## 4 Results and Discussion
### Carbon Emissions of the Case Bridge  
The case bridge component information and carbon emissions are summarized in Table 2. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Component**} & \multirow{2}{*}{**Number**} & \multirow{2}{*}{**Project**} & \multicolumn{6}{c}{**Carbon Emissions (kgCO\({}_{2}\))**} \\ \cline{4-7}  & & & **Material** & **Transportation** & **Mechanical** & **Single Summary** & **Total Carbon Emissions** \\ \hline \multirow{4}{*}{Bored pile (C25)} & & Drilling & \(1.91\times 10^{2}\) & 0.00 & \(4.83\times 10^{2}\) & \(6.74\times 10^{2}\) & \(4.92\times 10^{4}\) \\  & & Cast-in-place concrete & \(1.31\times 10^{4}\) & \(5.72\times 10^{2}\) & \(2.20\times 10^{2}\) & \(1.39\times 10^{4}\) & \(1.01\times 10^{2}\) \\  & & Steel bars & \(2.66\times 10^{4}\) & \(8.98\times 10^{2}\) & \(5.77\times 10^{2}\) & \(2.81\times 10^{4}\) & \(2.05\times 10^{2}\) \\  & & Concrete & \(6.54\times 10^{4}\) & \(2.54\times 10^{2}\) & \(1.10\times 10^{2}\) & \(6.90\times 10^{2}\) & \(3.31\times 10^{2}\) \\  & & Steel bars & \(1.19\times 10^{4}\) & \(3.99\times 10^{2}\) & \(2.74\times 10^{2}\) & \(1.25\times 10^{4}\) & \(6.01\times 10^{2}\) \\ \multirow{4}{*}{Abutment-cast-in-place (C35)} & & Concrete & \(9.25\times 10^{3}\) & \(3.66\times 10^{2}\) & \(1.58\times 10^{2}\) & \(9.77\times 10^{3}\) & \(5.86\times 10^{4}\) \\  & & Steel bars & \(1.71\times 10^{4}\) & \(5.75\times 10^{2}\) & \(3.94\times 10^{2}\) & \(1.80\times 10^{4}\) & \(1.08\times 10^{4}\) \\  & & Concrete & \(6.11\times 10^{4}\) & \(2.49\times 10^{3}\) & \(7.01\times 10^{2}\) & \(6.43\times 10^{4}\) & \(7.71\times 10^{4}\) \\  & & Steel bars & \(5.80\times 10^{4}\) & \(1.95\times 10^{4}\) & \(9.84\times 10^{2}\) & \(6.10\times 10^{4}\) & \(7.32\times 10^{4}\) \\  & & Concrete & \(5.13\times 10^{3}\) & \(2.07\times 10^{2}\) & \(2.50\times 10^{2}\) & \(5.36\times 10^{3}\) & \(6.43\times 10^{4}\) \\  & & Steel bars & \(4.84\times 10^{3}\) & \(1.63\times 10^{2}\) & \(1.20\times 10^{2}\) & \(5.10\times 10^{3}\) & \(6.12\times 10^{4}\) \\ Prestressed reinforced concrete & & Concrete & \(2.89\times 10^{3}\) & \(1.07\times 10^{2}\) & \(9.09\times 10^{3}\) & \(3.09\times 10^{3}\) & \(4.01\times 10^{3}\) \\  & & Steel bars & \(1.20\times 10^{4}\) & \(4.03\times 10^{2}\) & \(3.94\times 10^{2}\) & \(1.28\times 10^{4}\) & \(1.66\times 10^{4}\) \\  & & Install & \(1.65\times 10^{2}\) & \(5.98\times 10^{2}\) & \(3.66\times 10^{2}\) & \(1.10\times 10^{3}\) & \(1.43\times 10^{4}\) \\ Concrete bridge deck and asphalt & & Surface layer & \(1.21\) & 8.10 & 0.69 & 9.99 & \(4.18\times 10^{4}\) \\ concrete bridge deck (C30) & & Low level & \(1.13\times 10^{3}\) & 8.10 & 0.09 & \(1.95\times 10^{3}\) & \(8.16\times 10^{4}\) \\  & & Install (C30) & 632 & Brick & \(3.21\times 10^{3}\) & \(2.09\times 10^{3}\) & \(0.00\) & \(5.29\times 10^{3}\) & \(3.35\times 10^{4}\) \\  & & Concrete & \(1.34\times 10^{3}\) & 6.48 & 1.59 & \(1.35\times 10^{3}\) & \(3.11\times 10^{3}\) \\  & & Steel bars & \(7.53\times 10^{3}\) & 2.54 & 0.17 & \(7.80\times 10^{3}\) & \(1.79\times 10^{4}\) \\  & & 460 & Cast iron Columns and railings & \(2.35\times 10^{2}\) & 7.49 & 0.00 & \(2.43\times 10^{2}\) & \(1.12\times 10^{3}\) \\ \hline \hline \end{tabular} (1) Comparison of bridge carbon emissions in different stages  
\end{table} 
Table 2: Summary of component information and carbon emissions. Figure 3: Diagram of the case bridge. The carbon emissions of the case bridge at different stages are shown in Figure 4. The figure shows that the carbon emissions in the material production stage are the largest as they reach 7.96 \(\times\) 10\({}^{6}\) kg, the carbon emissions in the construction stage are only 2.08 \(\times\) 10\({}^{5}\) kg, and the carbon emissions generated by material transportation are 4.72 \(\times\) 10\({}^{5}\) kg, which are probably 2.3 times greater than the carbon emissions in the construction stage.