# Influence of Stray Current on Fastening System Components in Urban Railway Tracks
## 4 Results
### Analysis of the Voltage in Fastening System Components
#### 4.1.1 Analysis of the Voltage in Anchor Bolts in the DEPP Fastening System  
In the DEPP fastening system, the diameters of the bores for the anchor bolts on the steel plate were larger than those for the bolts (Figure 8a). The contact between the steel plate and anchor bolt was made by the elastomer pad for the anchor bolts, which was proven by measuring the voltage in the anchor bolts in two cases:  
* Case 1: Elastic pads and nuts were placed on the anchor bolts (Figure 8a).
* Case 2: The elastic pads and nuts were removed from the anchor bolts (Figure 8b).  
The measured voltages are shown in Figure 9. After removing the elastic pads from the anchor bolts (case 2), the voltage in the anchor bolts was 1.7 V on bolt 1 and 1.4 V on bolt 2, indicating that the electrical connection between the anchor bolt and steel plate was established through the elastomer pad.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Type of Fastening** \\ **System** \\ \end{tabular} } & \multirow{2}{*}{**Dry Condition**} & \multicolumn{2}{c}{**Average Measured Current [A]**} \\ \cline{2-2}  & & \multicolumn{2}{c}{**Water Level on the Top of**} & \multicolumn{2}{c}{**Immersed Condition**} \\ \hline ZG 3/2 & 0.09 & 0.14 & 0.54 \\ \hline PPE & 0.08 & 0.12 & 0.52 \\ \hline DEPP & 0.04 & 0.05 & 0.63 \\ \hline Zagreb 21-CTT & 0.02 & 0.04 & 0.76 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Measured current value for each testing case.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Component of** \\ **Fastening** \\ **System** \\ \end{tabular} } & \multicolumn{6}{c}{**Direct Fastening Systems**} & \multicolumn{6}{c}{**Indirect Fastening Systems**} \\ \cline{2-11}  & \multicolumn{3}{c}{**ZG 3/2**} & \multicolumn{3}{c}{**PPE**} & \multicolumn{3}{c}{**DEPP**} & \multicolumn{3}{c}{**Zagreb 21-CTT**} \\ \cline{2-11}  & \multicolumn{3}{c}{**Case Number**} & \multicolumn{3}{c}{**Case Number**} & \multicolumn{3}{c}{**Case Number**} & \multicolumn{3}{c}{**Case Number**} \\ \cline{2-11}  & **I** & **II** & **III** & **I** & **II** & **III** & **I** & **III** & **I** & **II** & **III** \\ \hline Rail & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 \\ \hline Clip 1 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 \\ \hline Clip 2 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 \\ \hline T-bolt 1 & - & - & - & - & - & - & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 & 26.05 \\ \hline T-bolt 2 & - & - & - & - &In addition, notably, a large difference was observed between the voltages measured in Case 1 for anchor bolts 1 and 2 (Figure 9), even though the anchor bolts were connected to the steel plates with the same type of nuts and elastic pads. The electrical resistance of the elastic pads was measured to determine whether the different resistance values were responsible for the different voltages in the anchor bolts. The resistance of the elastic pad for anchor bolt 1 was 2.29 k\(\Omega\), and the resistance of the pad for anchor bolt 2 was 1980.28 k\(\Omega\), which confirmed the original assumption that the differing values of the electrical resistance of the elastic pads caused the difference in the measured voltages in the anchor bolts.