Measures to improve the accuracy, reliability, and consistency in selecting roughness values for the application of 2D hydraulic models at highway crossings and in transportation corridors will represent a major step forward in the evolving state of practice. Whether a one-dimensional or a 2D modeling approach is taken, inconsistencies can exist from state to state, and even within states at the various district levels, on how to develop accurate and reliable hydraulic models. The fundamental issue is th…