# Sustainability Analysis of the M-30 Madrid Tunnels and Madrid Rio after 14 years of Service Life
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Non-Buried M-30**} & \multicolumn{4}{c}{**Buried M-30**} & \multicolumn{4}{c}{**Convertional Materials**} & \multicolumn{4}{c}{**Buried M-30. Improved Materials**} \\ \hline \multirow{8}{*}{C14} & 131 & & 2.00 & 10 & & 1.60 & 8 & & 1.60 & 8 \\ \cline{2-11}  & 132 & & 0.00 & 0 & & 1.40 & 7 & & 1.80 & 9 \\ \cline{2-11}  & 133 & & 1.14 & 1.00 & 5 & 2.22 & 1.60 & 8 & & 2.46 & 2.00 & 10 \\ \cline{2-11}  & 134 & & 0.80 & 4 & & 1.40 & 7 & & 1.40 & 7 \\ \cline{2-11}  & 135 & & 0.00 & 0 & & 1.40 & 7 & & 1.40 & 7 \\ \cline{2-11}  & 136 & 0.07 & & 0.75 & 3 & 2.34 & & 1.75 & 7 & 2.42 & & 1.75 & 7 \\ \cline{2-11}  & 137 & 0.20 & & 0.25 & 1 & & 1.85 & & 2.50 & 10 & 1.85 & 2.50 & 10 \\ \cline{2-11}  & 138 & & 0.00 & 0 & & & 2.50 & 10 & & 2.50 & 10 \\ \cline{2-11}  & 139 & & 0.00 & 0 & & & 2.50 & 10 & & 2.50 & 10 \\ \hline \multirow{2}{*}{C16} & 127 & & 0.30 & 1 & & 2.70 & 9 & & 2.70 & 9 \\ \cline{2-11}  & 128 & & 0.09 & 0.00 & 0 & & 2.39 & & 3.50 & 10 & 2.39 & 3.50 & 10 \\ \cline{2-11}  & 140 & & 0.00 & 0 & & 1.75 & 5 & & 1.75 & 5 \\ \hline \multicolumn{11}{c}{**Sustainability index (SD)**} & \multicolumn{4}{c}{**3.43**} & \multicolumn{4}{c}{**6.26**} & \multicolumn{4}{c}{**6.74**} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 4: Value function for speed-dependent emissions and scores obtained. Similar to the aforementioned indicators, energy consumption grew during the regeneration works, with this parameter being less suitable during this period of time. However, the new facilities built were designed to reduce energy consumption (for example, in the tunnels, where energy consumption savings are 21% or 3.73 MWh/year) compared with the previous and due to the implementation of light-emitting diode (LED) technology and adjustment of the intensity of tunnel lighting according to the daylight [83], thus enhancing this indicator during the service life of the structure. Lastly, the main action performed to improve the environmental sustainability of the south-west section was the creation of Madrid Rio and recovery of the fluvial system and its ecosystem (C12, Table 2). The burial of the road and reuse of the land around the area as a green area with more than 33,000 newly planted trees and 470,000 shrubs, and 210,000 square meters of low water demand meadow, enables a reduction of 35,000 tons of CO\({}_{2}\) from the air pollution, as well as the significant reduction of noise pollution [14; 61]. However, the enhancement of these indicators has been considered medium because the original design of Madrid Rio did not contribute to restoring the natural characteristics of the Manzanares river and additional actions were performed in subsequent years [84]. It is also notable that the criterion involving the fluvial ecosystems is only dependent on the design of the structure and use of new materials does not change its value (C12, Table 2). * Social requirements: from the social point of view, the main disturbances (noise, dust and, among others, traffic congestion) produced by the M-30 renovation on the users and residents of the area should be taken into account (C13, Table 2). The works caused traffic interruptions and produced additional noise and pollutants (dust) in the area. However, the comfort of users and residents was widely increased with the construction of the tunnels and Madrid Rio. It is remarkable, for example, that the cases of people being hospitalized with health issues related to the inhalation of NO\({}_{\text{x}}\) have decreased since the renovation of the road, even when NO\({}_{\text{x}}\) still exceeds the maximum limits established by Spanish law [10]. The burial of the road and creation of the Madrid Rio park also redefined the land use of the area, enhancing leisure and cultural activities available to residents and visitors.