The study looked at highway construction projects to see how often costs go over budget and by how much. They found that bigger projects and longer contracts are more likely to have cost overruns. The amount of the cost overrun is not always directly related to the size of the project. On average, the Indiana Department of Transportation can expect a 7.59% cost overrun on almost half of its projects, and a 1.29% cost underrun on over 40% of its projects. This research helps agencies better estimate how much money they might need for unexpected costs in highway projects.