Surveying Network Design and Adjustment for Ballastless Track HSR: Case Study with the First HSR in China

摘要

The ballastless track can overcome the disadvantages of a traditional ballast track, such as lower longitudinal and lateral permanent stability and expensive maintenance, and is thus suitable for a high-speed railway (HSR) that is 350 km/h or even faster. The continuous track slabs in the ballastless track have very precise geometric parameters and must be precisely installed to guarantee the ride comfort of a high-speed train. Therefore, the so-called CPIII control network was built, for which both careful field surveying and rigorous data adjustment were performed. In this paper, how the CPIII network is built in a hierarchical procedure will be systematically introduced. More importantly, a new data-processing strategy is proposed, including free and constrained network adjustment realized by using different S-datum matrices. In free network adjustment, data snooping and variance component estimation (VCE) are interactively implemented for excluding outliers and retrieving realistic observation precisions. In constrained network adjustment, quasi-stable adjustment along with hypothesis testing is implemented to select the stable control points, followed by tightly constrained adjustment to obtain the coordinates of CPIII points. With the first ballastless track HSR in China as an example, the performance of proposed data-processing strategies is demonstrated, showing the importance and efficiency of data snooping, VCE, and selection of stable points. Following the strategy of network design, field data collection, and data processing, the ultraprecision results with reasonable quality control can be achieved to meet HSR demand.