Which guide provides instructions on calculating the structural number (SN)?

• A. AAHSTO 1993 PDG
• B. AASHTO 1993 PDG
• C. Highway Design Standards Manual
• D. Federal Highway Administration Guide

Answer: (B)

The correct answer is B, AASHTO 1993 PDG (Pavement Design Guide). This guide provides comprehensive methodologies for the design of flexible and rigid pavements, specifically focusing on how to determine the structural number (SN). The AASHTO 1993 PDG outlines the factors influencing the SN, such as the layer coefficients of the materials used in the pavement structure, the traffic load characteristics, and the subgrade's resilient modulus.

Understanding and using the correct structural number is vital for ensuring that the designed pavement can adequately support the expected traffic loads while maintaining its structural integrity over time. The guide presents detailed equations and procedures for calculating the SN, making it an essential resource for civil engineers working in transportation projects.

Other options may provide valuable information related to transportation engineering but are not specifically focused on SN calculation in the context of the pavement design methodologies described in the AASHTO 1993 PDG.