Those are part of those sh*t-eating quiet zones. The object at the top indicates if the engineer has to give the ol' "long-long-short-long" for the crossing or not, while the lower object is a speaker that plays a simulated train horn (usually a recording of a K5LA like those used on some light rail trains like in LA, Portland, and Salt Lake City; the crossing at the quiet zone in San Clemente plays a sound of ATSF 3751s whistle).