rusty0101

quote:Originally posted by BuffaloNickel:Any of you hunt for benchmarks specifically for metal detecting? just curious! Not quite sure what you mean. Many people use metal detectors to hunt for benchmarks, I think it is even a standard piece of equipment for surveyors. Using a benchmark to do metal detecting sounds more like you are wondering if benchmarks make good tests for metal detectors. It would depend upon the metal detector and the benchmark. There are many benchmark varieties that would not show up on a metal detector, scribed marks, "stones" etc. This is not to say that benchmark medalions would be particulary difficult to find with a metal detector. However some metal detectors would treat the metal of some benchmarks as background metal and will not report it as a find. That said, I occasionally use a metal detector when searching for benchmarks in places where they may be overgrown, or covered with several inches of dirt. Have a good time. -Rusty

quote:Originally posted by SIMPSON:Finaly an explanation- This BM searching has been driving me NUTS! I went out one day to search for several and was 100% dissatisfied. The only ones I have found were by accident and then trying to log the pieces of crap are close to impossible! Any helpful hints??? SIMPSON - Bakersfield, California Take a look through the benchmark gallery, and see what some of the benchmarks you are looking for look like. They change from decade to decade, location to location, and depend upon whom places them, and for whom. You are going to be really flumoxed if you think that you are looking for some sort of medalion, and the data sheet actually specifies a nail, or scribed cross. If you use your GPS to get you to within an eighth of a mile of the benchmark, that's about as close as it will get you. Start using the data sheet to figure out what the close reference points are. Recognize that some benchmarks are not where they were placed. For a variety of reasons, some are destroyed, some are just overgrown. Some have been removed for various reasons, some legitimate (road construction for example) some illegal (vandalism). Some local references don't exist any more, or have been altered. If a road has been widened, and the data sheet specifies a distance from the centerline of one lane, the measurement will be off. That is one of the great things about doing this kind of hunting. When you find a mark, if you take good notes, you can provide feedback to the system to make it easier for the next group of people who will use these marks profesionally. Also take note of any special notes in the data sheet with respect to people to contact. If you start looking in rural areas, you may need to contact local farmers, or businesses to gain access to some benchmarks. It is also possible that you will gain some extra knowledge of the benchmark and the surounding area. Most importantly, be safe, and have a good time. -Rusty

I fully realize that my handheld GPS, while a very capable instrument for general use, is like a hand adze in comparison to a surface planer when compared to a surveyors sub centimeter GPS (I presume that this is also a dopler based gps). In other words both a planer and a hand adze will give you a surface that can be used, but the surface planer will give you such a surface much more accuratly. My question is how is a surveyors gps used? More specifically my experience with a gps is that if you are going to use it for course evaluation, you turn it on when you start, give it some time to settle down with good readings, then leave it on till you get where you want to be. I would presume that a similar situation exists for a high precision GPS. In a couple of other threads I read that surveyors start from a known benchmark with their GPS and work off of those readings. My suspicion is that a surveyor goes to that benchmark, lets the GPS aquire a stable reading, then the surveyor enters the absolute coordinates for that benchmark. From that point on, the GPS remains on, and as much as possible with open sky above it, while survey work is done. In situations where it is possible that the GPS may loose sattelite data, or the GPS reports that something seems odd, the surveyor may return to a benchmark, or local temporary benchmark to re-calibrate the equipment.. Am I far off? -Rusty

... that I am getting some of this right. Most of what I have written is based upon personal theory, conjecture and what seems to me to be common sense. Though I am fully in agreement with whomever it was that noted that good common sense is far from common. I am sure that I have made mistakes in the past, and will in the future. New question in a new thread comming up... -Rusty

