In order to reduce the cost of track maintenance, grouted ballastless tracks for existing lines where ballast voids are filled with cement grout have been developed and put into practical use. However, there is a problem that some constructed grouted ballastless tracks laid on soft roadbeds are in need of repair within only a few years after operations restart. Therefore, we have developed a method for improving grouted ballastless tracks laid on soft roadbeds and carried out construction work to verify the developed method on existing lines. The roadbed improvement thickness for construction was determined according to design flow proposed in this paper. This paper also describes the improvement method developed for grouted ballastless tracks for existing lines and its verification results.
