Back to Basics: Turning 50
As I contemplated what to write about in my 50th article for POB, I went back and reviewed my previous articles to see what topics I had covered. I also wondered if there is still a need for a column titled “Back to Basics” considering the changes in technology that have occurred in the 13 years that I have been writing.
The articles I have written over the years have covered a diverse range of topics related to surveying and layout and also some topics that were somewhat philosophical. I have consciously made an effort with every article to select topics that I thought would be of interest to all readers but especially individuals who were just entering the field of surveying. I felt that those who were new to the profession may not be aware of some of the basics of surveying measurement, the fundamentals of instrument use or the standard layout techniques. Fortunately for me, there are always individuals in our profession who can benefit from a review of the basics.
My articles from the past can be separated into a number of distinct categories--including planning, communications, instrument setup and use, calibration, equipment care, mistakes and errors, layout techniques, quick checks, rules of thumb, standard practices--as well as some miscellaneous topics.
One of my favorites was titled “Mistakes and errors from the field” (November 2004) and was based on a questionnaire I sent out to construction layout surveyors as I was working on the 3rd edition of my book, “Construction Surveying and Layout.” Just a few of the common mistakes respondents had listed included writing the wrong elevation on a stake and using that elevation to locate a footing; laying out the mirror image of the structure because of lack of understanding of what the plans are communicating; transposing numbers when measuring distance by chaining; using a foot chain and converting to a metric measurement; not holding the prism rod plumb causing the distance to be wrong; not setting up an electronic instrument exactly over the point and not checking to see if the instrument was still level after using it for an extended period of time; not understanding the potential sources of error in total station measurement; failing to turn equal numbers of direct and reverse angles when turning angles; not leveling the instrument when the vertical angle was measured; not “closing the loop when leveling”; not calibrating the instrument before leveling; and being so concerned about the decimal part of the reading when leveling that we read the wrong foot mark.
In “Long backsight and short foresights” (November 2003), I outlined how having a long backsight and a short foresight is a fundamental principle that should always be followed. It is a principle that affects the size of errors in the sighting and angle measurement process of layout. By having a long backsight and a short foresight, the size of sighting errors can be reduced--which is a goal of any good construction layout surveyor. It sometimes isn’t convenient and may take more effort to provide a long backsight by requiring someone to walk long distances, but the rewards are great by ensuring that errors will be reduced.
Another favorite of mine was my March 2008 article on “The one-minute, one-person peg test.” In this piece, I explained how a peg-test area could be set up using a yardstick, a piece of level rod or a section of carpenter’s tape positioned at exactly the same elevation on two stationary objects 200 to 300 feet apart with a clear line of sight between them. Using this peg-test area, one person can perform a calibration test in less than one minute.
Other topics that I have written about over the years include pacing, rules of thumb, quick setup with an optical plummet, leveling an instrument, instrument use, chaining, total stations, lasers in construction, planning, preparation, seminars and education, the role of field engineers, dressing for safety, tolerances, and calculating directions with azimuths.
Oldies but Goodies
Whew, I’m glad I did not have to write all of these articles at one time. It makes me tired to think about all of the effort involved.
I realize some procedures that I have written about are no longer used on a daily basis by many surveyors. I even had someone once say to me, “You’re the guy who writes about the old methods.” Yep, that’s me. Regardless, I do strongly believe that some surveyors and surveyors-in-training still need to hear about some of these old methods of layout and measurement because many of them are still relevant. When the power goes out on the total station or GPS system, knowing some of the “old techniques” may save the day.
I think I can conclude that “Back to Basics” will be applicable for a few more years as long as layout points are put in by people.