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Presenter: David R. Doyle

Seminar Date:

Seminar Location: Fairfax, VA

Hilton Garden Inn Fairfax
3950 Fair Ridge Drive
Fairfax, VA 22033
Phone: 703-385-7774

This seminar is closed or full.


Registration:                        8:00 - 8:30 am
Morning Session:                8:30 am - 12:30 pm
Lunch (On your own):         12:30 - 1:30 pm
Afternoon Session:             1:30 - 5:00 pm

Fundamentals of Geodetic Datums

   Horizontal datums
      • Geodetic surfaces – ellipsoid and geoid
      • Positioning elements of the National Spatial Reference System (NSRS)
      • Classical horizontal positioning – triangulation and traverse
      • U.S. national horizontal datums – NAD 27 and NAD 83
   Development of satellite positioning systems
      • Foundation of space-based positioning up to GPS/GNSS
      • GPS impact on integrity of NAD 83
      • Relationship of NAD 83 and WGS 84
      • Horizontal datum transformations – NADCON, Molodensky
   Vertical datums
      • Vertical datums definitions – geodetic and tidal
      • U.S. national vertical datums – NGVD 29 and NAVD 88
      • Issues with GPS/GNSS-derived heights
      • Vertical datum transformations - VERTCON

New Geodetic Datums for the United States 2022

   Rational for replacing current geodetic datums
      • Problems with NAD 83 and NAVD 88
      • Introduction to International Terrestrial Reference Frame
      • Adoption of ITRF14 into NSRS
   National geodetic survey plans for new national datums
      • New geometric/geopotential datum definitions
      • Gravity for the Redefinition of the American Vertical Datum (GRAV-D)
      • Computing approximate horizontal and vertical positional differences
      • Importance of positional metadata

Credit Information:

Who Should Attend

  • Engineers
  • Geologists/Geoscientists

Professional Engineers
     7.0 PDHs

     Non-Credit Continuing Ed.

Continuing Education Credit Information

This seminar is open to the public. It offers 7.0 PDHs to professional engineers licensed in all states. Educators and courses are not subject to preapproval in Virginia.

HalfMoon Education is an approved continuing education sponsor for professional engineers licensed in Florida, Indiana (License No. CE21700059), Maryland, New Jersey engineers (Approval No. 24GP00000700), North Carolina, and North Dakota. HalfMoon Education is deemed an approved continuing education provider for New York engineers.

This course offers a non-credit continuing education opportunity to Virginia geologists. It may qualify for continuing education credit in other states. Refer to specific state rules to determine eligibility.

Attendance will be monitored, and attendance certificates will be available after the seminar for most individuals who complete the entire event. Attendance certificates not available at the seminar will be mailed to participants within fifteen business days.


David R. Doyle

Base 9 Geodetic Consulting Services, in Silver Spring, MD

Mr. Doyle has been involved in geodetic surveying since 1967. He joined the National Geodetic Survey in 1972 and functioned in numerous positions dealing with national adjustments, datum transformation and outreach to the surveying and geospatial community. Mr. Doyle held the position of Chief Geodetic Surveyor for 12 years prior to his retirement in 2013. He now owns Base 9 Geodetic Services which provides consultation to public and private agencies and companies as well as teaching seminars on the fundamentals of geodesy and the National Spatial Reference System. Mr. Doyle is a past president of the American Association for Geodetic Surveying, and is an active member of the DC, Maryland and Virginia professional surveyors’ associations. He has published more than 30 technical articles on geodesy and was honored as the recipient of the AAGS 2018 Joseph Dracup Lifetime Achievement award in addition to numerous other service awards from state and national surveying associations.

Tuition Costs:

Standard Tuition: $289.00
Online Tuition (pre-registration): $289.00
Group Prices
3 or more people each: $269.00

Each registration includes one copy of a manual prepared by the seminar speakers.