The more rural an area to survey, the more important it is to have corners well marked. Witness posts are placed to mark a corner monument that otherwise might be missed. Piles of stones around a pin help, especially when the deed or the plan a deed was written from calls for the “pipe in stone pile.”
While working on field crews subcontracted to the Army Corps of Engineers for high-accuracy control traverses in Kansas, we learned the Corps way of documenting a traverse point. We set the pin for the traverse point, then placed two or more reference pins from which you could reset the traverse pin. Angles were turned and distances measured to the reference points. Trees, bridge wing walls, edges of pavement, and buildings were then used for taping ties to all of the above. This went into the field notes so that anyone who might follow our footsteps could find our point. The Army Corps took great pride in their methods and expected precision and speed from us in setting the traverse point and related witness markers. Since the shortest allowable length of a traverse line was 1,600 feet, it would not be easy to find an old traverse point without good drawings and reference points. The longest line I remember was three miles, but I’m sure in other states surveyors traversed much longer distances.
Employees at a rural surveying firm, to whom I was subcontracted, employed their own policy of marking corners in the deep woods. At pins and monuments, they would blaze up to three trees with the blaze facing the corner. Sometimes they measured from the blaze to the corner. If you were out in the woods trying to find one of the corners called for on their plans and happened to see a blazed tree, you would then step back from it and look around for other blazed trees and then geographically center yourself to face all the blazes from one position. It worked well. Their plans did not mention the blazes, but did label the monuments. You might say they were blazing a future of higher profits for their company when they followed up their surveys at a later date.
I am a big fan of locating telephone poles with the reflectorless option of my robots. They are easy to measure and record, and provide a means of finding traverse points, especially when they are down the road a distance from the project where few hard items might have been located. They become my reference pins like the ones we set for the Corps and allow me to get within a few feet of my magnetic nails. Manholes, street signs, building corners, and water and gas valves can often be located reflectorless, so you don’t have to venture into the highway or spend any time walking to and from them. As long as you have a node in the CAD file, you can print it out and scale the distance to your control point, and then pace or measure to get close. The minutes it takes to locate these remote items can save an hour in running controls back in if you cannot find your points. Also, there are times when I set magnetic nails or pins and return with a pin finder to realize there are many magnetic signals keeping me from deciding where to start digging.
A nail set behind a guard rail provides for a safe setup next to a significant magnetic disturbance. If I had located a pole nearby, I could measure from the pole to that traverse point and then from the guard rail to find my magnetic nail. Similarly, if you set a traverse point near the rails for a train, you will often find many plates, spikes and such, and need to have a pole to measure from, plus utilizing a measure from the nearest rail.
Another good reason to locate poles and such is when the office prepares deed plots, they will send the surveyor back out to look for boundary points with tie distances from your locations. If the poles and edge of pavement have been located, one does not necessarily need to get out the instrument to search. You will be pacing or taping from the poles, and edge of pavement will get you within a few feet of the possible location. This is a real time saver when the return trip does not produce monuments to locate.
Recently, a crew chief ran a traverse leg to locate some nice lot corners in a subdivision a few lots away from the subject property. His back sight was 300 feet and over a 50 foot deep valley and set on an opposing hillside surrounded by 30 feet of grass in every direction. The back sight would be difficult to find when the wire flag disappeared when spring arrived. There would not have been good reference points from which to measure to find that point.
The traverse point, however, was a mag nail in old blacktop in front of a maintenance garage for the neighboring golf course. Once the flagging wore off the mag nail, it too would be difficult to find. When I visited the site and set up on the mag nail and back sighted across the valley, it was evident that if I returned in the spring, the line of sight would be impossible. Looking at the mag nail, I thought how I would ask him next time to locate without a reflector the maintenance garage, the concrete pad nearby and the shed next to it, and then draft them for possible future work. Then we would have the reference points needed for finding the mag nail. The line work would be outside the area shown on the final survey drawing, but still exist in the cad drawing for many years.
I prefer using magnetic and mag nails for traverse points. More than 25 years ago, I surveyed a property with a long frontage on a PennDOT highway having a right-of-way line that jogged in and out. It was a lot of work to establish that right-of-way line, so when I was given a project across the street, I went back in the field and found my old magnetic nails and quickly had the right-of-way solved. The old magnetic nails were a small investment that paid off big in terms of time.
Lastly, I would like to point out that when field personnel set extra control points and reference points, and locate items like poles for later reference use, they can also make their own lives easier. They will be the ones sent back out to set the final corners. They will be the first choice to stake construction improvements. Theirs will be the logical choice to perform the as-built survey. If they get the job done faster using known coordinate points so the office staff does not have a lot of computations to rotate and translate field coordinate points to match the old plan, the office staff will remember these pros such as you are easier to work with. They will request you on their projects, and the boss will see that you are highly qualified.
Invest in your future. Leave marks for others, your employer and yourself. Twenty-five years from now, you might thank yourself for the work you do today.
Jeffrey P. Turner, PLS, began his career in surveying in 1971 and became licensed in Pennsylvania in 1987. He was co-owner of a surveying firm for six years before launching his own firm in the Philadelphia region in 1995. He is passionate about leaving footsteps for future generations of surveying professionals. He can be reached at firstname.lastname@example.org.