PURPOSE: This rule prescribes the acceptable accuracy of first and second order control.

1. (1) The accuracy of a horizontal control station is classified according to constrained and unconstrained relative accuracy of the distance between the stations and the positional accuracy of the station relative to the known stations. The failure to meet any of the three criteria shall cause the station to not meet the classification.

2. (2) First Order Horizontal Control.

   1. (A) The relative accuracy of the distance between directly connected adjacent points shall be equal to or less than twelve millimeters (12 mm) for distances equal or less than one kilometer (1 km) and ten parts per million (10 ppm) for distances greater than one kilometer (1 km).
   2. (B) The positional accuracy of a station shall be thirty millimeters (30 mm) in urban areas and sixty millimeters (60 mm) in rural areas.

3. (3) Second Order Horizontal Control.

   1. (A) The relative accuracy of the distance between directly connected adjacent points 20 CSR 2030-18

shall be equal to or less than twenty-five millimeters (25 mm) for distances equal to or less than one kilometer (1 km) and twenty parts per million (20 ppm) for distances greater than one kilometer (1 km).

1. (B) The positional accuracy of a station shall be sixty millimeters (60 mm) in urban areas and one hundred (100) mm in rural areas.

1. (4) To fully qualify as a first or second order control station, the station must be accepted and published by the Missouri Department of Natural Resources or the United States Coast and Geodetic Survey.

AUTHORITY: section 327.041, RSMo Supp. 1993.* This rule originally filed as 4 CSR 30- 18.030. Original rule filed May 3, 1994, effective Dec. 30, 1994. Moved to 20 CSR 2030-18.030, effective Aug. 28, 2006. *Original authority: 327.041, RSMo 1969, amended 1981, 1986, 1989, 1993, 1995, 1999.