Voting has started for the Level crossing train horn usage (quiet zones, whistle bans) feature proposal: Proposal:Level crossing train horn usage - OpenStreetMap Wiki. Note that this proposal now uses crossing:whistle instead of the originally proposed crossing:horn (this change was made relatively late in the RFC process).
Please, cross post this announcement on the tagging mailing list on my behalf by sending an email to: tagging@openstreetmap.org