This article presents a model to enable managers to make better decisions regarding infrastructure construction management. The model accurately estimates preliminary engineering (PE) costs (synonymous with Preconstruction Services Costs [PCS]) of bridge infrastructure projects so that state, local, and private transportation departments can know what these activities actually cost and can better plan future budgets. It also enables managers of these public works to quickly identify potentially troublesome projects, thus enabling corrective actions to be initiated early. This article describes a comprehensive study of the factors affecting PE costs, a database containing 2001-2009 bridge project data, and models to estimate PE costs. The findings indicate that bridge projects exhibited a historical mean PE cost ratio of 27.8% of estimated construction costs, significantly more than expected or commonly believed.