**8.1 STPT**

The lateral resistance was determined using STPT device in conventional and RRP235special stabilized tracks at Urmia railway station. All the characteristics are the same between tracks except ballast thickness under the sleeper.

Regarding the results, there is no significant difference between conventional and RRP235special tracks. The difference has two reasons. First, the ballast layer compaction in conventional tracks was more than RRP235special tracks, leading to higher side and end resistance. The second reason comes from the placement position of the ballast under the RRP235special track. When the roller compacts the ballast to the last stabilized layer, most ballast particles have rotated in a position that surfaces parallel to the sleeper's bottom side (**Figure 25**). So this led to the uniformity of layer decreases and

**Figure 25.** *The ballast particles placement under the sleeper in RRP235special method.*

*Developing a Novel Superstructure System for the Ballasted Railways Using RRP235special... DOI: http://dx.doi.org/10.5772/intechopen.111470*

### **Figure 26.**

*Conventional and RRP235special tracks comparison.*

caused less load transfer (**Figure 26**). Of course, this action has a beneficial side that causes increase in the contact area between ballast particles and the sleeper bottom side.
