6.8 Location and Check Survey
6.8.1 The following information shall be obtained from the designer before location:
1 List of pre-arrangement of towers;
2 Plans and sections on which the safety line of traverse to earth is drawn;
3 Location manual.
6.8.2 Before and during location,the surveyors shall inspect the terrain and surface features along the lines based on the plans and sections,and make supplementary survey and relevant modifications in case of any missed terrain or surface feature or inconsistency with the actual site.
6.8.3 The tower locations shall be set out after the stake positions and numbers of the observation station are determined.
6.8.4 Where it is impossible to erect a tower location stake due to field restrictions,the surveyors shall survey the cumulative distance and elevation of the tower location,and should survey and establish an auxiliary stake at a place which can be preserved near the tower location along the line direction.
6.8.5 Total station or GPS instruments may be used for location survey.
6.8.6 The following requirements shall be satisfied when a total station is used for location survey:
1 Location survey should be carried out one by one for the stake locations.The tower location stakes in direct routing sections may be surveyed using fore sighting method or direct and inversed telescope method in accordance with 6.3.5 and 6.3.6.The tower location stakes in indirect routing sections shall be surveyed in accordance with 6.3.8 and 6.3.9 of this code.
2 The distances and elevation differences between tower location stakes shall be surveyed in accordance with 6.4 of this code.
6.8.7 The following requirements shall be satisfied if RTK GPS is used for survey:
1 When RTK GPS is used for location survey,direct routing shall be based on the coordinates of turning angles actually surveyed during routing survey.The coordinates of turning angles and straight-line stakes or angle stakes shall be checked before location survey to ensure that the coordinate discrepancy does not exceed 7cm,and the elevation discrepancy does not exceed 10cm.
2 When the coordinates of GPS tower locations are used to calculate the values of turning angles,the tower locations at,before,and after the angle stakes shall be used.The coordinates of tower locations at,before,and after the angle stakes shall be surveyed at the same reference station.
6.8.8 The items and main technical requirements for check survey shall comply with the provisions in Table 6.8.8.
Table 6.8.8 Items and technical requirements of check survey