The Establishment Method And Precision Analysis Line Engineering Survey Coordinate System's

At present,when the domestic massive construction projects are in construction, a variety of major projects such as railways,highways, bridges, etc,have been started, because of the disadvantages of the conventional measurement techniques and GPS itself, making the GPS in the use of large-scale projects became more and more popularity.As the line project's control network due to the features of line,and the special of GPS's application in bridge engineering, In this article we will use Pakistan's Karakoram highway reconstruction project as an example to study the following questions:1)The transformation of the WGS-84 geodetic coordinate system,the coordinate system commonly used in China and the local coordinate will are disscussed, as well as lay the foundation for subsequent engineering,GPS measurements use the WGS-84 coordinates, and in engineering practice is used in local coordinates.Commonly used in China is Beijing 54 coordinate system and Xi'an 80 coordinate system, GPS measurement results should be converted when using in engineering practice.Therefore, the paper discuss the differ and the transformation of the engineering survey coordinate system commonly used in national and CGCS2000 national geodetic coordinate system in detail.2)GPS data processing are discussed in detail in the process.3)The measurement programs of the project was studied out combined with the reconstruction project of Kalakunlun highway.It mainly target at how to eliminate the deformation of projection length,and to improve the accuracy of the measurement, provide a similar reference in line measurement.