Z15

Actually there is a manual the decribes this. For Triangulation stations, travese etc " C&GS Special Publication 247. Manual of geodetic triangulation by Gossett, Franklin R., January 1950, 344 p., $25.00. For leveling (Bench Marks) NOAA Technical Report NOS 73 NGS 8. Control leveling (supersedes C&GS Special Publication 226) by Whalen, Charles T., May 1978, 20 p., $1.90. NOAA Manual NOS NGS 1. Geodetic bench marks by Floyd, Richard P., September 1978, 50 p., $3.40. NOAA Manual NOS NGS 3. Geodetic leveling (unbound, supersedes C&GS Special Publication 239) by Schomaker, M. Christine, and Berry, Ralph Moore, August 1981, 209 p., $16.30. Here's a link to NGS Publications in PDF format. If you can't read that than you will have to requuest Geodetic Charting and Publications booklet as shown on this page. [This message was edited by elcamino on January 14, 2003 at 05:02 PM.]

Marks in building are sometimes a challenge. I can recall 2 BM's we recovered. One was in the side (set vetically) of an old brick bldg. When we followed the decription to the location you could see the bldg was now covered with a wood and metal siding. As I walked over to the location, I notices a hole in the siding. I looked and there was the disk about 4 inches in. Another one, the guys were doing recon and could not find a BM that was in all old schoolshouse (from 1934) out in the country. They said the bldg was there but no disk. So we went to look at it again one day and this lady pulls up in the driveway (was now a home) and asked what we wanted. I showed her the data sheet and she says, there's something like that inside my house? Sure enough, they had added on to the old school many years ago before she owned the house and inside garage was the disk, still set in the wall. The addition looked original. She always woundered what that was for. We were able to level to it.

When you see a scaled position it means that someone (the team setting the mark originally) plotted it on a USGS quadrangle map and interpolated its position from that. I talked with a NGS leveling recon team in 1996 (part of my job). They were leveling to CORS sites and Harbors of refuge on the Great Lake's. I saw the map they had with all the existing marks plotted as well as the new ones they were setting along thier lines. They did not have any hand help GPS units.

One thing to note. Not all those that use the marks are surveyors in the true sense of the word. My former employer had construction engineering techs that would always set BM' for road work. Very few of them cared or new much about the NGS marks. (fyiwe had 1 sruvey tech and about 25 engr techs in our region). They would drive a RR spike into anything, assume some bogus elevation and go from there. We constantly had problems with the way some these guys would do things. Most all of these techs had 2 yr civil technology degree's and new enough about surveying to be dangerous. We constantly were having to explain to people that what they did only served thier purpose on a single project and should not be taken as gospel. We even had occasions when we ran levels for the project only to have the engineering techs still asign some assumed elevation to our marks. Constant battle between the P. Surveyors and the Civil Engineers (Project Engineers) who only cared about getting the job done, no matter what. They often never protected or saved valuable points like, sections corners, plats, BMS and USGS marks etc. We had to always be one step of ahead of them and were GPS'ing all control into the Mi Coord System. Contractors were another problem and often wiped out the marks.

I have a different take on this. While the adjusment was made in 1991, this does not mean is was leveled accross again. This is probalby the 1988 NAVD adjustment. What you found could be anything and you can't assume the survey disk and the rr spike have anything in common. Someone could have looked for that mark, found where they thought is was and roughly transferred an elevation over to the spike to use and that was it. As a matter of fact I have done that very thing in the past when working for the DOT. There was a BM is the top of a culvert headwall and the headwall was raised higher, burying the disk. You could see the seam in the concrete. Our hydraulics engineers needed the river/new bridge survey to be based on the NAVD88 so ww had to come close to this elevation because there was no other BM in miles to use, besides being told to do so by the Survey Chief (PS)!

Yes this is good. Let everyone know its not the same. 50 yrs from now it will be helpfull.

quote:Originally posted by Tacguy:" ALUMINUM TABLET, IN VOLCANIC ROCK. " Too bad you didn't have the info to log this one, I would like to see an aluminum tablet! I have not seen a description of this before; an aluminum rod, yes, a TABLET? Cool! An aluminum tablet is another term for a Survey Disk. Its what they called them in the old days at USGS. Seen many of them in the past.

