# Stabilization Time of Running Equivalent Level \(\mathbf{L_{Aeq}}\) for Urban Road Traffic Noise
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Uncertainty \(\varepsilon\) of the Hourly \(L_{\mathit{Aeq,Ih}}\) Estimate [dB(A)]**} \\ \cline{2-7}
**Road Type** & \multicolumn{2}{c}{\(\pm\)**0.5**} & \multicolumn{2}{c}{\(\pm\)**1.0**} & \multicolumn{2}{c}{\(\pm\)**1.5**} \\ \cline{2-7}  & \(\mathbf{a}\) & \(\mathbf{b}\) & \(\mathbf{a}\) & \(\mathbf{b}\) & \(\mathbf{a}\) & \(\mathbf{b}\) \\ \hline All & 89.32 & \(-\)0.15 & 115.52 & \(-\)0.32 & 102.47 & \(-\)0.40 \\ A (motorways) & 324.46 & \(-\)0.30 & 443.14 & \(-\)0.45 & 360.25 & \(-\)0.53 \\ D (thoroughfare roads) & 97.59 & \(-\)0.13 & 195.21 & \(-\)0.32 & 277.03 & \(-\)0.45 \\ E (urban district roads) & 77.45 & \(-\)0.08 & 102.32 & \(-\)0.18 & 171.34 & \(-\)0.34 \\ F (urban local roads) & 58.14 & \(-\)0.04 & 54.87 & \(-\)0.10 & 51.58 & \(-\)0.17 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Values obtained for the constants \(a\) and \(b\) in the regression Equation (5). Figure 6: Median hourly road traffic flow \(Q_{h}\) computed for the examined dataset and the four road types. From an applicative point of view, it is important to know the cumulative probability \(P_{ST75_{\varepsilon}}\) that a preset \(ST_{75_{\varepsilon}}\) value provides a \(L_{Avg,Ih}\) estimate within a fixed uncertainty \(\varepsilon\)[14]. This probability was computed for all the road types and uncertainties \(\varepsilon\) of the \(L_{Avg,Ih}\) estimate and the results are shown in Figure 8 for some values of \(ST_{75}\). Table 5 shows that for a measurement time \(t=10\) min, the cumulative probability of \(ST_{5}\) to obtain a \(L_{Avg,Ih}\) estimate within \(\varepsilon=\pm 0.5\) dB(A) is above 50% only for motorways (type A) and remains below 50%, even doubling the uncertainty up to \(\varepsilon=\pm 1.0\) dB(A), for local roads (type F). Doubling the time \(t\) up to 20 min increases the cumulative probability but does not change the pattern observed for the accuracy interval of \(\pm 0.5\) dB(A) and road type, unless \(t\) was at least tripled or even longer. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Road Type**} & \multicolumn{3}{c}{**Uncertainty \(\varepsilon\) of the \(L_{Avg,Ih}\) Estimate [dB(A)]**} \\ \cline{2-5}  & \(\pm\)**0.5** & \(\pm\)**1.0** & \(\pm\)**1.0** & \(\pm\)**1.5** \\ \hline A (motorways) & 20 & 7 & 3 \\ D (thoroughfare roads) & 36 & 17 & 9 \\ E (urban district roads) & 41 & 25 & 12 \\ F (urban local roads) & 45 & 30 & 18 \\ \hline \hline \end{tabular} \({}^{\dagger}ST_{75}\) [min].  
\end{table} 
Table 4: Mean values in the day period 7–19 h of 75 th percentile of \(ST\) values \({}^{\dagger}\) estimated by Equation (5) for each road type and uncertainty \(\varepsilon\). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Road Type**} & \multicolumn{3}{c}{**A**} & \multicolumn{3}{c}{**D**} & \multicolumn{3}{c}{**E**} & \multicolumn{3}{c}{**F**} \\ \hline \multicolumn{2}{c}{**Mean hourly road traffic flow \(Q_{h}\) in the daytime (6–22 h) [vehicles/h]**} & \multirow{2}{*}{10,100} & \multirow{2}{*}{2140} & \multirow{2}{*}{2120} & \multirow{2}{*}{420} \\ \hline \multirow{2}{*}{**Stabilization time \(ST_{75}\) [min]**} & \multicolumn{3}{c}{**Uncertainty \(\varepsilon\) of the \(L_{Avg,Ih}\) Estimate [dB(A)]**} \\ \cline{2-2}  & \(\pm\)**0.5** & \(\pm\)**1.0** & \(\pm\)**0.5** & \(\pm\)**1.0** & \(\pm\)**0.5** & \(\pm\)**1.0** \\ \hline
10 & 51 & 79 & 28 & 62 & 16 & 56 & 8 & 38 \\
20 & 60 & 92 & 45 & 79 & 37 & 70 & 21 & 58 \\
30 & 81 & 92 & 62 & 88 & 54 & 77 & 38 & 74 \\
40 & 92 & 95 & 76 & 88 & 71 & 91 & 58 & 88 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Cumulative probability [%] of the \(L_{Avg,Ih}\) Estimate computed by Equation (5) for each road type and uncertainty \(\varepsilon\) for some \(ST_{75}\) values and daytime mean hourly road traffic flow \(Q_{h}\). Figure 7: Estimate of 75 th percentile of \(ST\) values for each type of road at each hour for uncertainty \(\varepsilon=\pm 1.0\) dB(A).