The Greens Creek mine, owned and operated by Hecla Mining Co, produces gold, silver, lead and zinc from an underground mining operation on Admiralty Island, Alaska. Employees must travel a 19-kilometer, single-lane access road to access the mine site, which is shared with ore haulage and freight trucks. Hecla sought a simple and robust way to augment its radio call-out procedures to increase driver awareness of approaching traffic and improve safety on the access road.