Surveyors Information - Geodetic Control Data

Geodetic Survey Control For Maryland

Information on permanently monumented control points including horizontal control, vertical control, HARN stations, Calibration Baselines and retrieval software can be obtained from the NGS web site or from the NGS Data Center on CD ROM. The Data Center may be reached at 301-713-3242. The cost of the CD is $50.00 and covers all of the Northeast United States.

Maryland HARN

psd_harn graphic

The map above shows the location of High Accuracy Reference Network (HARN) points in Maryland. The position of these points was determined by GPS observations and have a stated accuracy of 1.0 to 0.1 parts per million.

Calibration Baselines in Maryland

psd_baseline graphic
The map above shows the approximate location of the six calibration baselines located in Maryland. A calibration baseline consists of a set of very stable survey monuments which are accurately measured using specialized equipment. By comparing their results with the values published for the monuments, surveyors are able to verify the accuracy of their equipment.





Aberdeen CBL

Harford County, Md.

39 29

76 10

Cambridge CBL

Dorchester County, Md.

38 35

76 08

Hagerstown CBL

Washington County, Md.

39 43

77 44

Howard County CBL

Howard County, Md

39 15

76 56

Leonardtown CBL

St. Marys County, Md.

38 19

76 33

Pittsville CBL

St. Wicomico County, Md.

38 23

75 23