Research On Some Problems Of GPS Application In Transportation Engineering

Nowadays,large amounts of fund is poured into the construction of basic transportation infrastructure and the technical difficulties of projects are increasing, which has brought new demands for surveying: quicker speed, less investment and higher accuracy. One of heated discussions in present surveying field is how to satisfy these new demands of engineering construction timely, how to resolve some new problems that occur in the application of GPS surveying and how to exert the advantages of GPS as much as possible.Due to the problems that arise in the application of GPS technology in the construction of basic transportation infrastructure, the author researches and discusses several following facets: Firstly, according to the error character of GPS, the author brings forward two kinds of methods to improve the accuracy of the first-calculated point;He simply approaches the problem that is how to choose GPS baselines in 3D unengaged adjustment.Secondly, the author introduces several methods for the coordinate transformation and puts forward a method that be used to calculate transformation parameters by combining multi-net of GPS. In order to weaken the influence of the gross error of common points, the author introduces robust estimation and reconstructs it to coordinate transformation. Thirdly, the author constructs effective projection region by exerting functions and discusses the choice of the best projection surface and th ellipsoid. Fourthly, the author recommends the principles and methods of RTK technology and summarizes surveying accuracy of RTK technology by experimenting. Finally, the author discusses a method of acquiring height anomaly in surveying height of GPS technology. In addition, the author analyses the accuracy of GPS height by means of experiment and generalize some useful conclusions.