There's the same Whistle post as seen from the opposite direction.
This non-descript location is significant because it is the
western terminus of the Mt. Airy Cutoff. Click on the picture
to enlarge it, then look carefully at the bottom right, and you may
spot the rusty rail hiding in the weeds. That rail is an artifact
left over from the OML's original alignment.
Prior to the construction of Mt. Airy Tunnel and Cutoff, from
here east to Bush Creek, the original alignment had run roughly
parallel just to the south. Upon opening of the Cutoff route in
1902, the original alignment was abandoned, except for a portion
that survived for decades as a siding into Monrovia.
A virtual tour of this disused original alignment appears on other
pages at this site.