When applying the Mechanistic-Empirical Pavement Design process, which of the following is established first?

• A. Input data collection
• B. Performance criteria thresholds
• C. Trial design selection
• D. Evaluation of trial design

Answer: (A)

In the Mechanistic-Empirical Pavement Design process, the first step involves input data collection. This step is essential because it lays the groundwork for all subsequent analyses and decisions in the design process. Input data includes information on materials, environmental conditions, traffic loads, subgrade properties, and existing pavement conditions. Without this comprehensive collection of data, it would be impossible to accurately assess performance requirements or evaluate design options.

Establishing a solid foundation of input data ensures that subsequent phases, like setting performance criteria thresholds, trial design selection, and evaluation of trial design, have reliable and relevant information to work with. Each of these later steps builds upon the data collected initially; hence, it is critical to prioritize this step in the design framework.