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Jul 12, 2018 · The North American Vertical Datum of 1988 (NAVD 88) is the vertical control datum established in 1991 by the minimum-constraint adjustment of the Canadian-Mexican-United States leveling observations.
NAVD 88 is both biased (by about one-half meter) and tilted (about 1 meter coast to coast) relative to the best global geoid models available today. These issues derive from the fact that both datums were defined primarily using terrestrial surveying techniques at passive geodetic survey marks.
The only difference between IGLD 85 and NAVD 88 is that IGLD 85 benchmark values are giving in dynamic height units, and NAVD 88 values are given in Helmert orthometric height units. Geopotential numbers for individual benchmarks are the same in both systems.
The North American Vertical Datum of 1988 (NAVD 88) is the official vertical datum of the United States, having superseded the older National Geodetic Vertical Datum of 1929 (NGVD 29). Both NAVD 88 and NGVD 29 are geodetic datums, a reference surface of zero elevation to which heights are referred to over a large geographic extent.
What is a geodetic datum ? What are NAD 27 and NAD 83 ? Why did NGS change from NAD 27 to NAD 83 ? How do the horizontal datums differ? Which should I use ? What is HARN or HPGN ? What are NGVD 29 and NAVD 88 ? Why did NGS change from NGVD 29 to NAVD 88 ?
The NAD 83 and the NAVD 88 are the recommended datums to use in USGS publication series information products. The use of these datums establishes a common reference for all horizontal and vertical data in the NSRS for the conterminous United States and Alaska.
What is the North American Vertical Datum of 1988 (NAVD 88)? NAVD 88 was established in 1991. In 1993, Congress adopted NAVD 88 as the official civilian vertical datum for the United States and instructed all federal agencies to upgrade to the new datum.
