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Details for Benchmark: JT9532

N 38° 06.567 W 122° 13.750 (NAD 83)

Altitude: 51.78

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

Location:
In SOLANO county, CA View Original Datasheet
Designation:
U 1393
Marker Type:
bench mark disk
Setting:
abutments and piers of large bridges
Stability:
Probably hold position/elevation well.

Must Read!

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This one is an easy find, But the cars are zooming by you. It's under the over pass. Right next to the freeway on ramp.

Found this today and this is really very busy area.

[Photos:]
photo000_0331.JPG

There are a bunch of benchmarks along the highways here that are not really practical to photograph. I've glimpsed them as we have driven by on multiple occasions, but have not tried to shoot them. Perhaps one day I will. In the meantime, I've visually verified their presence.

Documented History (by the NGS)

01/01/1987 by NGS (MONUMENTED)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1987 IN VALLEJO. IN VALLEJO, AT THE INTERSECTION OF INTERSTATE HIGHWAY 80 AND TENNESSEE STREET, SET VERTICALLY IN THE WEST FACE OF THE EAST CONCRETE ABUTMENT OF THE STREET OVERPASS OF THE HIGHWAY, 19.3 M (63.3 FT) EAST OF THE CENTER OF THE MOST EASTERLY EASTBOUND LANE OF THE HIGHWAY, 9.5 M (31.2 FT) NORTH OF THE CENTER OF THE STREET, 7.6 M (24.9 FT) EAST OF THE CENTER OF THE OFF RAMP ROAD, AND 0.9 M (3.0 FT) SOUTH OF THE NORTH EDGE OF THE ABUTMENT. THE MARK IS 1.4 M ABOVE THE GROUND.

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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