Survey Tech, gurubob, or some of the other people who use benchmarks daily may have better answers, however I will give it a stab as well. There is no real "grid" organization as to why benchmarks appear at any specific location. In almost every situation, it is placed there at the decision of a surveyor who needs a benchmark for a specific task. In the example of the culvert you found, though not the benchmark as part of that culvert, I would suspect that the mark was placed as part of the construction of the water management facilities for the resivour to the west of the mark. It is possible that the mark was placed long before the road was constructed. I see no notes from the monumenting of the mark, other than possibly the details of the description that the disk is embeded in a wing wall of the culvert. Also as part of the culvert it would be useful in the construction of the road, without being likely to be disturbed by that construction. There are several factors that contribute to why a mark is established in a specific location. For example you do not want the mark disturbed for the duration of the project, or the useful lifetime of the mark. In almost all cases the mark is positioned some place where a tripod can be set over it to establish a secure "light" or laser target. That target is placed at a known or measured hight above the mark to be referenced back to the mark from other locations within the work area. I also note that the this marker is a first class vertical order marker, which means that the altitude (or at least one of the given altitudes) is considered to be very accurate, note that they give it in hundredths of a foot, meaning it is believed to be off by less than half an inch. This is useful information when establishing water control facilities. You do not want one end of a dam to be significantly lower than the other end. Likewise if you set the dam too high up into a river bed you won't get enough water behind it to make it useful, and if you get too far down the river bed you are likely to loose the dam because of heavy runoff some year. I also see that the horizontal accuracy is to within six seconds. If you have a handy straight stretch of east west, or north south roadway, find a point on that stretch that your gps says is an even multiple of 10 seconds, and walk in some direction along that road until your gps says you have moved six degrees from your starting point. You will probably be surprised at how far off from your starting point you have gone. That is one of the reasons that most benchmark hunters rarely rely upon their gps when looking for a benchmark. In almost all cases reading the description will get you closer to the benchmark than your gps will. I guess the short version is that a mark is put where the surveyor responsible for the project it is being used for believes it will do him the most good over the lifetime of the project. It has to be survivable or unlikely to be destroyed by the expected local construction activities. These decisions are entirely the responsibility of the surveyor for the project. They do have their own set of guidelines, both in relation to the federal as well as state, county and possibly city laws. Once a mark has been set, it may be used by any other surveyor who is aware of it. That is why it may end up in the NGS catalog. -Rusty

Benchmarks are natural and man-made objects useful for identifying where you are. There are several types of benchmarks. Some give you very accurate north-south/east-west location information. Some give you very accurate altitude above and blow sea-level. Some give you both, and others are useful either for finding another benchmark, or for ascertaining where true north is for a benchmark. Given that benchmarks can provide this information, they are useful in a large variety of situations. Some examples are recording right of way information for highway and railroad development. Verifying that the dyke protecting your town has sufficent hight to accomplish it's task. Confirming the boundries of you and your neighbor's properties. Helping a farmer set up and manage water runoff features for his property. Determining if your property is in the floodplane of the local streams and rivers. Monitoring erosion of river banks. Undoubtably hundreds of other activities. Before the advent of flight, benchmarks were the only way that mapping could be done. Road, geo-political and topographical maps were created with the assistance of benchmarks. With the advent of arial photography, GPS, and subsequently DoplerGPS, it is far less common for benchmarks to be used in mapmaking and other directly related tasks. On the other hand when you need to know for certain what is where, on the ground, it is often less expensive to make a few measuremnts with a laser rangefinder, a coupld of laser targets, and a couple of known benchmarks, than it is to use a DoplerGPS, which is the only one of the tools reliable enough to be used in comparison. This is becoming less true every day, and benchmarks are likely to be used less and less as the years go by, however I suspect that the ability to use the traditional surveyor's equipment, along with an understanding of the history behind benchmarks, is likely to be as much a mark of pride amoung surveyors as the ability to use a sextant and watch to determine your location at sea is to ships navigators. Then again, I could be wrong. -Rusty

