In order to reach a desired quality in railway tracks and to maintain this quality in an acceptable level, a systematic and regular maintenance plan must be performed. By proper management of track maintenance and codification of proper methods to evaluate the quality of railway tracks, a desired quality can be reached. For this purpose, some indices should be defined and maintenance limits of railway tracks should be determined based on these indices. Various geometrical indices have been defined in the railways and these indices are utilized by maintenance management systems. Each of these indices, because of their limitations or some special conditions, is not dependable in some tracks and their results are not acceptable. So, the main aim of this research is to develop a dependable geometrical index and the PSD
[1] method is used to achieve this goal. This paper has been tried to utilize a recently developed index compared with other indices and the relationship between this index and other indices is expressed. That is, by developing the PSD index, the relationship between PSD and TGI, PSD and CTR geometrical indices has been expressed. It was found that either of mentioned indices (TGI and CTR) has a linear relationship with PSD index. By comparing the indices it is concluded that PSD index provides more details about the geometrical status of the track. Thus, using PSD index, track maintenance decision makers will be able to schedule the maintenance programs effectively.