can be heard on both sides).
Your experience may vary.