Here is the long-awaited update
to In Search of ARL5,
with few additional details, but with more pictures. Hopefully these pictures are a little
clearer. Please note, before you "click to enlarge", that the large
pictures are about 300 k-bytes each.
The wooden stake has been moved a little since my last visit. (Looking generally west.)
Here is the cover with the shadow of the wooden stake.
The cover is open, and there is more dirt than I saw last time, but you can see there is
just a little indentation in the end of a steel rod. That's the ARL5-A reference point,
which is located at exactly
32° 45' 30.04048" North,97° 03' 43.02741" West, at
an altitude of 533.51 feet.
Out behind the building there is a short self-supporting tower.
This tower holds a GPS reference antenna.
Somewhere on the bottom of this antenna is the reference point known as ARL5, which
is at exactly
32° 45' 32.49931" North,97° 03' 36.99084" West, at
an altitude of 562.1 feet.
In the center of the base of the tower is brass disk, which is a Texas Highway Department (TXDOT)
benchmark. I completely missed this one during my first two visits to the site; after all, who
would think there would be one reference mark directly under another one? The
official datasheet for this mark is
The disk is engraved with "Texas State Department of Highways & Public Transportation", which
was the name of the Highway Department before it
This brass marker is somewhat larger than most benchmark disks.
There is another benchmark out by the dumpster.
This is a TXDOT marker, considerably smaller than the one under the GPS antenna tower.
Here is a close up shot of the marker.
Finally, on July 20, 2003, I made it out
to ARL5-B, the
last of the benchmarks on this site, and the most difficult to reach. It's out in the
weeds about 250 yards east of the TXDOT parking lot.
Using the description in the official data sheet, and a GPS receiver, I could have found this
mark, I guess, but the witness post surely helps.
And the witness post is a good place to hang the GPS while taking pictures.
Here is the station, just as I found it, with the cover closed.
With the cover open, you can see the mark is in excellent condition. That is
probably because it is so difficult to reach this spot.
This shows the size of the hardware involved, if you've never seen one of these.
I would have taken more pictures, but the temperature was at least 100°, and there were
lots of insects and other animals living in these big cracks in the ground, so I didn't want
to stay out there all day.
Document location http://www.ae5d.com/arl5a.html
Updated August 10, 2003.