Which of the following is NOT a method for assessing asphalt pavement condition?

Calculating asphalt density is primarily associated with the quality control and production processes of asphalt mixes rather than the assessment of pavement condition. Density measurement typically occurs during the production and laying of asphalt to ensure the mixture meets specified parameters for compaction and material properties.

In contrast, methods like visual inspection, measuring surface roughness, and conducting structural tests are directly focused on evaluating the current state and performance of existing asphalt pavements. Visual inspection provides an immediate assessment of visible distresses, while measuring surface roughness quantifies how smooth or rough the pavement surface is, which can affect ride quality and safety. Structural tests evaluate load-bearing capacity and detect structural damage, contributing to understanding how well a pavement is performing over time. Hence, calculating asphalt density is not a viable method for assessing the condition of existing pavement, making it the correct choice for this question.