Questions about railroad crossing bells?

1) Should they ring from the time the gates go down until they go back up, or should they only ring when the gates are going down and coming back up? 2) Is it better if they ring faster or slower? Which speed of ringing would you say is best? - https://www.youtube.com/watch?v=3H9B4Nk26q0&t=24s, https://www.youtube.com/watch?v=sDhnhUvM9ds, or https://www.youtube.com/watch?v=1h1NcIkggyM?
Answers

nycguy10002

They should only ring when the gates are in motion (either up or down). The bells should ring at a mid-range speed. They are not as effective at a slow speed or fast speed.