The third full week of March was proclaimed National Surveyors Week in 1984 by President Ronald Reagan. This year it falls on the week beginning March 20. To celebrate this week surveyors across the country are asked to locate a benchmark, sit a dual frequency GPS receiver over the mark, and on March 23 at 11:00 AM Central Daylight Time begin a four hour static session. The observation files are to be up loaded to the NGS OPUS Share directory. Doing this will help strengthen the latest NGS geoid model, Geoid12B.
This is strictly a voluntary effort on the part of surveyors across the United States. The Missouri Department of Agriculture’s, Land Survey Program, plans to participate. While any observation on any benchmark (on any day of the year) will help provide a stronger geoid model, there are areas of Missouri in need of attention. To date there are observations on 193 bench marks that are utilized in the geoid model for Missouri. To provide complete coverage for an area the observed bench marks need to be no greater than 30 kilometers apart. This requirement leaves some holes in the State. The largest of these holes is an area that stretches along a y-axis from Riverton in Oregon County, northerly to Berryman in Washington County, and along a x-axis from Piedmont in Wayne County, westerly to Eunice in Texas County. This area is where the Land Survey Program plans to concentrate their effort.
Another large area in need of attention is triangular and is bounded by Miller in Lawrence County, northwesterly to Eve in Vernon County, thence northeasterly to Lowry in St. Clair County, and southerly back to Miller. Observations would be helpful along strip running from Troy in Lincoln County, northwesterly through Mexico in Audrain County, to Moberly in Randolph County, with another section from Mexico, southwesterly to Hams Prairie in Calloway County. Several small sections in need of measurements are centered at Blythedale in Harrison County, Luray in Clark County, Garden City in Cass County, Forsyth in Taney County, Goodman in McDonald County, and Patton Junction in Madison County.
If you are planning on participating in this effort, please do not think these are the only areas left and that you must head to the boonies in order to participate, every observation matters. The areas listed above are areas where no observations have been made. If you are planning to participate and want to spend a day in the boonies, please think about trying to recover a GPSable (GPS is a verb, right?) benchmark in one of the above described areas.
Of the 8342* first and second order benchmarks in the MDA database only 193 have been used in the geoid model for Missouri. Please try to locate a benchmark that has not been utilized. The following links to a map showing benchmark data for the United States. Zooming into Missouri the user can see which marks have been observed and utilized in the modeling. Which marks have been observed for the model and rejected. The holes in coverage are indicated, and clicking on a benchmark will provide the user with information about the mark as well as the link to the data sheet.
If you need more information please call the Missouri Land Survey Program at 573 368 2300. Ask to speak to Jess Moss, Ron Lather, Ron Heimbaugh or Darrell Pratte.
*Not all these bench marks exist. Many have already been hit by bulldozers