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st_moose

usual distance between Witness Post and Benchmark

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Is there is usual distance between a Witness Post and a Benchmark?

 

There is a witness post near my home to which I can not find the benchmark, (of course, it is still winter, so the benchmark may be under the snow/mud/leaves).

 

The nearest benchmark that shows on the geocaching page of benchmarks (which are from USGS, right?) does not show a benchmark in the area (well the nearest is 2 blocks away, which I have found.)

 

The witness post includes an address to contact the State Land Surveyor in Rolla, MO (has anyone had success contacting a state office for help with information about a benchmark?) Any suggestions where online to look for information?

 

thanks

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Is there is usual distance between a Witness Post and a Benchmark?...

 

The nearest benchmark that shows on the geocaching page of benchmarks (which are from USGS, right?)...

 

The witness post includes an address to contact the State Land Surveyor in Rolla, MO (has anyone had success contacting a state office for help with information about a benchmark?) Any suggestions where online to look for information?

 

 

Hi st_moose,

 

Since your witness post mentions Rolla, your mark must be a USGS (U.S. Geological Survey) mark. The database that Geocaching uses is a snapshot of the NGS (National Geodetic Survey) database from about a decade ago.

 

There are a large number of USGS marks that are not in the NGS database.

 

I don’t believe there is a definitive distance that the witness posts are supposed to be set back from the mark. There are always exceptions, but most that we have found are within a meter or less of the mark. The mark is often in “front” of the witness post sign, but it can also often be beside the mark or ‘behind” it.

 

The USGS does not have an online database for their marks.

 

If you find a mark that is not in the Geocaching database you can always log it at Waymarking.com.

 

Good luck to you

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Out west here, I have often seen 3 feet as the distance. But - not always...

Edited by Klemmer & TeddyBearMama

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I see a lot of 3 foot spacing, some 1 foot, and quite few apparently random distances. The sign post will usually be further from the road than the disk, and often in the fenceline if there is/was one.

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Is there is usual distance between a Witness Post and a Benchmark?

 

Here in South Carolina, it's almost random. Some are within a foot, and sometimes some are 75 feet or more. The only thing I have discovered is if the post is one of the old metal ones, it's always within a foot or two. The orange post is a wild guess.

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Usually a few feet.

I have seen cases where the witness post is 15-20 feet away.

I have also seen cases where the mark was (apparently) destroyed, but the witness post survived.

I have also seen cases where the witness post was (again, apparently) removed while construction went on and then replaced...but the mark was destroyed by the construction.

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From the USC&GS “bible of triangulation”, Special Publication No. 247, “MANUAL OF GEODETIC TRIANGULATION, page 89:

 

“8. Witness posts.--In order to aid in the preservation and to serve as a means of easy recovery of the monuments being established, a wooden post will be set adjacent to the concrete station monument or near one of the reference marks at each station, preferably at the station mark. This post shall be 4“x 4” in cross section, about 3 1/2 feet in length, and shall be set to project 15 to 18 inches above the ground surface. The top should have a 1/4 to ½ inch bevel. It shall be painted white and shall have lettered thereon in black the legend “U.S. (triangle)” or U.S. (triangle) R.M.” These posts will be set for monuments established along public highways, in rural districts, along the rights-of-way of railroads, and along the shore lines of rivers and lakes. They need not be set for monuments established along business streets, in residential sections of cities, on the grounds of schools 2nd churches, in cemeteries, in cultivated farm lands, or on bare mountain tops. For survey stations established in cultivated fields and marked with an underground mark, the post shall be set at a reference mark."

 

This publication was updated in 1959. Since then Witness Posts were changed to metal signs on metal posts, and more recently to fiberglass posts with labels.

 

GeorgeL

NGS

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Is there is usual distance between a Witness Post and a Benchmark?

 

I have found them and set them from 0 ft to 50 ft of more from a mark. I found a NOS driven rod and the witness post was some 60 ft away. The mark was in an open lawn below the sod and the witness post was along a fence.

 

Its funny how some of those wooden witness posts can survive 60 yrs and more. I have found them where your can still read U.S.B.M. stencil on the faded white post. They the next mark 1 miles away the post is completely rotten away.

Edited by Z15

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We were going to look for this one yesterday, but it was off in a pasture that we didn't want to trespass in. According to the datasheet, the witness post is 230 feet away from the disk. :lol:

 

CQ2703'DESCRIBED BY LA DEPT OF HIGHWAYS 1966 (JB)

CQ2703'THIS STATION IS LOCATED ABOUT 4 MILES NORTH OF THE CHOUDRANT

CQ2703'OVERPASS AND INTERCHANGE ON INTERSTATE 20, ON LAND OWNED BY

CQ2703'E.D. BROOKS. STATION IS SET IN TERRACE ROW IN PASTURE, 385.16

CQ2703'FEET SOUTHWEST OF A FENCE CORNER NEAR A GROVE OF PECAN TREES,

CQ2703'428.10 FEET SOUTHWEST OF A FENCE CORNER NEAR A GRAVEL ROAD

CQ2703'RUNNING NORTH, 269.82 FEET SOUTHWEST OF A TELEPHONE POLE

CQ2703'NEAR SAID GRAVEL ROAD, 230.20 FEET WEST OF A METAL WITNESS POST

CQ2703'AND SIGN SET IN FENCE ALONG SAID GRAVEL ROAD, AND 260.20 FEET

CQ2703'NORTHWEST OF NORTHWEST CORNER OF FRAME RESIDENCE FACING SAID

CQ2703'GRAVEL ROAD.

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Most of the ones in Alberta (Canada) are 30cm, but not always. Oftem I see GP(they are called guard posts here) with no servey marker, or servey markers with no GP.

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