quote:Originally posted by Black Dog Trackers:There are two kinds of PIDs on high structures: 1. those with an actual marker (disk, cross, PK nail, or other marker). 2. and those with no surveyors marker - just the top (finial, light, cross, etc.) of the structure. [clip] I feel type 2 is zero finding-challenge, so I just don't bother with them. My opinion is that for type 2, you can report it as a find, not only here, but to the NGS as well. I see the Power Squadron does that, so I don't see why we can't also. I like to look for the type 2 markers as there are situations where serious updates need to be made. For example, one of the church spires that I have reported was destroyed two years after it was last recovered in the NGS database. As there are two other church spires in the town that can be seen from outside of town, I felt it was important that the NGS Database needed to be updated. Part of my update on that mark was the reason for the destruction of that church spire. (No the church did not have a fire.) Another point is that many of these markers are points of interest in their own right. They generally have a history that can be fun to learn about. The county courthouse of many counties is constructed of stone locally quaried. Church Spires may be undergoing renovation. etc. I am in agreement however that searching for a benchmark marker affixed to the top of a building is generally more trouble than it is worth. For example the IDS building in Minneapolis has five benchmarks associated with it, one of them a physical disk. The other four are towers and corner beacons affixed to the building. With the high degree of security at tall building landmarks these days, I am hesitant to bother the people maintaining security here or at other buildings in the area equiped with disks. I happen to think they are important enough to warrent someone periodically checking up on them. Those I am comfortable with checking up on, I will. Those I am not, I won't. From my perspective they should be handled the same way a benchmark on any private property is handled. If you don't feel comfortable approching the owner of the property to recover a benchmark, then don't try to recover that benchmark. If you are comfortable, let them know why you are doing this, both the personal (it's a fun activity) and the professional (these markers are important to surveyors in many tasks) as you feel comfortable talking with the property owner, then act upon his request. If you don't get approval to search for the mark, don't go looking for it. -Rusty

From what I understand, the objection that National Parks management people have with geocaching is not people visiting various locations in the parks, it is the idea of leaving things in the parks. The whole idea being to leave only footprints, and take only pictures. A virtual cache should be approvable if the people running the National Parks haven't already rejected the idea of any sort of geocache on a national park. That said, a benchmark not currently in the NGS system has two advantages going for it. One being that geocache visitors did not put it there. The other being that it raises the awareness of the fact that there are other oranizations who do benchmark and who have not reported all of their benchmarks to the NGS. One thing I would recomend is that before someone posted a virtual cache that they fully document the benchmark and approach the local park management people to get approval first. Part of this is to re-assure the park people that getting to and from the cache does not present any safety concerns, and to get assurance from the park people that the random geocacher is not going to be causing park management problems. -Rusty

quote:Originally posted by gurubob:I posted this POB article to answer a friends question. I thought the little picture of the printed paper with a thumb tack would make that clear. This is a description of a survey control network that would be suitable to establish NGS monumentation. Actually you are right and wrong. But then we all are. This board is to discuss the experience of benchmarking and share knowledge. There are several recomended practices to take when posting material to this board. Presuming that you are a professional surveyor, and from the three posts you have made, only one shows some indication of that, and it is denegrating as it is, you have called that into question even in this topic. As a professional you understand that there are people who will be currious about your profession who may have no interest in persuing it as a profession of their own. There are three ways of talking to these people. One you can play the high and mighty. Two you can patronize. Three you can try to find a common ground that improves the view others have of your profession. One and two are not mutually exclusive, though three is completely separate from the others. I am a professional in a completely different field from suveying. People in my profession call upon surveyors for several different projects. Why? Because for those projects we have legal obligations that require us to confirm prior to the start of those projects, during the project itself, and at the conclusion of our projects that what we are doing falls within the regulated boundries of that project. Is it possible that I would be able to do that which we call upon suveyors to do? Sure. However it would not be legal, and I think that to do it right I would spend a long time in preparation. That said. Your post at the begining of this thread could very easily have been written at a level where people who are currious about the subject could understand what was being said. Alternatively you could have provided pointers to resources providing substantially similar information as makaio has demonstrated. My read of your original post in this thread is that you considered it to be beneath yourself to provide an explanation of how to extend a GPS network at a level that would make sense to the general public. quote: and in accordance with the FGCC guidlines with sufficient redundancy to allow for quality control is effectively long hand for saying "we follow published standard rules that lay out how to provide reliable work" I am reasonably sure that your buddy did not need the information you posted here in the form you presented. Either the information would have been better sent to him directly, or should have been re-written in a less technical form. Even the form I attempted to re-write your posting in, is outside the scope of understanding of many casual readers here. I seriously suspect that if I were to copy and paste it into one of the other forums on this set of boards that it would be above the heads of a large percentage of the readers. Again presuming that you are a professional surveyor, most of use here would appreciate finding out about your positive and negative experiences working with benchmarks while surveying. Especially when they are directly related to one of the topics under discussion. Then again, I am long winded and I am sure that some will think I am going easy on reviewing your posts. We are a community here. We welcome professionals, amatures and visitors. We are currious about many aspects of surveying, for many different reasons. I happen to be currious about how different experties work together to make the collection of activities that is going on around us function as a whole. I won't speak specifically for anyone else here. -Rusty

