ATS(Automatic Train Stop)s are is effected by track environment, signal distance and train braking distance. So onboard signaling systems such as ATP(Automatic Train Protection) are installed on conventional lines by some train operation companies. With the mixed signalling, the onboard signaling system is overlaid on a conventional line with ATS, it is possible to run the line with conventional trains and ATP trains and to use the advantages of ATP(higher speed or more trains on the line). This paper includes guidelines a mixed signalling(ETCS and ATS) system architecture, operation concepts and infill balise installation.