# A Novel Methodology for Planning Urban Road Safety Interventions
## 4 Validation of the Proposed Methodology via Case Study Application
### Intervention Prioritization  
Intervention priorities were determined through a cost-benefit ratio (B/C) analysis of the proposed solutions. By evaluating the social cost reduction benefits of reducing \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**[c/Year]**} & \multicolumn{2}{c}{**SC\({}_{\text{F}}\)**} & \multicolumn{2}{c}{**SC\({}_{\text{SI}}\)**} & \multicolumn{2}{c}{**SC\({}_{\text{TOT}}\)**} & \multicolumn{2}{c}{**SC\({}_{\text{saved}}\)**} \\ \cline{2-9}  & **East** & **West** & **East** & **West** & **East** & **West** & **East** & **West** \\ \hline Opt.0 & 157,147.48 & 383,106.33 & 222,709.97 & 542,939.66 & 379,857.45 & 926,045.99 & - & - \\ Opt.1 & 118,373.80 & 275,966.24 & 167,759.77 & 391,100.34 & 286,133.57 & 667,066.58 & 93,723.88 & 258,979.40 \\ Opt.2 & 136,840.04 & 327,448.32 & 193,930.19 & 464,060.93 & 330,770.22 & 791,509.25 & 49,087.22 & 134,536.74 \\ \hline \hline \end{tabular} Preliminary cost estimates were conducted for two proposed traffic-calming solutions at critical points B1, and B2. Option 1 includes central pedestrian refuge islands, while Option 2 involves Berlin cushions to reduce vehicle speed (see Table 7). Both interventions aim to enhance pedestrian and cyclist safety.  
\end{table} 
Table 6: SC saved for the east and west directions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Intervention Option (1)** & **Unitary Cost [c]** & **Unit** & **Quantity** & **Cost [c]** \\ \hline \multicolumn{5}{c}{**Hook-shaped refuge island**} \\ \multicolumn{5}{c}{Paving} & 23.80 & m\({}^{2}\) & 8 & 190.40 \\ Island curbs & 18.92 & m & 16 & 302.72 \\ Vertical obstacle warning sign & 39.55 & each & 2 & 79.10 \\ Horizontal zebra stripes & 6.93 & m\({}^{2}\) & 4 & 27.72 \\ Pedestrian path delimitation Curbs & 18.92 & m & 12 & 227.04 \\ Pedestrian crossing & 6.93 & m\({}^{2}\) & 10 & 69.30 \\ Sub-total & & & & 896.28 \\
**Bus stops, with central island** & & & & \\ \multicolumn{5}{c}{Paving} & 23.80 & m\({}^{2}\) & 60 & 1428.00 \\ Island curbs & 18.92 & m & 120 & 2270.40 \\ Vertical obstacle warning sign & 39.55 & each & 4 & 158.20 \\ Horizontal zebra stripes & 6.93 & m\({}^{2}\) & 10 & 69.30 \\ Pedestrian crossing & 6.93 & m\({}^{2}\) & 16 & 110.88 \\ Sub-total & & & & 4036.78 \\ Total & & & & 4933.06 \\ Real cost, VAT included (\(\times\)1.35) & & & & 6659.63 \\ \hline \multicolumn{5}{c}{**Intervention option (2)**} & **Unitary Cost [c]** & **Unit** & **Quantity** & **Cost [c]** \\ \hline Recycled rubber prefabricated unit & 500.00 & each & 4 & 2000.00 \\ Installation & 200.00 & each & 4 & 800.00 \\ Total & & & & & 2800.00 \\ Real cost, VAT included (\(\times\)1.35) & & & & 3780.00 \\ \hline \hline \end{tabular}
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Table 7: Cost estimation of proposed interventions. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**[n\({}^{\circ}\)/Year]**} & \multicolumn{2}{c}{**Fatalities**} & \multicolumn{2}{c}{**Serious Injuries**} & \multicolumn{2}{c}{**FSI**} & \multicolumn{2}{c}{**FSI\({}_{\text{saved}}\)**} \\ \cline{2-9}  & **East** & **West** & **East** & **West** & **East** & **West** & **East** & **West** \\ \hline Opt.0 & 0.086 & 0.211 & 0.476 & 1.162 & 0.563 & 1.373 & - & - \\ Opt.1 & 0.065 & 0.152 & 0.359 & 0.837 & 0.424 & 0.989 & 0.139 & 0.384 \\ Opt.2 & 0.075 & 0.180 & 0.415 & 0.993 & 0.490 & 1.173 & 0.072 & 0.199 \\ \hline \hline \end{tabular}
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Table 5: FSI saved for the east and west directions. accidents alongside the costs of implementation, the B/C ratio provided a robust criterion for selecting the most effective interventions. The B/C ratio allows for the comparison of various proposals to identify those that maximize benefits relative to costs, focusing resources on measures that have the greatest impact on reducing accident-related social costs. The decision-making process consists of two phases. In phase 1, for each critical site, the intervention proposal with the highest B/C ratio is selected as the most efficient solution (see Table 8).