*5.3.4 Afol from ISO 9613-2 approach*

For this case study, *df* = 61 m. Thus, according to ISO 9613-2, the attenuation values to be considered are presented in **Table 17**.

The IL due to the propagation through a green barrier or dense foliage according to ISO 9613-2 and the SPL expected at the receiver are presented in **Table 18**. No values were needed to be replaced.

### **5.4 Edge diffraction**

When an acoustic barrier is calculated as a "conventional" one (e.g., by using Kurze-Anderson's approach or thick barrier approach), not only the top edge diffraction is to be considered, but also the diffraction at its sides. The SPL due to the diffraction at its sides should be added to the expected sound pressure levels at the receiver.

**Figure 11** shows a diagram of the sides that should be considered to obtain the diffracted SPL at the receiver. Since lateral paths are not symmetric, each of them will be calculated separately.


#### **Table 17.**

*Green barrier attenuation, in dB/m (from [5]).*


#### **Table 18.**

*IL according to ISO 9613-2 and expected sound pressure levels at P1 (all values are in dB).*

**Figure 11.** *Diffraction lateral paths to be considered.*

**Figure 12.** *Diagram of dimensions for calculation of North side diffraction.*