It can be hard to find even one of the reference marks for a benchmark at times. I know of one near me where one reference mark is in a fenced off area, and the benchmark itself is on the shoulder of a freeway. Having found the other reference mark I am happy that the remaining marks can be found, or can be recreated, even though I won't be the one doing the recovey. Life and limb considerations asside, I don't consider the mark to be found, so I won't mark it as such. That said, unless they are reporting the benchmarks as found to the NGS, it is all in fun. There is no prize for having the high count for found benchmarks that I know of. Most of us do not use benchmarks as geocaches, even if we are using them as starting points for searches. I also agree with RogBarn that once someone has found a couple of benchmarks, they are even more interested in improving their finds and search techniques. Perhaps a note like, "Glad to see you are looking for benchmarks. Just wanted to note that you reported a find on bm####, but the photo looks like it is one of the reference marks for the benchmark. Did you compare notes with the benchmark documentation and look in the area pointed to by the arrow?" would be helpful. Just my thoughts. Then again I am somewhat parranoid about my own finds and reports. -Rusty

quote:Originally posted by gurubob:once new and existing monument locations are finalized, existing NGS HARN stations and bench marks are selected as project control. Control is selected in a configuration optimized for both horizontal and vertical support of the GPS network(s) and in accordance with the FGCC guidlines with sufficient redundancy to allow for quality control evaluation and blunder detection. at least one GPS session baseline should be directly observed between each station azimuth pair. this results in uniform coordinate quality on all survey stations, an overall stronger GPS network and fewer total GPS observations. when existing NGS bench marks can not be directly occupied, a temporary eccentric point should be set at a nearby inhabitable location. conventional differential leveling techniques can be used to transfer an elevation from the bench mark to the eccentric point. This is just a stab at interpeting the above. As I am not a profesional surveyor by trade, I hope that I will learn something from this as well. Surveying projects require a set of points to provide accurate results of that project. The set of points selected are considered the project control points. Only new or existing monument locations are acceptable as control points. Additionally it is preferable that thes points have clear visibility into the gps network. (From doing ngs submissions my understanding is that this means clear sight to the sky in all directions 15 degrees above the horizon, and that the point be available to a surveyor to emplace the gps equipment to make such a reading. Flagpolls, spires and most watertowers are considered unsuitable.) It is also preferable that these points be reasonably close to the project work area, to reduce the number of gps reading required to complete the project. If for some reason a NGS benchmark is not available to the surveyor that is suitable for the project, a temporary reference point may be created close project area. To make this temporary reference point a surveyor will first calibrate the gps unit by going to one of the NGS marks and then go to the temporary reference point to take a comparison reading and based upon the difference between those two readings provide a differential reading for the temporary reference point. My presumption is that this temporary mark must be established before or at the begining of whatever project is being undertaken. Ok professionals, how did I do? -Rusty

There are dozens of questions you may be asking yourself as part of where to buy, but you should first ask yourself what you are going to use the camera for. If all you are going to do is use it for documenting benchmarks and geocaches, you will probably be happy with a vga quality camera that has a macro feature. On the other hand if you want to take pictures that you are going to make prints of, or share with friends or family, then you will probably want a higher resolution camera. 1.3 mpixel is probably too light end, 4 mpixel may be too much. 2 mpixel is about what you are looking for. For benchmarks be sure that it has a macro lense. Otherwise look at the camera, decide if you can figure out what the features are without looking at the manual, and if you understand the features you didn't spot when you look through the spec sheet for the camera. If you know what the difference is between optical and digital zoom, you probably know which you would rather have. Deciding upon where to buy the camera is a matter of comfort. If you are happy getting your camera online, do so. You are not likely to find better prices anywhere else. If you would rather shop at a discount store, Target, Shopko, Wallmart, Kmart, Alco, and many other regional discount stores all have varying qualities of cameras and sales people. If you are not satisfied with the cameras you find there, start looking at camera stores. They will cost more, however better camera stores (not necesarily the ones you find at the local mall) will have spent more time verifying that the person selling you a camera actually knows something about the cameras he or she is selling. If this is the first time that you seriously considered getting a camera, I would recomend getting a camera the same way you got your GPS. -Rusty

