Smart maintenance is essential to achievinge a safe and reliable railway, but traditional 11 maintenance deployment is costly and heavily human-involved. InA low-effective job execution or 12 failure in preventive maintenance can lead to railway service disruption and unsafe operations. The 13 deployment of robotic and autonomous systems was proposed to conduct these maintenance tasks 14 with higher accuracy and reliability. In order for tThese systems to be, for being capable of detecting rail flaws along 15 millions of mileages they must, necessitate to register their location with higher accuracy. A prerequisite of an 16 autonomous vehicle is its possessing a high degree of accuracy in terms of its positional awarenessown positional awareness with the highest degree of accuracy. This paper 17 first reviews the importance and demands of preventive maintenance in railway network and the 18 related techniques. Further, the investigation about the strategies, techniques, architecture, and ref-19 erences used by different systems to resolve the location along the railway network is conducted. 20 Then, the on-board based and infrastructure-based sensing are discussed for the advantages and 21 applicability, respectively. Finally, the uncertainties which contribute to vehicle’s position error and 22 influence on positioning accuracy and reliability, are analysed with corresponding technique solu-23 tions. This study therefore provides an overall direction for further autonomous track-based system 24 design and methods developing to deal with the challenges faced in the railway network.