These poles were once common along the MoPac's Sedalia Subdivision through Missouri, and systemwide, for that matter. They largely disappeared back in the early 1980s as far as I can tell. This one likely survived because it shared space with the signal code line, which used the three arms seen on the right pole of the structure. The code line was removed in 1998, and I guess it is easier to just leave this one here, given the proximity of buildings, street, and other tight space restrictions. Washington, MO 2/26/2010.