The newer of the two is dated 1942, and the earlier is dated 1935. The newer is from the the US Geodetic Society while the earlier is a US Costal. Based upon the two different center marks, I would suspect that the the US Costal was initially placed as a horizontal landmark giving the location a very accurate vertical height. Later on the Geodetic Society realized this was a very good location for a triangulation point, but the actual center they wanted, (perhaps for their belief in it's hundredth of a degree location) was just outside of the earlier disk, so they needed to place a new disk. It is also possible that the second crew was unable to verify in 1942 the real purpose and location of the first disk, possibly getting the information was more expensive and time consuming than simply placing a new mark where they needed one. I suspect that they were a bit rushed as they were in the process of performing some wartime development project and couldn't afford to wait for material they had no assurance would ever arrive, much less in time. I do think it is odd that the new disk has significantly darker concrete around it than the older disk. In fact the surface texture looks more like tar than concrete. Based upon that, and the fact that the original mark stamped identifier is not complete, meaning that you would have a little bit of difficulty looking it up to compare locations in the ngs database, it could even be a hoax. The part that is still visiable reads U7, based upon a label designator A####, there are only about a thousand different marks that the original marker could be. (u7000-u7999) and I could be wrong about it being a 7, it could be a 1. I suspect this one may be unique, though I wouldn't rule out others around WWII that could be close. Then again I could be wrong. -Rusty

10240 - nope already past. 12800 - no particular reason, just an idea. 14400 - a hundred gross of benchmarks. Obviously each of the thousands marks. Even powers of 2, 3, 4, 5, 8, and 16 Hmm, Jeremy, has there been any thought put forward for incentives for benchmark milestones? Sending winners a millstone would be a bit much, but perhaps web page markers of some sort for the geocacher who documents the benchmark for some milestone. After all forcing the winner to continue benchmark hunting while carying around a millstone would probably slow them down... -Rusty

I don't care how young, nimble, adventurous, or mindless you are, if the temp is below zero F, you probably are not interested in stamping around in a drift of snow to try to find a little brass medalion, when that nice warm cozy car that will take you to that nice warm house is sitting over there wondering what kind of a silly driver it has. Unless you are being paid for the privledge. -Rusty

is about as hard in most cases as opening the Yellow Pages to the construction section. From what little experience I have, there are three major, and several minor uses that surveyors have for benchmarks. Some have been superseeded by dopler gps, others have not. The primary uses that I am aware of are Road construction, including substructures such as sewers storm drains and water mains, Property borders, and Land/Water management. Some of the minor uses include Weather stations (which is why NOAA is involved) Building construction, and as noted by guru earlier flood plane determination. You may also have a county surveyor, not the canvaser type, as well as businesses in your area that strictly do surveying. Depending upon the size of the community you are in, you may have one surveyor within 50 miles, or you may have a couple dozen in the local white pages. Your yellow pages may even have a section devoted to surveyors. -Rusty

if you look at the other thread, found here..., you might note that I posted... posted October 25, 2002 09:05 PM October 25, 2002 09:05 PM It be broken... So, it did happen on the 25th. Though for people on the East coast that posting happened at 5 min after midnight, so they can claim that you are right as well. That's the problem with time zones. there are always two days involved... -Rusty

From the top of the benchmarks page: 10021 benchmarks recovered so far. Only 726404 to go! Looks like we have a winner, someone posted the magic 10,000th benchmark. -Rusty P.S. it wasn't me. drat.

