survey tech

Its probably vandalism, although I have seen some that were set very near roads and were damaged in that way from being hit by a car.

Its probably vandalism, although I have seen some that were set very near roads and were damaged in that way from being hit by a car.

In fact, Vegas is an ideal place for this. There are a lot of tri-stations not only in the city, but in the mountains surrounding the valley, and most of them are relatively new. Nevada, due to its remote and inhospitable expanse, was among the last areas of the country to be covered by the national control network, so most of the monumentation there is post-war era. The absence of development outside the Vegas Valley means virtually all of the points are still there. Also the markers set in the mountains overlooking the city remain safe even as the city expands. If you visit Jet, Snipe, Len, Happy, Can, Pipe, Bard, Jerk, Dodo2, Whitney2 or BMW51, you will be walking in my footsteps. BMW51 would be a good easy one to start with, its just down Boulder Hwy. from Sam's Club, unless they widened it again recently, it was close to the road 15 years ago.

They may be benchmarks, there are many different kinds of disks that have been used in various places. Its hard to tell what the initials represent, it could be some local code system.

Correct on all counts, except that there are sometimes as many as 4 or 5 reference marks. The azimuth mark was never given a number in the old days, that has only been done in recent years.

Greg The NGS data sheet for Montalto not only states that the original azimuth mark was destroyed, it also shows, in the directional data section, the precise direction to both the old one and the new one, so its clear that the new one is in a different location. Therefore, technically at least, it would be impossible to claim having found the old one. Incidentally, the new azimuth mark and the old reference marks all have their own PID, so I suppose you could report each one as a separate find, although they do not seem to be cataloged separately. I cannot explain the reason for this, its just one of the many inconsistencies to be found in the system.

Its clear from the stamping that you found Belmont. Keep in mind that the stations in this area are relatively new and were set using GPS rather than conventional methods. Therefore, the term azimuth mark has a somewhat different meaning. In conventional work, azimuth marks and reference marks are set but not occupied, so they have no precisely measured location and can only be used in conjunction with the tri-station to which they are attached. If the tri-station is lost, one of these marks may be selected and upgraded to replace it. When doing GPS however, every marker is occupied and has its own precise location, therefore any marker can be used as an azimuth mark in conjunction with any other marker. This also means that every marker has its own PID. Note that GPS 62 RM, for example, is not merely a reference mark, as its name would seem to indicate, but has its own PID. All the markers in the area appear to have been surveyed by a private firm, and its always possible that somehow the data got mixed up and the coordinates of one point are on the sheet with the description of a different point. One of them, GPS 65, appears to have been used by another firm just last year, and they do not note any problem with its coordinates. Its usually pretty easy to figure out what sort of data mix up may have occured, by simply locating all the points involved and verifying the stamping and also that the distance and direction between them matches whats given on the sheet.

This issue is not related to geocaching, so it may not be appropriate to discuss it here, but it is an increasingly common question with very profound consequences, and surveyors everywhere are obviously deeply concerned and not amused about it, so I offer the following. The short answer, of course, is yes, anyone can attempt to locate or even mark off their property lines using a handheld GPS device. However, anyone who believes it is a good way to save money, or a good idea for any other reason, is positively cruising for a bruising. Whether or not it is legally or physically possible for the property owner to do this is not the concern. The nightmare scenario arises from the consequences of either accidental or deliberate abuse of the technology by inadequately trained individuals. While I agree with the concluding sentence of the message by D&J, I cannot agree that there is "no harm" in trying the do-it-yourself method. If the person marks off a line that is actually somewhere short of the true line, that party may thereafter be required by law to respect that line, losing their rights to the portion of their own land that they accidentally excluded in marking the line. On the other hand, marking a line that turns out to be on the property of another creates an opprtunity for that neighbor to resort to litigation seeking damages against the first party for trespassing and erroneously attempting to claim a portion of their land. In any case, if any such conflict reaches a court of law and your neighbor has a document prepared by a registered land surveyor, while you have only your own personal survey results, I really hope that I do not have to tell you that you are, to put it bluntly, dead meat. So yes, you can do your own surveying, as long as you are prepared to pay several times the cost of the survey in legal fees and fines. A word to the wise - stick to geocaching.

