I’ve seen these next to many rail-trails, and I’ve been wondering what they are. Could someone shed some light on these?
(If this helps, the photo was taken in the Blackstone Valley, Rhode Island.
Thanks,
Purely a guess but the hole could be for setting up a transit if the rails ever need to be relaid. The plumb bob hanging fron the transit would be cenetered on the hole for allignment purposes
…That would be my thought…A surveying bench mark.
You guys are close, but not exactly. Allow me to contribute some of my 15+ years experience as a land survey party chief to help answer the question.
What you’re looking at is a Rhode Island “Horizontal Boundary” (property corner) monument. Unlike a benchmark whose values are based on a vertical datum, either National Geodetic Vertical Datum of 1928 (NGVD 1928) -or- North American Vertical Datum of 1988 (NAVD 1988) which translates into decimal feet elevation above or below sea level, a boundary corner’s values are based on the individual state’s horizontal “State Plane Coordinate System” which translates into northing (x) and easting (y) values for that particular point. That’s not to say that there’s not a recorded elevation on that monument, just that it’s primarily a horizontal reference point.
Thanks! Are these installed all over the place or just next to rail lines/rail trails?
You’ll find some kind of monumentation at any recorded property, boundary, right-of-way, etc. corner or somewhere in the vicinity of where a corner falls if a monument cannot be physically set. Other examples of monuments or markers include iron rods, pipes and nail/discs if in asphalt or concrete as in the case of centerline monumentation within roadway right-of-way limits.
The monument in the photo is one example of a wide variety found/set by surveyors all across the country. As a surveyor, I’d expect to find one of these anywhere the boundary lines change direction, PI, PC or PT (Point of Intersection, Point of Curvature or Point of Tangency). Or, in the case of lengthy lines or cuves (usually greater than a quarter mile), at POL’s or POC’s (Point On Line or Point On Curve). A good map which delineates boundaries is a very useful tool in finding property corners.
I saw somthing like that on MacGyver once, I He stuck a septer in the hole and it opened a hidden wall when the sunlight hit it the right way [;)]
Ted. What do the letters mean?
(R)hode (I)sland (H)orizontal (B)oundary