BLOCK INDICATOR by Metro Digital Resources Librarian • April 14, 2016 A device, generally located near a turnout switch, that is used to indicate the presence of a train in the block or blocks leading to that switch. (TRB) Share:Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Reddit (Opens in new window)Click to email this to a friend (Opens in new window)Click to print (Opens in new window)Like this:Like Loading... Related