You found somebody's property corner. The concrete post may have been the benchmark, they do not all have disks. Pay close attention to the details of the description and verify the relationship of the marker to the reference objects, if any are given, in order to make your determination. Without some verification you cannot be entirely sure.

BDT This is another case where the distinction between horizontal and vertical control points is significant. Surveyors normally provide precise directions to nearby stations, azimuth marks and reference marks, usually in degrees and minutes format, when using a horizontal control station. This is because the purpose of such a station requires this level of precision. When using a vertical control station, directions may be given using the cardinal and sub-cardinal nomenclature discussed above. This is because vertical control points have no precisely measured location and therefore the use of precise directions in such cases would be meaningless. The directions referred to may have been merely estimated by eyeball, so specifying them to the nearest degree would be ridiculous. It is a commonly observed principle among surveyors not to state results in an artificial manner, so one can generally assume that a measurement written in a precise form was precisely measured and likewise a measurement written in an approximate form was estimated. Geodetic surveyors have no use for the standard magnetic compass, since their work is always based upon true astronomic north, which often varies from magnetic north by several degress and the relationship between the two is constantly in flux due to the dynamic composition of the earth.

BDT This is another case where the distinction between horizontal and vertical control points is significant. Surveyors normally provide precise directions to nearby stations, azimuth marks and reference marks, usually in degrees and minutes format, when using a horizontal control station. This is because the purpose of such a station requires this level of precision. When using a vertical control station, directions may be given using the cardinal and sub-cardinal nomenclature discussed above. This is because vertical control points have no precisely measured location and therefore the use of precise directions in such cases would be meaningless. The directions referred to may have been merely estimated by eyeball, so specifying them to the nearest degree would be ridiculous. It is a commonly observed principle among surveyors not to state results in an artificial manner, so one can generally assume that a measurement written in a precise form was precisely measured and likewise a measurement written in an approximate form was estimated. Geodetic surveyors have no use for the standard magnetic compass, since their work is always based upon true astronomic north, which often varies from magnetic north by several degress and the relationship between the two is constantly in flux due to the dynamic composition of the earth.

Right on Rusty, I agree completely. There seem to be a number of geocachers who would like to go beyond the game idea, and this is a good way to do it. As I have said before, the people most vitally interested in maintaining control points of all types are not NGS, but the local surveyors and engineers who actually use them. NGS, in effect, planted them, like so many seeds, all across the country, but NGS has no proprietary interest in them. The fact that the NGS data sheets have been so poorly and infrequently updated over the last few decades is illustrative of this. The most complete and important records are those kept by local professionals within each community, and NGS is not only aware of this, its exactly what they intended. Those wishing to make a real contribution to their community may do just as you have said, creating their own personal record of findings and sharing it with one or more local professionals. After all, reports to NGS will do nothing to prevent surviving local markers from being wiped out by the relentless onslaught of construction development in the years to come, but working in coordination with a local surveyor one may very well be able to make a difference, perhaps even saving some markers from needless accidental destruction due to the simple lack of awareness of their existence.

Thats right, chiseled marks are sometimes big and bold, but very often they are faint and subtle, and some erode enough to become virtually invisible over 50 years or more. Some are made with a regular chisel, but many are made with a needle-like tool called a concrete scribe and can be very small.

Thats right, chiseled marks are sometimes big and bold, but very often they are faint and subtle, and some erode enough to become virtually invisible over 50 years or more. Some are made with a regular chisel, but many are made with a needle-like tool called a concrete scribe and can be very small.

