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

AbstractThe 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...