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Details for Benchmark: ME1728

N 41° 40.733 W 087° 59.983 (NAD 83)

Altitude: 589.46

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

Location:
In COOK county, IL View Original Datasheet
Designation:
PBM 115
Marker Type:
bolt
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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N 41° 40.730 W 088° 00.007

Spent the day with TeamFawlty seeking another bugger of a survey mark a few miles away, but we swung by here so I could nab this one. TF was very knowledgable about the bridge; though I've been by this bridge hundreds of times, I was able to appreciate its structure on a new level. Thanks, TF! The mark itself was iced over, but we located it at the above coords -- barely inside the "088".

[Photos:]
photoME1728
photoME1728 setting -- viewing ENE
photoBNSF bridge with Antique effect

Found in good condition.

[This entry was edited by Team Fawlty on Sunday, March 22, 2009 at 5:57:52 PM.]

[Photos:]
photoME1728
photoME1728-2-H
photoTHE WING WALL OF THE SOUTH ABUTMENT
This picture was taken on the north side of the drainage canal looking south to the south abutment and wing wall. You can see the second course above the ground in this picture, which is where the mark is.
photoBridge Plaque
photoMechanism for swing bridge
This bridge is an old swing bridge and part of the mechanism is still there.
photoBridge and Drainage Canal
photoTHE ATCHISON, TOPEKA AND SANTA FE RAILWAY BRIDGE

Found today at location noted in datasheet and as picture provided shows.

[Photos:]
photome1728

Documented History (by the NGS)

Unknown by CGS (MONUMENTED)
01/01/1947 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1947 AT LEMONT. AT LEMONT, COOK COUNTY, AT THE ATCHISON, TOPEKA AND SANTA FE RAILWAY BRIDGE OVER THE CHICAGO DRAINAGE CANAL, IN THE WING WALL OF THE SOUTH ABUTMENT, IN THE TOP OF THE WEST END STONE OF THE SECOND COURSE ABOVE THE GROUND, 2.2 FEET FROM THE WEST END OF THE STONE, AND 1.1 FEET BACK FROM THE FACE OF THE WING WALL. THE TOP OF A COPPER BOLT LEADED VERTICALLY IN THE STONE AND SURROUNDED BY THE LETTERS USPBM.

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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