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Details for Benchmark: KU1143

N 40° 54.017 W 073° 54.333 (NAD 83)

Altitude: 172.38

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In BRONX county, NY View Original Datasheet
Designation:
N 351
Marker Type:
bench mark disk
Setting:
massive structures
Stability:
Probably hold position/elevation well.

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The mark is likely covered by a relatively fresh layer of cement. Mark not found.

Found this one while caching today. Very hard to see but I did. This was one of the toughest benchmark that I have found yet.

Found this one around midnight so was able to get up close and personal. It is a little more than half covered by the concrete wall. Still there though.

This was a tough one. The mark is on the bridge pier in the middle of this very active highway. There was no safe way to get to the setting. Furthermore, a concrete barrier had been built which seemed (from the side I was on) to cover up the lower half of the mark. I was discouraged, even though I knew it was my mark since the location was exactly as described.

I came back later in the afternoon and the sun had shifted around so now the mark was in direct sunlight. Using my binoculars I could now clearly read the "P 351" so this was a FIND after all! Also the top of the benchmark line was just visible above the concrete so this mark could actually be used for surveying.

Getting a picture was tougher. My camera only has a 3x zoom which was not too good. I took a scad of pictures and the one posted here is blown up and magnified so you can just barely read the designation. Squint.

[Photos:]
photoKU1143 "N 351", 353rd & HHP, Bronx NY
The overpass from the west side, next to the south bound lanes.
photoKU1143 "N 351", 353rd & HHP, Bronx NY
The center bridge pier from acoss the south bound lanes showing the mark's location. Note the concrete barrier comes right up to the marks.
photoKU1143 "N 351", 353rd & HHP, Bronx NY
Normal view of the mark. Estimated speed of car: 50 MPH.
photoKU1143 "N 351", 353rd & HHP, Bronx NY
Enhanced photo of mark. The designation "N 351" is just barely visible. The "3" and the "5" are easiest to see, the "N" less so, and the "1" sort of trails off into oblivion. I need a better camera!

Documented History (by the NGS)

1/1/1952 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1952 AT NEW YORK. AT NEW YORK, IN BOROUGH OF BRONX, AT RIVERDALE, AT OVERPASS OF 253RD STREET OVER HENRY HUDSON PARKWAY, SET VERTICALLY IN THE NORTHWEST FACE OF THE CENTER PIER OF OVERPASS, 3 1/2 FEET SOUTHEAST OF SOUTHEAST CURB OF NORTHWEST LANE OF HENRY HUDSON PARKWAY, 17 FEET NORTHEAST OF SOUTHWEST END OF CENTER PIER AND ABOUT 2 1/2 FEET ABOVE GROUND.
1/1/1974 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1974 RECOVERED IN GOOD CONDITION.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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