LTE: Letters to the Editor
Professional Surveyor Magazine - July 2010
Thank you, Mr. Estopinal, for your clear explanation of the “how to” meet the newly proposed ALTA/ACSM minimum standard detail requirements. We use Star-Net Least Squares Adjustment software, which does most of the work for us, but it certainly won’t correct a mis-aligned optical plummet, just notify that the closure is loose.
Some thoughts regarding your testing of the total station. I realize it was an example to explain the adjustment process, but this work was done for us long ago and is available today. Clark and Buckner penned “A Comparison of Precision in Pointing to Various Targets at Different Distances,” Surveying and Land Information Systems, Vol. 52, No. 1, 1992, pp. 41-45. The short version of the results is that the best target is the mark itself [e.g., nail on top of the stake], and this is closely followed by a geodetic target on a tripod, which provides great precision at any distance.
But of course the eyesight of the observer is very important. I find it personally disturbing but professionally reassuring that the young people I train to operate the instrument soon get much better closures.
A final observation from the desert: on cold winter mornings our closures are typically 1-3 seconds per station, whereas in the summer this number can easily swell to 10 seconds using a Topcon GTS 4 one-second instrument and geodetic targets.
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Where Tools Take Us
I read the interesting article
by Craig Brewer, from Savannah, on the Surveyor’s Tool Kit
: very informative. As I read through what all this remarkable STK package will do, I was reminded of some interesting survey experiences of my own.
I worked up through the ranks with the Florida D.O.T., starting in January, 1963 as assistant bridge surveyor to a great Kentuckian surveyor, J. F. Scott, long gone now. When he was later promoted to project engineer, I was given his former position as party chief and held that position until I went on the DOT training program, 1968 - 1970. Those were some good years when we laid out the control points for many I-4, I-75, and I-275 bridges in the Tampa area.
With that good training, and while working through the requirements at USF for an MA in history, I became friends with a great professor there, taking interesting courses with him. He was/is also a well-known archaeologist (Dr. James F. Strange), and in 1979 he invited me to go along on a trip to Israel as his surveyor.
That began a wonderful five-trip series of such trips to Israel, and by the second trip I had written my own set of programs for the large control traverses that we ran at different ancient sites. Using Philip Kissam’s 3rd Ed. of Surveying Practice, I wrote a set of programs for running triangulations, traverses, and more simple computations that greatly reduced our start-up time, allowing more time for logging various topo features from the multiple turn points in a typical closed traverse.
I saved those programs on cards that could be reloaded as needed into my HP-41 CV, which was a wonderful tool for the second through fifth trips to Israel. Using a Topcon EDM with those programs, we had first-order closure on all of the traverses, and from the collected topo data we drew the completed maps back in the States.
What a grand venture those trips were, and the equipment made the work so much easier than had we had to chain survey the traverses and do all the calculations by hand. So, I can really appreciate the STK that Craig so well describes in his informative article. Incidentally, I saw the first light of day about 60 miles west of Savannah, that grand ole Southern town where Craig hails from.
Steve Womble, P.E.
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Closed Lanes Means Safe Surveyors
After reading the article in the May 2010 issue, 3D Scanning: Mobile Mapping for the Interstate
, I must speak up to say that every article about mobile mapping states the same myth. While it is true that the act of mobile scanning does not require the closing of lanes or shoulders on the subject roadway, and this does in fact keep the scanner crew safe, there has been a major oversight. If you review the scanner image of the control points in your article, you should be asking yourself, "how do they get there?"
In California, Caltrans requires that the lane be closed if you are working within six feet of the traveled way. Outside of this six-foot distance, a shoulder closure is required. So while mobile mapping is truly safe, our surveyors still have to establish horizontal and vertical coordinates to these control points. In the process of setting control for mobile mapping, our surveyors must be on the highway with safety crews for likely lane closures.
The accuracies of mobile mapping that are needed for highway projects require on-the-ground control for which there is no alternative but to be on the road, and close the lanes and shoulders as needed, in the name of safety.
GJ Harmina, PLS
* * *
I know that David Gibson, over the past 30-plus years, has tirelessly promoted the growth and emergence of surveying as a separate profession, distinct from the practice of civil engineering. I applaud his efforts and, like many others, pay attention when he writes or speaks.
However, I would like to call Dave to task for, or allow him to explain what he meant by, saying that surveying was “kicked out” of its civil engineering home in the late 1950s. Yes, I have read the Grinter Report and have listened to Dave talk about the impact of that report on surveying. Warranted or not, I believe Dave draws some of his conclusions from that report. Undoubtedly, he has also accumulated additional real and anecdotal evidence to support his arguments.
Admitting some truth in what he says and writes, I’d like to offer a somewhat different perspective. I have not found CEs to be hostile but, in fact, very welcoming. Don’t misunderstand. Although I am also a licensed PE, I count myself first and foremost a surveyor. But, I have interacted with engineers throughout my career and have developed enormous respect for the civil engineering profession as well. I also believe that no profession is perfect and that we all have room to grow. We all make mistakes and we should own up to them in a responsible manner. But, I cringe when I hear anyone harping on the foibles of others. I find much more satisfaction sharing in the triumphs of joint accomplishments. Yes, that includes positive interactions with civil engineers.
In case you are looking for similar professional interaction, I’d encourage you to consider membership in the Geomatics Division (GMD) of the American Society of Civil Engineers (ASCE). ASCE has over 145,000 members, and, of those, more than 6,000 identify with the GMD. The ASCE Journal of Surveying Engineering is a successful, highly regarded, peer-reviewed quarterly publication and contains authoritative articles on many state-of-the-art issues. On another front, of late the GMD has been collaborating with the SPAR laser scanning conference organizers and offering continuing education workshops. Check out the new GMD website
. You may be surprised at what you find whether you consider it “home” or not. Licensed surveyors and LSITs are eligible for ASCE membership.
Earl F. Burkholder, PS, PE
Las Cruces, NM
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