Based On Google Earth Data Source Plane Alignment

Owing to the lack of terrain data sometimes, highway location design has difficulty in the pre-feasibility stage of highway construction. Therefore, it is necessary to put forward a new method for highway location, which uses the existing Digital Earth technology—Google Earth to obtain terrain data. In order to reduce the workload of designer and improve the automation of route alignment, an automation optimization method for horizontal alignment is analyzed in this paper. Relevant research and findings are as follows:(1) The application status quo at home and abroad of Google Earth has been analyzed, which is as the representative of the Digital Earth; Proposing that Digital Earth—Google Earth be used as a platform of highway location design; Introducing systematic design targets and work flow and the required computer technology of the platfom.(2) Google Earth COM API has been used for realizing terrain data acquisition in selection area from Google Earth quickly. Statistical analysis of data precision was implemented by comparing the data downloaded from Google Earth with measured data of projects, which drawed the conclusion that the accuracy of terrain data obtained from Google Earth meet the required precision of digital terrain data in the pre-feasibility stage of highway location. In addition, treating the download data with coordinate conversion and mixed surface model, the digital terrain model based on Google Earth terrain data was established. Experiments show that the digital terrain model can be matched very well with the images displayed by Google Earth platform, and it has relatively high accuracy.(3) A mathematical model of horizontal alignment optimization was established. In order to get higher efficiency in optimization process, the objective function—cost of highway construction with detailed form was simplified in order to get the objective function with simple form, which can be used as fitness function of genetic algorithm. Optimization process was mainly divided into two stages:in the first stage, without considering the planar constraints, to use plane coordinates of fold points on the plane chain-linked line as design variables; in the second stage, taken planar constraints into consideration, to use intersection plane coordinates and circular curve radius of the initial plane design line as design variables.(4) Based on digital terrain model established in this paper and the mathematical model of horizontal alignment optimization, combination with the GAlib library technology, optimization of horizontal alignment in selection area has been realized. Comparing the relevant data of the final optimal route with the existing route, analysis result shows that the excavation and filling of the optimal route is more balanced, and if without considering facilities such as bridge and tunnel, the earthwork cost of the optimal route is more economic than the existing route.