Five years ago, I surveyed a large shopping center. Previously, another firm had prepared an ALTA survey, but that plan had no elevations. We obtained the CAD drawing and needed to go and relocate most of the parking areas to record spot elevations and create contours.
Subsequently, a portion of the site was leased to a bank and they developed part of the parking lot into a branch office. To keep costs in line, we did not get elevations on that portion, but now must perform topo work again.
While looking over my old file, so that the party chief can return and have controls to utilize, I was struck by my traverse points that were hubs. I asked myself why in the world I had used hubs on the job. I carry wood hubs, stakes, and lath in my truck most days – so they are available – but I tend to use magnetic nails and generally put a plastic tab underneath. If they are set in grass, we will put flagging under the plastic tab so when you look for them 20 years later, the flagging will show first. When placing magnetic nails on pavement, I often use only flagging because the snowplows can grab the plastic tab and pull the nail out. So, why did I choose to set some of the traverse points as hubs? I must have had a reason. Could it be I simply had run out of magnetic nails?
Perhaps this could be the case of “Hubs v Magnetic Nails v Red Eyes v Concrete Nails.” I pay for any of the aforementioned markers out of my income, and I don’t skimp to save a few cents. What is most important to me is the investment I make in my field points to be used later on a future nearby project. The oldest points that I have set and used again were more than 25-year-old magnetic nails. Perhaps the oldest wood hub I have used was four years old.
On one construction stakeout, where I was able to obtain the CAD file for the project with the control points, they used hubs with tacks and found some of the pins on the boundary. I set up random points and located the boundary markers and some hard features like manhole rims and stormwater grates and door sills so I could rotate to match the plan and get on the same datum for elevations.
When I returned to the site to stake a building, I tried to stake out to the hubs. I found that I would go to the point where they had been, and when I was very close, I had a fill of three- or four-tenths. That indicated the stakes were left high up in the air rather than driven down close to the ground so a lawn mower would not knock them out. I wondered at the logic of setting a wood stake that was sure to be hit by lawn mowers and, therefore, be of no use when someone who worked for that same firm and prepared the original topo returned?
Hub and Tack
What are the positive aspects of using a hub and tack? If you know the traverse point will not last long and the ground is mushy, then it seems like an acceptable use. When I am staking out a house, garage, manholes, etc., I like to use hubs since they are easier to see for machine operators and they hold their position well. After staking offset hubs, I locate them, so they become a possible control point for later in the project. I like hubs for temporary markers.
Once, when I was performing a large tract survey, someone had surveyed the neighboring farm and instead of setting pins or stones, they set a hub and put a lath next to it marked “PROPERTY CORNER.” I believe if surveyors are not sure of themselves and do not want any long-term responsibility for the corners they set, then a wood stake is the way to go … but I would not do that.
“Red Eyes” are a Missouri or Delaware term for a carpenter’s nail pushed through a folded piece of flagging. On rainy days, the crew members would make up red eyes and fill a coffee can with them to keep in the truck. While chaining, the party chief would make a kick, flatten out the dirt, and then make a small punch mark with his plumb bob and stick a red eye into the hole. These nails give off a magnetic signal, but not as strong as a magnetic nail.
A local land surveyor was helping me out by sharing his computer file so I could recreate boundary points that had been lost on my parcel. He didn’t think I would find his nails, but mentioned that there were mag nails too. I found all of his red eye nails with their flagging along with his magnetic nails and they all worked well. When looking for those red eyes, a person must realize the signal may be faint. It was fortuitous that he mentioned they were merely nails with flagging when we spoke on the phone, so I would not dismiss weak magnetic locator signals.
Where I pay for the magnetic nails from my profits, I prefer my party chief to spend money on substantial markers. This is to increase the possibility of finding traverse points when we return, even if it is 25 years later.
Concrete nails and “Hilti Nails” are great if they are labeled as such on plans. If a Hilti Nail is set as a traverse point and has a washer underneath, it may be easy to find again. I don’t like concrete nails as traverse points and use them only if I run out of good things to set. They are too small, too short, and, in pavement once the flagging comes off, they are very difficult to see.
In this area, a surveyor gave me his computer file for his site and called for a nail. When I finally found it, I saw it was a concrete nail. I don’t believe he was cheap; rather, I think he may have been color blind and the nail showed up well for him.
A fluted concrete nail can work well if you are construction staking and must set markers in the road that are temporary. They can be set as red eye with a spray paint circle. I have staked proposed islands and curbs in existing parking lots where they would saw-cut the pavement, install curbs, and then put a fresh topping of pavement for the entire lot. This also works using Hilti Nails with flagging underneath. For setting permanent corners in pavement, mag nails, spikes or specialty markers are my choice.
The expression “the right tool for the job” is applicable for traverse point markers. If you looked at one of my CAD files and a traverse point was labeled “MARK,” don’t waste time looking for it four weeks later. When a point in the woods is coded “DIME” or “NICKEL,” what would the odds be that you are going to find it without moving it? Obviously, I’ve run out of nails and set whatever I had in my pocket rather than walk back to the truck. Those occasions are not when I am locating pins and monuments, but rather trees and elevation shots and will immediately occupy the point.
I recall setting up a traverse and driving a nail on the trunk of a fallen 5-foot-thick oak tree. With the root mass perpendicular to the ground, the point was perhaps 8-feet off the ground and a bit of work to get up to it. The tree was as stable as the ground surrounding it. The instrument person loved the challenge and appreciated me incorporating it into the survey. We can all enjoy the chance to be creative.
As part of a small area of topographic surveying at a local university, I set a magnetic nail on the top of a high gravel pile. It had been there for a while and was somewhat settled. While it worked very well for that day, that was not a long-term solution. I have noted stakeout crews setting a long-term use control point on the crest of a topsoil pile. Sure, you could see the whole project from there, but that pile was not compacted or solid thus would/could move in any direction except up.
It’s obvious I am a fan of magnetic nails, but I am not keen on setting mag nails for traverse points in the road where they will be paved over. I like mag nails and magnetic nails in the joints of curbs if they are tight. Putting a control point between the curb and the sidewalk seems like it protects my instrument from cars and pedestrians. Early on, I tell employees not to set a nail right at the back of a curb or the edge of a sidewalk because some people like to use power trimmers to clean that area up and they destroy nails. If I show them a sidewalk with a deep cut along the edge, they understand immediately.
Becoming More Obvious
Years ago, I got a friend a job where I was working. After a few weeks of land surveying and construction staking, he remarked at how many survey points he was now seeing. They had been there the whole time, but he was just now noticing them. White crosses painted in the road, PK nails in sidewalks, lath running across a field where a curved road would soon be constructed, etc.
I instruct field people to keep their eyes open for survey markers as they walk along the roads, curbs and sidewalks. They are to locate them as much as is practical for two basic reasons. First, their own points may be torn out and these are backup markers. Second, if we get someone else’s CAD file, they may be one of their control points from the traverse and it will help us lock in our points to theirs.
Just today, I instructed my apprentice to put some flagging on the wire fence directly over a pin we found and would locate. It was not our lot corner, but I had him put it on for the next surveyor to come along in order to make their life a little easier and help them agree with whatever decision I came up with on our boundary survey. When surveyors were first allotted pink as the survey color, I was let down. Today, I’m glad we got that bright color all to ourselves, especially when I see that small knot of flagging on a twig or fence and inside I say, “Thank you!”