**Abstract**

The ballasted tracks have been considered due to their benefits such as low construction cost, simple technology, good performance in vibration, and proper drainage. Despite the advantages, low bearing capacity, time-consuming maintenance, low vertical stiffness, vertical and horizontal displacement, and ballast problems are the reasons for the scientist's effort to enhance the track using different methods. The problems increase in the presence of clay. The Royal Road Product 235 Special (RRP235Special) have used in road construction since 1960s. In this regard, all the layers underneath the sleeper have been replaced with the clayey subgrade stabilized with RRP235Special. A series of static and dynamic lab tests with different additive dosages were carried out to investigate the stabilized soil properties, and an optimal percentage was found. The sample with 0.15 lit/m<sup>3</sup> RRP235Special was determined as the suitable dosage for lab experiments. According to the lab experiment results, a track was constructed in Urmia railway station, and field tests such as single tie push test (STPT) and plate loading test (PLT) were carried out. The conventional system is compared to the proposed superstructure. As a result, STPT has no significant difference, and PLT was increased due to the use of RRP235special.

**Keywords:** RRP235Special, soil stabilization, ballast box test, track damping, track stiffness, track settlement, STPT, PLT
