Experimental Study On Directional Observing Methods Of CPⅢHorizontal Control Network

The track control network CPIII is the three-dimensional control benchmark for ballastless track laying, operation and maintenance. Its measuring work runs throughout the phase of construction, operation and maintenance of the high-speed railway. Currently free station side-angle resection measurement is the key method of horizontal observations, and is one of the key technologies of ballastless track precise positioning. Therefore, it has necessity of in-depth discussion for free station side-angle resection measurement to explore a more streamlined measurement method.In order to provide a theoretical basis for the content which is to be studied, firstly some basic knowledge about the CPIII control network measurement is introduced in this paper, which includes the accuracy assessment indicators in shape of CPIII control network, measuring data quality control, adjustment methods and corrections, and relative mean square error of adjacent points. Then one circle measured data of CPIII horizontal control network are processed by dividing them into semiobserved datas, which will be separately adjusted with fixed points and with soft fixed points (with analysis), The statistical analysis of the results and post-precision indicators are made about corrections and coordinate differences by adjusted between one circle measured and semiobserved datas. Finally based on the precision indicators which are set in the Specification of High-speed Railway Engineering Surveying (SOHRES), the method of semiobservation in the viability of the process of CPIII horizontal surveying is judged by the CPIII re-measurement data of High-speed railway. Referring to the German high-speed railway measurement techniques, considering redunant observation component and root mean square error of unit weight as accuracy indicators of CPIII horizontal control network data processing, this paper will exploreed the measurement technical standards for high-speed railway operation and maintenance.The experimental results display:(1)In the process of CPIII field measurement, although the method of semiobservation would reduce angle and distance accuracy, it can just the same meet the SOHRES'requests, and the method of semiobservation with the telescope in normal position has the same effect as with the telescope in reveresed position. It is proved that method of semiobservation is feasible.(2)The method of semiobservation can meet the requests of surveying in high-speed railway operation and maintenance, and can be used in the process of CPIII re-measurement.(3)Some things, such as the mean redundant observation component which is greater than0.4, and the mean square error of weight unit which is greater than0.6and less than1.4, can be used as surveying technical indicators for method of semiobservation.Through the comparative analysis of the experiment between the method of semiobservation and method of observation set, the method of semiobservation can solve the problem of low efficiency at this stage of CPIII horizontal surveying, These would have a reference value for the study on CPIII horizontal surveying mothed and the accuracy estimation of CPIII re-measurement results.