# Cost Overrun Causative Factors in Road Infrastructure Projects: A Frequency and Importance Analysis
## 3 Results and Discussion
### Network Analysis  
The authors built the graph of connections between the cost overrun factors, according to the methodology of network analysis (Figure 3). Each cost overrun factor was represented with a node \begin{table}
\begin{tabular}{c c c c c} \hline
**Id** & **Category** & **Relative Frequency** & _AII_ & **Category Rank** \\ \hline C\({}_{1}\) & Design & 17.22\% & 4.37\% & 1 \\ C\({}_{8}\) & Programming and control & 5.56\% & 1.90\% & 2 \\ C\({}_{2}\) & Financial & 13.89\% & 1.07\% & 3 \\ C\({}_{3}\) & Project & 10.56\% & 0.74\% & 4 \\ C\({}_{7}\) & Contract & 6.11\% & 0.46\% & 5 \\ C\({}_{11}\) & Laws and regulations & 3.89\% & 0.32\% & 6 \\ C\({}_{6}\) & External factors & 8.89\% & 0.25\% & 7 \\ C\({}_{4}\) & Contractor & 8.89\% & 0.25\% & 8 \\ C\({}_{9}\) & Site & 5.00\% & 0.24\% & 9 \\ C\({}_{5}\) & Owner & 8.89\% & 0.20\% & 10 \\ C\({}_{12}\) & Personal & 3.89\% & 0.19\% & 11 \\ C\({}_{10}\) & Contractal relationships & 4.44\% & 0.14\% & 12 \\ C\({}_{13}\) & Materials & 1.67\% & 0.13\% & 13 \\ C\({}_{15}\) & Equipment & 0.56\% & 0.02\% & 14 \\ C\({}_{14}\) & Consultant & 0.56\% & 0.02\% & 15 \\ \hline \end{tabular}
\end{table} 
Table 8: Top cost overrun categories according to the Average Influence Index (_All_). \begin{table}
\begin{tabular}{c c c} \hline
**Stakeholder’s Group** & _SII_ & **Ranking** \\ \hline Designer and Consultant & 40.51\% & 1 \\ Owner & 28.45\% & 2 \\ External Agent & 23.32\% & 3 \\ Contractor & 7.07\% & 4 \\ Supplier and Subcontractor & 0.66\% & 5 \\ \hline \end{tabular}
\end{table} 
Table 9: Stakeholder Influence Index (SII). and each connection with an edge. The diameter of the nodes represents the degree of each factor, i.e., the nodes with the largest diameter represent the cost overrun factors with the highest degree. The width of the edge represents the number of papers that mention the pair of nodes in their top-ten of cost overrun factors of road projects, that is, a wider edge implies that there is a greater number of papers that present that pair of factors. Figure 3 represents the network of cost overrun factors for road projects. To build this network, the authors used the free software Gephi 0.9.2 and the Force Atlas rendering algorithm, which groups the nodes with the strongest relative interaction through attraction and repulsion forces. The top-ten cost overrun factors with the highest degree are: 'failures in design', 'inadequate project planning', 'unrealistic contract duration', 'price variation of materials', 'legal issues', 'design changes', 'project scope changes', 'inadequate bidding method', 'financial difficulties of owners', and'staffing problems'. In addition, the green color of the nodes in Figure 3 represents the betweenness centrality of each node, i.e., the nodes with a darker green are the factors with the highest betweenness centrality. Therefore, the top-ten cost overrun factors with the highest centrality are: 'failures in design', 'unrealistic contract duration', 'inadequate project planning', 'legal issues', 'project scope changes', 'price variation of materials', 'design changes','staffing problem', 'late decision making by owner', and 'financial difficulties of owner'. A comparison of the degree measures, centrality and the influence index obtained in Section 3.4.1 confirms the following cost overrun factors of road projects as the most influential: 'failures in design', 'price variation of materials', 'inadequate project planning', 'project scope changes', 'design changes', and 'unrealistic contract duration'. Therefore, the need for management in the early stages of the project, i.e., during planning and design, is reinforced. 'failures in design' and 'design changes' could be solved through the implementation of BIM and Lean construction approaches. 'Price variation of materials', 'inadequate project planning', 'project scope changes', and 'unrealistic contract duration' could be addressed through transparent collaboration and information practices; both are basic principles of  
Figure 3: Representations of cost overrun factors’ network.