Orange County's Conversion to NAD 83

Abstract

In 1987 the Orange County Surveyor initiated the conversion of its horizontal control system to the North American Datum of 1983 (NAD 83). The decision to make the transition was precipitated by the need to establish a stable geodetic network for major federal, state, and county engineering projects currently impacting transportation, flood control, and land development in Orange County. A comprehensive geodetic survey was completed using 21 primary control stations. Upon the completion of field procedures, nine control stations were held fixed, and the network was adjusted using a three‐dimensional least‐square program. Global positioning survey (GPS) technology (satellite surveying) was used to complete the geodetic network. No county general funding was used to support the conversion. The county's successful transition to NAD 83 has established a geodetic network available for county wide mapping, providing accessible control for present and future development projects, and ensuring survey monument preservation. Orange County is truly ready for 21st century surveying.