About the only leveling NGS is doing now is for special projects. My former employeer (retired from MDOT) is doing leveling for NGS. I think they (NGS) only have 1 or 2 leveling crews left. They were in my area in 1996 leveling to harbors of refuge and the US Coast Guard CORS site, see Portage A, S 346. I talked with the recon team and provide some info to then to locate some control. It was a 2 man team with a 4X4 utility truck, a permanent NGS tech and college intern. The leveling party had a 4X4 suburban and 2 motorbikes for the rodman. 2 NGS techs and 2 college interns. The rodman used the motor bikes to move about and the instrument man road on the running board of the truck. They cover a lot of ground in one day leveling. They needed 3 existing BM's to start the leveling from o each line they set here in 4 different locations around Lake Superior. [This message was edited by elcamino on January 01, 2003 at 05:24 PM.]

I would log it as not found with a note to the effect, that you found a concrete post that fits the desecirption but no survey disk. Thats, if you are certain of the facts. Was there evidence of vandalism?

Asside from the coords, did you use any of the references from the data sheet to locate it? Sounds like you may not be in the correct location. The GPS coords from your receiver allthough appearing correct could be off by as much as 100 meters. Its a false assumption that your handheld reciever is any more accurate to + or - 100 meters unless you are trackign WAAS sats. So, I would forget the coords and use the refenerences given to look for it. It only suppposed to be 5 cm (2 inches) below the ground surface.

Well, the use materials is up to the agency/surveyor setting the mark(s). Like most things, you have choice of many different materials. Steel rods as the lowest cost, aluminum is more expensive and stainless steel is the most expensive. Its usually boils down to cost. For instance I worked for the MDOT for 31+ yrs, one of our survey chiefs (I worked for 3 different) insisted we use 3/4" aluminum Bersten rods driven a minumun of 9 ft (below frost in this area), while another was alwas concerned with cost and would only use concrete posts or disk set into permanent objects (rock, bridges etc), even though we could prove to him using the driven rods cost less due to effort to construct. Other agency's were using concrete (for cost reasons only) so he would also. My crew of 2 could set 6-8+ marks in one day while his crew could only manage 2 or 3 because this had to hand dig the holes 5 ft deep by 12" dia. to meet, all we had to do was to use the gas driver and hammer them in, dig away the top 2 feet and install the PVC pipe and cover, most would take about an hour. If you will notice there is a statement on the data sheets about the magenetic condition of the mark. They need to know if anything magnetic at the mark, for gravity surveys and other things they may want to do in the future that could be affected by this. You know what can happen to computer disks and anything magnetic? While iron seems reliable, it is not for precision control. Iron will corrode, then attach itself to the surrounding ground and move with the frost (if you have frost) or the surrounding earth. What you may have found what you assumed was all iron (Steel) was proboably in fact copper coated steel rods. These were a low cost alternative to stainless steel and concrete but we tried to get these but no one is suppling them, we went with alumunum and it still cost about $9/3ft. Anytime you deal with professionals (Engineers are the worst), there will always be a difference of opinion of how things should be done. We had a term we used amoung outselves, "Why do it right when we can do it wrong" [This message was edited by elcamino on December 23, 2002 at 07:03 AM.]

To be able to locate in the future with a magnetic locator. If the magnet is there, its because the rest of the materials are non-magnetic, i.e. rod is aluminum or stainless steet.

Another, got a laugh when I read the last paragraph. TRILOBA USLS 1873 [This message was edited by elcamino on December 18, 2002 at 06:26 AM.]

L@@K in ebay

From prior experience the best way to ship would be thru the mail. I sent a calculator to Germany from USA and it was easy. If you go any other route, UPS or FedEx the paperwork will be a nightmare.

Can you provide a link to one so I can take a look at what you are asking abut? "O" Party is referring the "Observation Party". Team of guys that did the Survey work. Another thing you will often see in these old descriptions is, "Center of L.O.T.". This had me baffled for years till one day we were looking for a Triangluation station and you could still see one of the remaining Fire Lookout Towers in the distance.

31.5 years as a Survey Technician for the MDOT. USGS - U.S. Geological Survey Dept of the Interior NGS (Formally USC&GS)National Geodetic Survey, agency of NOAA, Dept of Commerce There are countless federal Agencies (and State)who have survey control out there. NFS (Nat'l Forsest Service) Interior FAA (Federal Aviation Admin) Transportation USCE (US Army Coprs of Engineers) USLS (US Lake Survey), NOS (Nat't Ocean Service) to name a few.

The differnce between the HARN and CORS is that you have to physically occupy the HARN stations whereas the CORS are permanently occupied and you just need to download the data to match your survey. Since the CORS are running 24/7, it can be determined how stable the positions are, whereas the HARN's are existing (for most part) horizontal and vertical control marks that are subject to movement from frost, construction activities and vandalish. Depending on the amount of CORS in your area, it can be much quicker to use CORS data. I know we used HARN for a while but when our CORS went online, we saved a lot of time by using the CORS data in our highway improvment Surveys. In 2001 we reobserved our HARN when we positioned our CORS stations.

