Further development of the roadway network in Ukraine will basically take place by modernization, which, in fact, conversion of the system « Road Conditions-Traffic Flow-Environment» from one state to another. Generally, it changes not only the spatial axle position of an existing road, but also the geometric and technological parameters of the road. Modern technological design and construction processes demand higher accuracy and reliability in determining the output spatial parameters measured with survey methods and techniques. Therefore, substantiated higher accuracies and improved survey techniques are tasks of primary importance. They must be solved on the basis of determination of rational error limits in survey works and their influence on the accuracy of building, transport operational and economical parameters of the project and actual engineering structures. The objective of the study is to demonstrate possibilities and efficiency in using various models of the system of ensuring the accuracy in survey works for roadway modernization and for solving other tasks on determination of geometric element parameters of complicated sections on existing roadways.