Do public-private partnerships perform better? A comparative analysis of costs for additional work and reasons for contract changes in Dutch transport infrastructure projects

An important reason to procure transport infrastructure projects through Public-Private Partnerships (PPPs) is that they are expected to have a better cost performance compared to regular infrastructure procurement. However, the evidence for this is weak. Therefore, this article analyzes the cost performance (in terms of costs for additional work caused by contract changes during project implementation) of Design-Build-Finance-Maintain (DBFM) projects versus Design and Construct (D&C) projects. DBFM is considered a type of PPP and D&C is not. Data were collected on 58 projects from the Project Database of Rijkswaterstaat and analyzed using nonparametric tests. The results show that DBFM-projects have a significantly better cost performance than D&Cprojects, especially concerning costs for additional work due to technical necessities. Because scope adjustments are the main reason for contract changes across the D&C- and DBFM-projects, cost performance can be improved particularly by curbing scope adjustments costs.