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Details for Benchmark: DC0901

N 32° 43.483 W 117° 10.233 (NAD 83)

Altitude: 26.22

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

Location:
In SAN DIEGO county, CA View Original Datasheet
Designation:
U 734
Marker Type:
bench mark disk
Setting:
light structures
Stability:
Mark of questionable or unknown stability.

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Looked around, got some strange looks and did not find the marker.

As the NGS record indicates, the current concrete base for the signal appears not to be the original one. The mark is no longer present, and I very much doubt it was simply covered up or otherwise replaced.

Documented History (by the NGS)

01/01/1944 by CGS (MONUMENTED)
01/01/1955 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1955 AT SAN DIEGO. AT SAN DIEGO, 0.7 MILE NORTH ALONG THE ATCHISON TOPEKA AND SANTA FE RAILWAY FROM THE UNION STATION, AT THE GRAPE STREET CROSSING, IN THE TOP OF THE NORTH CORNER OF THE CONCRETE BASE FOR AUTOMATIC SIGNAL 10710B, 47.9 FEET SOUTHWEST OF THE SOUTHWEST RAIL OF THE SOUTHWEST TRACK, 1.7 FEET SOUTHEAST OF THE SOUTHEAST CONCRETE CURB OF THE STREET, AND ABOUT LEVEL WITH THE TRACK.
01/01/1970 by CA3260 (GOOD)
RECOVERY NOTE BY CITY OF SAN DIEGO CALIFORNIA 1970 RECOVERED IN GOOD CONDITION.
01/01/1978 by NGS (MARK NOT FOUND)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1978 CONCRETE BASE FOR SIGNAL DESTROYED.
01/01/1987 by NGS (MARK NOT FOUND)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1987 NOT RECOVERED.

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 May 2000. * This is a READJUSTED BENCH MARK height. Code A indicates a distribution rate of 0.0 thru 1.0 mm/km. The height was derived from older observations constrained to new heights in a crustal motion area. The height is approximate in relation to other heights in its vicinity.
  • 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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