## 5 Guardrail Interval Limits for Main Turnout Types and Analysis of Influencing Factors  
Considering the influence of the vehicle running attitude, different turnouts require different guardrail interval limits. However, to facilitate field maintenance, a unified limit needs to be set that is applicable to all types of turnouts. To establish a reasonable guardrail interval limit that meets the needs of most types of turnouts and reduces the wheel-track impact and abrasion in the opening section, the proposed calculation method was used to determine the limits for single turnouts and double-slip turnouts widely used by major railways in China. The calculation results are presented in Tables 1 and 2. The calculated guardrail interval limits were distributed between 1365 and 1367 mm. For single turnouts, the No. 9 single turnout for 50 kg/m rail (Design Drawing No. CZ2209) required the smallest guardrail interval limit of 1365.48 mm, and the No. 18 single turnout for 50 kg/m rail (Design Drawing No. ZX 4275) required the largest guardrail interval limit of 1366.98 mm. For double-slip turnouts, the No. 9 double-slip turnout for 50 kg/m rail (Design Drawing No. CZ2214) required the smallest guardrail interval limit of 1365.52 mm, and the No. 12 double-slip turnout for 60 kg/m rail (Design Drawing No. SC350) required the largest guardrail interval limit of 1366.64 mm. For actual maintenance and repair, the guardrail interval limit should be 1365 mm, which will meet the needs of most turnouts and effectively avoid the occurrence of wheel-track impact in the opening section of guardrail and prevent derailment accidents. The calculation results showed a strong correlation between the guardrail interval limit and turnout alignment parameters. Figures 12 and 13 show the influence of different alignment parameters on the guardrail interval limits of single turnouts and double-slip turnouts, respectively. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline
**Turnout Type** & **Design Drawing Number** & **Radius of the Lead Curve** & **Distance from the End of the Edge** & **Distance from the End of the End Curve to the End of the Buffer the Buffer the End of the Buffer of the Guardrail & **Gage of the Buffer of the Guardrail** & **Distance from the End of the Buffer of the Guardrail & **Distance from the End of the Buffer of the Guardrail & **Gage at the End of the Buffer** & **Gage at the End of the Guardrail \\
**50-6 Symmetric turnout** & **SC384** & **180 m** & **15 mm** & \(-\)**135.03 mm** & \(-\)**133.95 mm** & **1435.67 mm** & **1365.75 mm** \\
60-6 Symmetric turnout & **SC382** & **180 m** & **15 mm** & \(-\)**185.41 mm** & \(-\)**183.9 mm** & **1440.04 mm** & **1365.77 mm** \\
50-9 single turnout & **CZ2209** & **180 m** & **15 mm** & **205.06 mm** & **205.03 mm** & **1435 mm** & **1365.48 mm** \\
60-9 single turnout & **CZ577** & **360 + 190 m** & **15 mm** & **251.49 mm** & **251.5 mm** & **1435 mm** & **1366.23 mm** \\
50-12 single turnout & **ZX4257** & **350 m** & **0 mm** & **161.83 mm** & **/** & **1435 mm** & **1366.81 mm** \\
60-12 single turnout & **SC330** & **350 m** & **0 mm** & **113 mm** & **/** & **1435 mm** & **1366.80 mm** \\
60-12 single turnout & **ZX4249** & **350 m** & **0 mm** & **314.74 mm** & **/** & **1435 mm** & **1366.86 mm** \\
60-18 single turnout & **ZX4275** & **1120 m** & **0 mm** & \(-\)**9836.72 mm** & **/** & **1435 mm** & **1366.98 mm** \\
60-18 single turnout & **YX1302** & **1000 m** & **0 mm** & \(-\)**6729.89 mm** & **/** & **1435 mm** & **1366.97 mm** \\ \hline  & & & & & & & \\ \end{tabular} Note: with respect to the distance from the end of the lead curve or the end of gage widening to the end of the buffer segment of the guardrail, a positive value suggests that the endpoint is outside of the end of the buffer segment of the guardrail, and a negative value suggests that the endpoint has entered the end of the buffer segment of the guardrail.  
\end{table}