If you go to one of the benchmarks, then select the link to "Find nearest : _ benchmark" it should present you with a list of benchmarks including the benchmark you are starting from. Along the right side of this table is a row of check boxes, which I believe you can select those marks that are of interest to you, and the link at the bottom of the page will download all of those benchmarks as EasyGPS records to update into your GPS. The reason I am not absolutely sure is that until either I create it, or someone else shows me where to find it, I can't make use of EasyGPS links from Linux. I have the pleasure of manually entering all the information if I want to create a bunch of waypoints for my GPS. -Rusty

This is not perfect, in that as has already been noted most track these days is continuous ribbon rail welded at it's joints, however if you are looking for a benchmark, and see that there are sections or rail bolted together, follow the tracks in the direction indicated and count off the pieces of rail. If the rail is continuous ribbon type, you will have to resort to the tape measure. You may find sectionalized track around juctions for sidings, which should approximate the original rail length for the area that sidding is in. Another thought is to be alert the next time you are on a newer bike trail that was converted from a rail line recently. You _may_ find sections of track that you can measure and use as a reference. Of course some of this may be scrap cut from original rail lengths, but if it falls into one of the lengths noted earlier, (33, 36 or 39 feet) you should have a good reference for your area. -Rusty

... they are smiling themselves away? -Rusty

We should bump past 9000 tomorrow (pst) though it might even be tonight unless the stats page is updated only daily and has happened already. The current count is two away as I draft this. Looks like the Octobers will have it, unless we loose a significant number of northern finders due to weather in the next two weeks. It's difficult enough trying to find these things in good weather, with leaves, brush and whatnot growing over them. Some of us are going to have to start contending with varying depths of snow in the montsh to come. -Rusty

First of all being on state land, you may wish to consider that placing something other than an official witness post at a benchmark may be considered littering by your states parks and recreation officers. Depending upon your state, punishment may have even harsher penalties than disturbing a benchmark. My own recomendation is to find out who "owns" the benchmark. This is usually imprinted on the mark in some way. Find out who that organization is in your area. For example a United States Coast and Geology mark may be handled by a County surveyor. A State Department Of Transportation mark may be handled by a township or county highway maintenance office. Also if you find new witness posts next to other marks in the area, they may have a sign indicating whom the local contact for this agency is. Once you have determined who should be contacted, let them know about the fact that this mark does not have a witness post as described, and offer to help them relocate the mark, or even reinstall a witness post. If you are wondering, most witness posts that I have seen in MN are highway sign posts driven to the point where approx 3 feet are above ground, then a notice sign of some sort is posted to that post. I have seen this for both Highway and USCG markers. If the description does not include a witness post, I personally recomend not installing one. Aside from the fact it can be considered littering, it may be hazardous in some locations. In states where wheat is grown, most posts that could be used as a witness post, if placed in a wheat field can caus hundreds to thousands of dollars worth of damage to harvesting equipment. -Rusty

If you are comfortable stitching images together, you can use a camera, or even a webcam as a portable scanner. I seem to recall a comercial a year or two ago where some company was selling a laptop with a webcam on a tripod where one option was to point the camera down so you could scan in documents, pictures, etc. for study later on the laptop. I would suggest using a camera with a macro lens, to get better detail. You may even consider converting each picture from raster format to vector format to make the image slightly smaller. I seem to recall that Corel draw would do that, though I do not know how well it will let you stitch together the various vector groups to build one large image. -Rusty

I would consider this to be a destroyed benchmark. The primary reason for that interpretation is that it is not in the location where it was placed, even if your GPS took you right to it, I do not think it could be used as a triangulation station, a reference mark to another benchmark, or a mark indicating the altitude of the station. As a result it does not suite any of it's original intended tasks. I think that counts as destroyed. If it is on top of, or in amoungst a pile of rocks, a surveyor is unlikely to consider it to be suitable for re-use with new coordinates, as the rocks were obviously moved at one time in the past, and are suseptable to later movement. Fields where rocks have been pulled out of, tend to grow more rocks that have to be pulled later. I seem to recall that the technical term for this is frost heaving, but I may be wrong. Condition here would be poor. Condition at NGS would need to be determined by yourself and NGS. -Rusty