Accuracy Of Surveys

Surveys for Categories I, II, and III as defined below must meet the minimum accuracy requirements provided below for the category where the survey is located. The category must be determined by the Land Surveyor to the best of his knowledge and belief at the time of the survey. Nothing in this rule shall preclude a Land Surveyor from using a greater degree of accuracy than that required as a minimum for any category provided below. (1) Urban and Subdivision Property Surveys (Category I). For Category I surveys in Tennessee, the angular closure shall not exceed fifteen (15) seconds times the square root of the number of angles turned. The linear error of closure shall be equal to or less than 1 foot per 10,000 feet of perimeter of the lot of land (1:10,000). When a land parcel of one (1) acre or less is encountered, the allowable error shall not exceed one tenth (1/10) of a foot of positional accuracy at any corner. (2) Suburban and Subdivision Property Surveys (Category II). For Category II surveys in Tennessee, the angular error of closure shall not exceed twenty-five (25) seconds times the square root of the number of angles turned. The linear error of closure shall be equal to or less than 1 foot per 7,500 feet of perimeter of the lot of land (1:7,500). When a land parcel of one (1) acre or less is encountered, the allowable error shall not exceed one tenth (1/10) of a foot of positional accuracy at any corner. (3) Other Property Surveys (Category III). For Category III surveys in Tennessee, the angular error of closure shall not exceed thirty (30) seconds times the square root of the number of angles turned. The linear error of closure shall be equal to or less than 1 foot per 5,000 feet of perimeter of the lot of land (1:5,000). When a land parcel of one (1) acre or less is encountered, the allowable error shall not exceed one tenth (1/10) of a foot of positional accuracy at any corner. STANDARDS OF PRACTICE CHAPTER 0820-03 (4) Remote Sensing Surveys (Category IV). For Category IV surveys in Tennessee, it is acceptable practice to incorporate the use of Global Navigation Satellite Systems (GNSS) equipment into any survey. The precision of all measurements made with such equipment must, at a minimum, meet all precision standards required otherwise by the rules under Chapter 0820-03. GNSS surveys performed to provide control networks shall be performed in such a manner to obtain a ninety-five percent (95%) confidence level of the positional accuracy of each point relative to the published positions of the control points used. (5) Differential Leveling Surveys. The surveying process in which a horizontal line of sight of known elevation is intercepted by a graduated standard, or rod, held vertically on the point being checked (does not apply to Trigonometric or GNSS surveys). (a) Urban Differential Leveling Surveys. Leveling employed for commercial, industrial, or urban land surveys shall be executed with an error of closure (Y) not to exceed in feet. 0.5 Y = 0.04 (M) (Y equals 0.04 times the square root of M) Where Y = discrepancy in vertical measurement (in feet) and M = distance from datum reference (in miles). (b) Other Differential Leveling Surveys. Other leveling surveys shall be conducted with an error of closure (Y) not to exceed in feet. 0.5 Y = 0.10 (M) (Y equals 0.10 times the square root of M) Where Y = discrepancy in vertical measurement (in feet) and M = distance from datum reference (in miles). (c) Agreement for Leveling Surveys. Prior to any type of Leveling Survey, including control for photogrammetric mapping, the Land Surveyor may determine and set forth in a written agreement with his client to perform a more accurate Leveling Survey and the general procedure to be employed.