# Life Cycle Analysis of Road Construction and Use
## 2 Materials and Methods  
In this study, the LCIA methodology has been implemented to assess the environmental impacts of construction and use of an 8.5 km-long provincial road during 60 year-service life. The examined road offers a solution to the local and touristic traffic between two densely populated towns. Figure 1 represents the cross-section of the analyzed infrastructure: it is composed of two 1.25 m wide shoulders and two 3.50 m wide lanes. The road is in a mountainous region of central Italy, where the Appennine mountains are located. The territory morphology seriously affects the altimetric design of the infrastructure, whose 16.6% in length is raised on above- and under-grade structures. Indeed, the road is composed of:  
* 7.1 km-long open road sections (not more than 5 m-high trench or embankment cross-sections);
* 0.3 km-long 4-span new bridge with reinforced-concrete slab on three U-shaped precast reinforced-concrete beams;  
Figure 1: Design cross section (unit of measure: cm). * 1.1 km of new single-tube tunnel built with mechanized excavation. According to the geological condition, one part of the rock is granite and the other one is shale. In the joint part the overlying bedrock thickness is approximately 200 m. Water inflows were expected when tunnel excavation approached the joint of two rocks. Therefore, foam consolidation and grouting method were designed to control the displacement of the rock and its supports. Geometrical and functional issues were adopted for the road design to comply with the current Italian requirements for the construction of minor highways [30]; for the first 20 years of service life, the design traffic consists of the number of passes listed in Table 1.  
Table 2 lists the traffic spectrum of commercial and heavy vehicles within the first 20 years of service life. Given a subgrade resilient modulus equal to 90 MPa, and the traffic data in Tables 1 and 2, for a 20-year service life the flexible pavement is composed of [31]:  
* 3 cm-thick asphalt wearing course;
* 5 cm-thick asphalt binder course;
* 12 cm-thick asphalt base course;
* 30 cm-thick cement-stabilized sub-base. In order to assess the impacts of construction and use of the road for 60 years, the authors assumed that traffic volume and spectrum do not change during the overall reference service life. The bill of quantity, which is not disclosed herein, due to privacy reasons, allowed the identification of works and materials needed for the road construction. These data constituted the Life Cycle Inventory (LCI) and they were modeled according to the characterization factors listed in EN 15804:2012+A1:2013 [28] in order to calculate the Life Cycle Impact Assessment (LCIA). The characterization factors allow for comparing the ability of different substances to cause the same environmental impact because they convert the results from LCI into a common unit of a category indicator, expressed as equivalent (eq. ), (Equation (1)):  
\[IC=\sum_{x}CF_{ic}(x)\cdot INV(x) \tag{1}\]  
where \(IC\) is the Impact Category, obtained from the inventory of the substance \(x\), \(INV(x)\), and \(CF_{ic}(x)\) is the characterization factor assigned to the substance \(x\) for the calculation of \(IC\). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Vehicle Type** & **Maximum Mass (t)** & **Number of Passes** \\ \hline Commercial and heavy vehicles & 56 & 1,500,000 \\ Cars & 3 & 15,000,000 \\ Mopeds & 0.5 & 189,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Passes of vehicles within the first 20 years of service life. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Vehicle Code** & **Maximum Mass (t)** & **Number of Passes during the Service Life** \\ \hline \(V_{1}\) & 12 & 882,000 \\ \(V_{2}\) & 16 & 441,000 \\ \(V_{3}\) & 26 & 88,500 \\ \(V_{4}\) & 36 & 42,000 \\ \(V_{5}\) & 56 & 3000 \\ \(V_{6}\) & 13 & 43,500 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Traffic spectrum within the first 20 years of service life.