T.T. 8xx 1932 This is a US Geological Survey mark. It may or may not be a Bench Mark. TT designates it as part of the "Transcontiential Traverse". So its a horizontal control mark first, if USGS ran levels over it and it does not show up in the NGS database, only USGS will have the info. Not all USGS were also used by NGS (USG&GS).

Those are history, they don't do triangulation anymore. To time consuming and costly. GPS has made that obsolete.

OK When they did the survey that established this point, the used towers (up to 100+ ft in the air) to see over the tree's etc. They did most all of the observations at night because there were less visibility problems. The targets were 6 volt latern lights and that is how far the light was above the ground. If you will notice, above the guys and out of sight is where the light would be on a typical tower and there is a light on the platform. "O" party means Observation Party. Notice the guy sitting in the photo, has one arm. Must ahve been a climb for him, nowadays he would sue for them to build him a ramp up there. They did triangulation survey in Michigan back in the 1977-78 that used these towers. Our Dept. (MDOT) cooperated with NGS by supplying men and vehicles. They wanted volunteers to work on the towers but I would not to climb 100 foot towers and stay up there for 4-6 hours. survey crew in action [This message was edited by elcamino on December 15, 2002 at 08:40 AM.]

I use (now retired) to use these a lot in our Surveys. We would set up our 3 GPS receivers to run for 5.5 hours collecting data. Then send the data to OPUS and get back state plan coordinates on our survey points. This example is a little jumbled up do to formating that does not work in this page. I can't get the font to print right so the data is more legible??? From: To: Subject: OPUS solution : 22011830.02o Date: Tuesday, July 23, 2002 8:50 PM NGS OPUS SOLUTION REPORT ======================== USER: mraff@chartermi.net DATE: July 24, 2002 RINEX FILE: 22011830.02o TIME: 00:50:14 UTC SOFTWARE: page5 0203.19 ./master.pl START: 2002/07/02 11:39:00 EPHEMERIS: igs11732.eph [precise] STOP: 2002/07/02 17:48:00 NAV FILE: brdc1830.02n OBS USED: 10574 / 11285 : 94% ANT NAME: LEIAT502 # FIXED AMB: 117 / 130 : 90% ARP HEIGHT: 1.629 OVERALL RMS: 0.025(m) REF FRAME: NAD83(CORS96)(EPOCH:2002.0000) ITRF00 (EPOCH:2002.5003) X: 159300.868(m) 0.021(m) 159300.230(m) 0.023(m) Y: -4451619.426(m) 0.046(m) -4451618.095(m) 0.047(m) Z: 4550009.296(m) 0.039(m) 4550009.246(m) 0.039(m) LAT: 45 48 0.94203 0.008(m) 45 48 0.97232 0.009(m) E LON: 272 2 58.02238 0.020(m) 272 2 57.99507 0.031(m) W LON: 87 57 1.97762 0.020(m) 87 57 2.00493 0.031(m) EL HGT: 295.048(m) 0.060(m) 294.068(m) 0.061(m) ORTHO HGT: 329.507(m) 0.065(m) [Geoid99 NAVD88] UTM: Zone 16 NORTHING: 5072294.885(m) EASTING: 426132.463(m) SPC: Zone 2111(MI) NORTHING: 113469.186(m) EASTING: 7926109.134(m) BASE STATIONS USED PID DESIGNATION LATITUDE LONGITUDE DISTANCE(m) AF9550 kew1 UPPER KEWEENAW 1 CORS ARP N471337 W0883727 166820 AF9553 stb1 STURGEON BAY 1 CORS ARP N444743 W0871851 122314 AJ5569 sup2 ESCANABA CORS ARP N454458 W0870424 68449 NEAREST NGS PUBLISHED CONTROL POINT AA5210 22203 N454820 W0875932 3287 This position was computed without any knowledge by the National Geodetic Survey regarding the equipment or field operating procedures used. [This message was edited by elcamino on December 13, 2002 at 06:28 PM.]

A GPS CORS is a Continously Operating Reference Station. It runs 24/7 collecting GPS data and making it available to the public for varous use, Surveying, Navigation, etc. Follow this link for more info NGS CORS CORS Map CORS Site [This message was edited by elcamino on December 13, 2002 at 06:07 PM.]

heres' a deal ebay

Hmmm mraff@chartermi.netEmail me with any offer. I will toss in a new Delorme GPS receiver.. New, never used. Has RS232 serial cable and USB adapter to hook up to a notebook computer. None of this equipment was ever used. [This message was edited by elcamino on December 13, 2002 at 12:39 PM.]