Dale_Lynn Posted January 22, 2003 Share Posted January 22, 2003 I got one today that says "State Of California"... Its a "Caltreans" (highway dept) monument... It only has a name designation and year... On walkway next to is in surveyors spray chalk it say "GPS MARKER"....... Inquiring mind wants to know... Dale -------------------------------------------------------- I'm Diagonally Parked, In A Parallel Universe. -------------------------------------------------------- Quote Link to comment
+GEO*Trailblazer 1 Posted January 22, 2003 Share Posted January 22, 2003 These are the surveys done recently to adjust and get the elevations of Cities,you probably seen them walking around with their backpack GPSr There is usually 2 one takes field notes the other runs the GPSr.There have been a lot of survey catch up being done.Maybe so we do not stumble across what, is, was, trying to be done.The GPSr helps to expadite things that would have taken years.It also allows for the adjustment and refinement of the systems integration. When all else fails Geotry again. Quote Link to comment
Dale_Lynn Posted January 23, 2003 Author Share Posted January 23, 2003 I like to believe you, but the date on this marker is 1974... I think its "now" serving a dual purpose... Dale -------------------------------------------------------- I'm Diagonally Parked, In A Parallel Universe. -------------------------------------------------------- Quote Link to comment
+jeff35080 Posted January 23, 2003 Share Posted January 23, 2003 Dale, I think what Trailblazer is stating is that by going back to the original markers, their coordinates and elevations can be adjusted to make them more precise thanks to the GPS technology we now have. I have noticed that when searching for benchmarks, the ones that have been adjusted via GPS are dead-on vs. the others that haven't been can be off quite a bit based on the coordinates listed on the benchmark pages. Cheers! Jeff http://www.StarsFellOnAlabama.com http://www.NotAChance.com If you hide it, they will come.... Quote Link to comment
Z15 Posted January 23, 2003 Share Posted January 23, 2003 Many of the state marks are for their own use in highway planning/construction and many other purposes. When I was with the MDOT, we set many GPS and Bench Marks for our own use. They will not be published. They are many private companies setting GPS control points too. Its not intended for the public to use. So you may as well forget about these marks that are not shown here in the NGS database. You are just wasting your time with these. Look for the ones you info on. Quote Link to comment
survey tech Posted January 23, 2003 Share Posted January 23, 2003 The crux of the difference is that the NGS points are specifically intended for public use, whereas any points set by private companies or other agencies are a part of the specific project they were set in the course of completing and are therefore proprietary data. One could no more expect such data to be published than one could expect McDonalds to give away burgers for free. The reason for not releasing the data to the public is purely economic and has nothing to do with any desire to keep it secret. In fact the data is routinely shared between government agencies and private companies working cooperatively on all types of public projects. If you happened to know someone working for the Caltrans engineering department, for example, they could print you a list of coordinates that would keep you busy hunting for life. Quote Link to comment
+GEO*Trailblazer 1 Posted January 23, 2003 Share Posted January 23, 2003 I only meant to state that,these marks and their coordinates are still controlled by those agencies,in charge of those projects.Cost effective to me would mean that like the Executive order 12906 states,The Realease of Geospatial Information and creating the Clearinghouse,would mean that all the data is available(GIS),to the Public GPS would=(WGS 84),The reason for turning off S.A.,selective availability in the first place.If you go into a detailed analysis of the systems you will find that these (markers)Benchmarks have been adjusted(changed),or corrected however you want to put it.The reason that some,In my opinion,are hard to find or locate or have simply been removed,is because they do not meet the criteria for the listing.This is one of the reasons that I like Benchmark Hunting so well all the mathmatics are there,Original data sheets,Azimuths and Reference marks.If you do a little research you will find this correction factor to which I am trying to let others see if they can find, you just have to figure the adjustments,go by the old witness trees and the Monuments that they represent.Hint:The Magnetic Field has moved approximately 7 + degrees West since the Louisiana Purchase,The North Star has also moved West, since the,Original Field Notes, 1812-40's. When all else fails Geotry again. Quote Link to comment
+Kewaneh & Shark Posted January 24, 2003 Share Posted January 24, 2003 I've read many threads/questions in the forums (benchmarking and others) where DOT benchmarks are found by cachers wondering what they are and why they are not in the database. I think that part of the reason that they are NOT in the database may be safety. Many DOT benchmarks are within the freeway right-of-ways. Caltrans commonly puts their benchmarks on overpass bridge abutments, on on-ramps & off-ramps, and in the medians between the traffic lanes. As a government agency, the information on the DOT benchmarks is essentially 'public' information, and, like Survey Tech said, if you know (or ask) the right person, you could probably get all of the data you want on their benchmarks, but I don't think that Caltrans, as an agency, would think too highly of people stopping on the freeways and putting themselves in very dangerous situations for the purpose of benchmarking like we do it as cachers. Even surveyors who are familiar with the benchmarks, and the risks involved to occupy them, have limited, physical access to them. Generally, NGS benchmarks are/were in reasonably safe locations. This is only one possibility as to why the DOT data is not in the geocaching database and my experience is limited to California and Caltrans. Other states may have other reasoning. El Camino and Survey Tech would know more about their respective states DOTs and the admin at Geocaching.com would know why they're not listed here. Keep on Caching! - Kewaneh Quote Link to comment
Z15 Posted January 24, 2003 Share Posted January 24, 2003 People have the wrong impression of a lot of this local control. While it may be considered public domain, a lot of it is not maintained in a way the public would be able to find. Most of our control was only documented on construction plans and in Survey field notes, their is no description like the NGS datasheet so to be able to find it by a novice would be next to impossible. We did not have the manpower nor the management inclinations to maintain a database of control. Yes, some of the control is in the NGS database but those were specific projects funded with federal money and done to NGS spec's. Our programs were to build highways and transportation projects, not maintain a Survey data base. There was not organized plan to make this data accurate across the state or provide a service to the public. Our organization was controlled by engineers for engineers, surveyors were only 1/100 of the work force, maintaining a network of survey control was not on thier list of important things. Another thing is that with our org. we had construction techs using GPS to set control for projects, often this control was not that accurate to NGS spec's or only project specific such as on a old plan corrodinate systems or elevations not compatiable with current published NGS data. They often used what is called "Single Point Position" or a "3D Transformation" and only usefull to the design engineer. If you wanted to find the info you may have to file a freedom of information request and do all the research yourself. Our only obligation was to tell you were you might find the information and to let you see it. [This message was edited by elcamino on January 24, 2003 at 07:47 AM.] Quote Link to comment
+Kordite Posted January 24, 2003 Share Posted January 24, 2003 I have found several Survey Monuments mounted in the sidewalks of Pittsburgh. (You can see my noting them at my geocaching website http://www.tasigh.org/geocaching/others.html). I contacted the Department of Public Works in Pittsburgh and asked if they had a list. Their response was that they simply had no list. Their "database" consisted of stacks of cards in filing cabinets. The person I spoke with seemed to indicate that he would be glad to provide me with such a list if it existed but, as it was, the archaic filing system prevented such a thing. You might do what I have done and create a webpage of all those geogaching and benchmarking locations that aren't "official". I have some of the City of Pittsburgh markers. Also, there was a cache I visited locally (The Northern Turnpike, GCB02B) that was located at an old bridge. There are additional bridges and I plan to visit and document them before the authorities destroy them when they build an expressway through the area. Good luck, good hunting and don'tr hit your head. Kordite Quote Link to comment
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