State DOTs (department of transportation) spend billions of dollars on construction and maintenance of transportation projects every year. In addition, significant sums go to preliminary and construction engineering (PE and CE). For many projects, DOTs utilize engineering services from consultants, to supplement in-house engineering. The cost and quality of consultant’s engineering services compared to in-house, are important issues to justify the involvement of consultants. This report provides an analysis of those issues on Texas Department of Transportation (TXDOT) projects. Traditionally, the costs of PE and CE are calculated as a fixed percentage of total project construction cost, and the efficiency of engineering organizations is assessed by comparison of their gross percentages. However, the results presented here show that project scope and complexity are significant factors in PE and CE cost. Therefore, simplistic comparisons of PE and CE percentages can be misleading when applied across a mixed program of projects. / text