Application Of Google Earth’s Data In Feasibility Study Stage Of Road Engineering

Since the reform and opening up,China’s transportation has been vigorously supported and developed rapidly.In 2016,the transportation infrastructure investment exceeded 2trillion and 600 billion.At present,our country’s road network has basically formed,but there still exist some problems,such as insufficiency of total and structural contradiction.In2030,there are 26 thousand kilometers’ national highway to build,and 100 thousand kilometers’ national and provincial trunk highways to reform and upgrade.It can be seen that the road engineering projects are huge in quantity and require more investment.In order to make scientific decision for engineering project construction,the feasibility study is an important part of road engineering.Outdoor surveying is an important step for working out the feasibility study report of project,in this stage,topographic maps of which scale are1:10000 are generally used and usually mapped with aerial photography technology.Too much outdoor surveying will lead to waste of resources,but too little will not meet the requirements.Aerial photogrammetry is usually used for surveying and mapping,but its disadvantages are high cost(800-1000 yuan /2km)and easy to affect by the weather.If entirely using GPS technique to measure,it can be difficult to work in complex terrain,and cost of manpower is great.There is a huge amount of money,and more investment is needed.In order to make mapping simpler and more economic,research on using data of Google Earth to help surveying and mapping has important practical significance.And on this basis,using AutoCADCivil3 D to help 3D visualization design.In this paper,based on the digital topographic map of a region in China from field surveying,use modified ground elevation data of Google Earth combined with AutoCADCivil3 D to make digital topographic map and design 3D road,which are mainly used in the feasibility study stage of road survey and design.In order to ensure the height accuracy of Google Earth can meet the requirements of actual project,and can be practically used in road design.This article takes the ground elevation data of Google Earth,method of improving height accuracy of Google Earth and application of Google Earth data in road survey engineering as the main study object,the main research contents are as follows:(1)Study the source and elevation system of Google Earth data,make a comparisonbetween the elevation data of actual engineering digital topographic map and the elevation data of Google Earth to determine the error between the Google Earth elevation and the actual engineering elevation.(2)Analogy with the elevation anomaly fitting,study the good and bad points of quadratic polynomial surface fitting,cubic polynomial surface fitting and Matlab V4 interpolation and neural network in establishing elevation error model between the data of Google Earth and the measured data.(3)Study whether the modified ground elevation data of Google Earth can be used in the the feasibility study stage of road engineering and whether the modified data will be limited.(4)Study the steps and advantage 3D terrain modeling and 3D road design,through the combination of Google Earth and Auto CAD Civil 3D,the practicability of Google Earth is brought into platy and the simple method for road engineering design are provided.The research conclusion: the source of Google Earth elevation data is STRM-3 data,which has an error higher than the allowable error of 1:10000 topographic maps between the normal elevation used in our country’s project;To build a fitting or interpolation model of ground elevation error,the flexible use of cubic polynomial surface fitting model and neural network method for fitting is a reasonable choice,which can effectively forecast the elevation error everywhere in the model,greatly improve the precision of Google Earth elevation;Take Google Earth data somewhere in China as an example,after improving the accuracy,the Google Earth data of flat terrain area can still not meet the requirements of1:10000 topographic map,but the Google Earth data of hilly terrain area can meet the requirements;Google Earth and Auto CAD Civil 3D can be simply and effectively combined to provide a more convenient,vivid and specific design process and method for road survey,design and display in the feasibility study.In summary,this study can make the survey and design of feasibility study stage of road engineering more convenient and more economical,significantly improve the accuracy of Google Earth ground elevation data for actual engineering,and provide a reference for the development trend of road survey and design.