【正文】 esign documents, and the site standard point, conductor piles and crossing point piles shall be clearly identified according to the design drawings. within the measurement of signs, must take appropriate protection measures. on the measurement of the end, it is necessary to emphasize the protection of pile position, that is, in the design unit after pile, should be timely use of brick piers or pouring cement pier and other methods to be protected, so as not to lose. these piles are generally farmland or residential areas, it is easy to be manmade destruction, and once destroyed, let the survey and design units to fill test, then delay the construction, but also increase the cost.midline retest and edge loftcenter line measurement is based on the alignment measurement, the road center line plane position on the ground marked in detail. it is the difference with the alignment measurement is: alignment measurement, but the intersection of the road and the straight line segment of the necessary turning point marked out, and in the midline measurement, according to the intersection and the turning point with a series of stakes will road straight segment and curve segments are specified in detail on the ground.the alignment survey is usually carried out by the survey and design units, and then the pile and measurement results to the construction side, the construction unit by the middle line and construction measurement.subgrade construction should be fully restored before the center line, according to the restoration of the pile in the road and the relevant provisions of the roadbed side of the pile. on the midline remeasurement and edge lofting, should pay attention to the following points。one should pay attention to the distance between the intersection, the direction is consistent with the drawings。 such as an engineering project has several tenders, should pay attention to the center of the adjacent tenders are closed, midline measurements should be indepth adjacent tenders 50 ~ 100 m。 attention should be paid to the center of the structure such as bridge and culvert is closed。 should pay attention to the relative position of the building and other buildings and drawings are consistent. if you find problems in a timely manner to identify the reasons for the design unit.second, retaining pile set. it is very important to set up pile protection pile in the middle of the road, but these piles are easy to be destroyed during the construction. therefore, it is necessary to carry out the restoration and surveying work of the middle pile during the construction of the roadbed. in order to quickly and accurately restore the center pile in the original position, must be on the road before the construction of the main control point of the pile such as the intersection point, turning point, curve control points set up retaining pile. the socalled retaining pile, is outside the scope of the construction is not easy to be destroyed where some stakes set ing to these pile, with simple methods (such as the intersection point, range, etc.), you can quickly restore the original pile point.set the pile should pay attention to the following aspects: in each straight section of the road, at least three control piles to set up retaining pile, so even if there is a control pile can not be restored, the other two points can be used to restore the straight section to the original position。 the intersection angle of the two direction lines as close as possible to 90 176。, should not be less than 30 176。 angle of intersection。 retaining pile should be selected outside the scope of construction, but not too far away。 pile distance can not be too far。 the retaining pile must be solid and reliable, pile to facilitate the erection of measuring instruments and observation.set up retaining pile of curve side. for the curve segment, because of the more difficult to determine the side of the pile, remeasuring timeconsuming more, so after a precise line, the edge of the curve section of the pile pile should also be set representative pile, which can reduce repeat the measurement, reducing the measurement workload.third, the laying of mileage pile. after the midline pile is fixed, it is possible to lay out the control pile of the mileage pile on this basis. mileage pile layout principle is: in the straight section, generally arranged in every 100 meters of the entire pile of crosssection, similar to the mon road construction 100 meters pile layout。 in the curve section of the pile to be properly encrypted, in the curve mileage pile can be large stakes, above the mileage mark with paint or ink station, into the road outside the scope of construction on both sides of the ground, it is best to play on each side of a . to ensure that the construction is not easy to damage the case, from the embankment edge should be as close as possible to facilitate the use, generally 1 to 2 meters.the laying of mileage piles is not addressed in most of the surveying and settingout sections of the construction manual, and is not taken into account at many sites. i found in some sites, some construction technicians in the construction survey, the determination of the distance station is a long distance from a foot a foot row over, not only a waste of time and prone to cumulative error. if the mileage stakes are not allowed, then the elevation, slope quality control is out of the question.third, the proofreading and additional standard pointfirst, the use of design units set up before the standard point should be carefully checked, close the gap may not exceed the limit, such as exceeding the allowable deviation should identify the reasons and promptly reported to the relevant departments. the design unit delivers the leveling points normally set several months ago. these points in the field can easily be manmade collision or natural subsidence due to the ground changes, so be sure to carefully review before use。 se