Developing a Preliminary Engineering Cost Estimation Method for a Portfolio of Bridge Construction Projects in Project Planning Phase

For state departments of transportation (DOTs), estimating preliminary engineering (PE) costs over a multiple-year horizon is critical for proper planning of engineering resources and budgets to ensure timely delivery of a portfolio of bridge construction projects, which incur PE costs that are relatively higher than those required for other highway project types. However, given the uncertainties in the planning phase, it is challenging to estimate PE costs effectively and efficiently. The purpose of this study was to provide DOTs with a PE cost estimation method using different ratios of PE cost to construction cost for bridge projects by project type and size. To that end, the study tested the variability of PE costs by analyzing 628 Texas DOT bridge construction projects divided into three project types: bridge maintenance (BMN), bridge replacement (BR), and bridge widening and rehabilitation (BWR). The analysis found that the ratios of PE cost to construction cost for the BMN and BR project types were significantly different by project size, but was not conclusive for the BWR project type because of limited sample size. The validation results indicate that the proposed method is effective for planning and estimating the PE costs of a portfolio of projects. The study findings can provide DOTs with an improved PE cost estimation process for a portfolio of bridge projects during the project planning phase.