## 5 Methods
### Calibration Factor  
Calibration was carried out to transfer the predictive model developed in the USA to the Italian context. The calibration factor (\(C_{X}\)) is computed as expressed in Equation (7). \[C_{X}=\frac{\sum\limits_{all}\ N_{observed}}{\sum\limits_{all}\ N_{predicted\ n.c.}} \tag{7}\] \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Facility Type**} & \multirow{2}{*}{**CMF**} & \multirow{2}{*}{**CMF Description**} & \multicolumn{4}{c}{**Average CMF Value**} \\ \cline{5-6}  & & & & \multicolumn{2}{c}{**Redesigned Road**} \\ \cline{5-6}  & & & & **Rehabilitated Road** & **Bypasses** \\ \hline \multirow{4}{*}{**Segments a**} & \(\text{CMF}_{1r}\) & Lane width & 1.01 & 1.01 & 1.01 \\  & \(\text{CMF}_{2r}\) & Shoulder width and type & 1.22 & 1.09 & 1.09 \\  & \(\text{CMF}_{3r}\) & Horizontal curvature & 3.49 & 2.06 & 1.23 \\  & \(\text{CMF}_{5r}\) & Grade level & 1.03 & 1.04 & 1.01 \\  & \(\text{CMF}_{6r}\) & Driveway density (DD) & 1.39 & 1.34 & 1 \\  & \(\text{CMF}_{10r}\) & Roadside Hazard Rating (RHR) & 1.14 & 1.07 & 1.07 \\ \hline \multirow{4}{*}{**Intersections (3 ST) b**} & \(\text{CMF}_{1i}\) & Intersection Skew Angle & 1.09 & 1.07 & - \\  & \(\text{CMF}_{2i}\) & Intersection Left-Turn Lanes & 0.90 & 0.94 & - \\ \cline{1-1}  & \(\text{CMF}_{3i}\) & Intersection Right-Turn Lanes & 0.97 & 0.94 & - \\ \cline{1-1}  & \(\text{CMF}_{4i}\) & Lighting & 0.93 & 0.94 & - \\ \hline \hline \end{tabular}  
* a 278 segments for existing road, and 157 segments for the redesigned road (120 on rehabilitated road and 37 on bypasses). b 32 intersections for existing road, and 7 intersections for the redesigned road (7 on rehabilitated road and 0 on bypasses).  
\end{table} 
Table 6: Comparison of average CMFs values for different scenarios. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Facility Type**} & \multirow{2}{*}{**CMF**} & \multirow{2}{*}{**CMF Description**} & \multicolumn{2}{c}{**Data Need for**} & \multirow{2}{*}{**Data Availability**} \\  & & & & **Calibration** & **for This Study** \\ \hline \multirow{8}{*}{**Segments**} & \(\text{CMF}_{1r}\) & Lane width & 12 feet & Required & Yes \\  & \(\text{CMF}_{2r}\) & Shoulder width & 6 feet & Required & Yes \\  & \(\text{CMF}_{2r}\) & Shoulder type & Paved & Required & Yes \\  & \(\text{CMF}_{5r}\) & Horizontal curvature & None (\(R=\infty\)) & Required & Yes \\  & \(\text{CMF}_{4r}\) & Vertical curvature & None & Desirable & No \\  & \(\text{CMF}_{5r}\) & Grade level & 0\% & Desirable & Yes \\  & \(\text{CMF}_{6r}\) & Driveway density (DD) & 5 driveways per mile & Desirable & Yes \\  & \(\text{CMF}_{7r}\) & Centering rumble strips & None & Desirable & No \\  & \(\text{CMF}_{8r}\) & Passing lanes & None & Desirable & No \\  & \(\text{CMF}_{9r}\) & Two-way left-turn lanes & None & Desirable & No \\  & \(\text{CMF}_{10r}\) & Roadside Hazard Rating (RHR) & 3 & Desirable & Yes \\  & \(\text{CMF}_{11r}\) & Lighting & None & Desirable & No \\  & \(\text{CMF}_{12r}\) & Automated speed enforcement & None & Desirable & No \\ \hline \multirow{4}{*}{**Intersections (3 ST, 4 ST, 45G)**} & \(\text{CMF}_{1i}\) & Intersection Skew Angle & 0\({}^{\circ}\) & Desirable & Yes \\  & \(\text{CMF}_{2i}\) & Intersection Left-Turn Lanes & None & Required & Yes \\ \cline{1-1}  & \(\text{CMF}_{3i}\) & Intersection Right-Turn Lanes & None & Required & Yes \\ \cline{1-1}  & \(\text{CMF}_{4i}\) & Lighting & None & Required & Yes \\ \hline \hline \end{tabular}  
* a 278 segments for existing road, and 157 segments for the redesigned road (120 on rehabilitated road and 37 on bypasses). b 32 intersections for existing road, and 7 intersections for the redesigned road (7 on rehabilitated road and 0 on bypasses).  
\end{table} 
Table 5: CMFs for roadway segments and intersections of rural two-way two-lane roads with corresponding ‘base’ conditions and data availability for this study [9].