An azimuth mark is a point established in a precise known direction, which provides your local surveyor with a handy reference line, when used in tandem with the tri-station. They are also very handy for astronomy hobbyists, who can use that reference line to orient a telescope, when trying to find a particular star, galaxy, quasar, nebula, etc. at a known location in the heavens. Just go to your favorite book site and do a search for "geodesy", "triangulation", "land surveying", etc. The NOAA online library also has an extensive listing of highly technical articles and treatises chronicling the development of the science over the last 200 years.

In such a case "found in poor condition" or "found damaged", followed by a complete description, including which if any reference objects remain and were used to define the location, would be most appropriate. "Destroyed" would be inappropriate, because even a damaged marker can sometimes be of use. This is particularly true of the decapitated ones, if they have a subsurface mark that remains intact. Visit the Berntsen site and note how their breakaway markers are designed. This is because property owners often destroy or move surface markers in an attempt to commit land fraud, but they do not realize they have left the subsurface portion, which the surveyor can still locate and use as evidence against them.

The reference and azimuth marks can be used by professionals to reset the true station, so it is incorrect to say they have no value. In some cases they can also be upgraded to replace the tri-station if circumstances warrant. Once again, it is important to show them the respect they deserve and not create the impression that they are disposable.

The reference and azimuth marks can be used by professionals to reset the true station, so it is incorrect to say they have no value. In some cases they can also be upgraded to replace the tri-station if circumstances warrant. Once again, it is important to show them the respect they deserve and not create the impression that they are disposable.

BDT Yes, scaled coordinates are taken from maps and are only approximate. Remember that the coordinates of a benchmark are not of any real importance, since benchmarks are only used to determine elevations, not locations. You will never see scaled coordinates on a horizontal control point data sheet, these are all precisely measured, and the old ones are just as valuable as the new ones. You may report your coordinates for benchmarks, but surveyors use the descriptions and not the coordinates to find these points, so the precision of your coordinates is really a moot point. Raouljan Yes, everyone is approved to submit data, but as many geocachers have noticed, the PS does a very indifferent job of looking for markers, often giving up far too easily and declaring them "not found", only to be found perfectly intact later by others. I would hope that geocachers, rather than merely trying to emulate their low standard, would do a much better job of seeking out and documenting points. My reference to approval was intended to support what K&S said earlier, regarding those who may be approved to submit coordinates for inclusion in the network.

Reference marks and azimuth marks are very important and should be respected just as much as any other markers, but they are technically just accessories to the true station mark. For geocaching purposes, finding any one of them might be considered acceptable verification that the geocacher was in the right area, but for official purposes it would be very misleading to report that a triangulation station was found without having seen the actual tri-station marker.

Reference marks and azimuth marks are very important and should be respected just as much as any other markers, but they are technically just accessories to the true station mark. For geocaching purposes, finding any one of them might be considered acceptable verification that the geocacher was in the right area, but for official purposes it would be very misleading to report that a triangulation station was found without having seen the actual tri-station marker.

You are right Rusty, the light is simply a temporary target that was set up directly above the point and observed when the station was viewed from some distant location at night. The reference to it on the data sheet serves to tell future surveyors that they may not be able to see the point from the ground without constucting some type of elevated target, at approximately the height indicated. I agree that it really is of no help to someone looking for the station.

BDT Some of your questions have been answered in earlier threads, but the extensive scope of what you are seeking to learn really goes way beyond what can be readily described in a forum such as this. Alot of what you are asking are things that are only learned over a long career. I suggest you make friends with a land surveyor or civil engineer in your area, who will be able to give you the most relevant and understandable answers, and perhaps show you some examples of the different kinds of points in your area. The only alternative to this would be many hours of technical reading.

Thats correct, the term "township", like many geographic terms, has completely different meanings in different parts of the country.

Yes, it would probably still be directly over the point. I have found several points over the years with tower remains around them, especially in the mountains and the desert. Check out the pictorial gallery of USC&GS history on the NOAA website, they have some pictures of both the early wooden towers and the later metal ones.