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Details for Benchmark: JW1728

N 39° 41.600 W 079° 15.433 (NAD 83)

Altitude: 2734.31

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

Location:
In GARRETT county, MD View Original Datasheet
Designation:
SHA 228
Marker Type:
survey disk
Setting:
massive structures
Stability:
Probably hold position/elevation well.

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Found it with Dukemartin.

Found in good condition at N39 41.636 W079 15.548 with 22' accuracy.

[Photos:]
photoLocation
photoCloseup

The mark is in good condition at N 39° 41.637 W 079° 15.549.

[Photos:]
photoJW1728(SHA 228) - Garrett County MD
photoJW1728 - Looking N toward mark
photoJW1728 - Looking E on I-68
photoJW1728 - Looking W from mark
photoJW1728 - Looking S from mark

Documented History (by the NGS)

01/01/1992 by MDSHA (MONUMENTED)
DESCRIBED BY MARYLAND DOT HIGHWAY ADMINISTRATION 1992 THE MARKER IS LOCATED ABOUT 0.5 MI (0.8 KM) WEST OF KEYSERS RIDGE, 5.5 MI (8.9 KM) NORTHEAST OF ACCIDENT, AND 11.9 MI (19.2 KM) EAST OF THE MARYLAND-WEST VIRGINIA STATE LINE. IT IS LOCATED ON THE INTERSTATE HIGHWAY 68 RIGHT-OF-WAY. TO REACH FROM A POINT WHERE U.S. HIGHWAY 219 PASSES OVER INTERSTATE HIGHWAY 68 NEAR KEYSERS RIDGE, GO WEST ON INTERSTATE HIGHWAY 68 FOR 0.55 MI (0.89 KM) TO THE LARGE HIGHWAY SIGN AND THE MARKER ON THE LEFT. THE POINT IS MARKED WITH A MARYLAND STATE HIGHWAY ADMINISTRATION SURVEY DISK, CEMENTED IN A DRILL HOLE IN THE NORTH SIDE OF A 4.0 FT (1.2 M) BY 9.0 FT (2.7 M) CONCRETE BASE FOR A VERY LARGE HIGHWAY SIGN MARKING INTERSTATE HIGHWAY 68 EXIT NUMBER 14. IT IS 50.0 FT (15.2 M) SOUTHWEST OF THE CENTER OF THE EASTBOUND LANES OF INTERSTATE HIGHWAY 68, 10.0 FT (3.0 M) SOUTHWEST OF THE CENTER OF A DRAINAGE DITCH, 18.0 FT (5.5 M) WEST OF A HIGHWAY LIGHT POLE NUMBERED 10 25 250, 0.8 FT (24.4 CM) SOUTHWEST OF THE NORTHEAST SIDE OF THE CONCRETE BASE FOR THE SIGN, AND 4.4 FT (1.3 M) NORTHWEST OF THE SOUTHEAST SIDE OF THE BASE. IT IS ABOUT 4.0 FT (1.2 M) HIGHER THAN THE SURFACE OF INTERSTATE HIGHWAY 68.

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 April 1995.
  • 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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