Partial-depth paved shoulder effect on part-time shoulder use pavement bearing capacity

Abstract

In areas of high population density, widening all classifications of roadways for growing traffic volumes becomes increasingly complex and expensive to complete. For major highways in Europe and the United States (US), use of the shoulder as a part-time lane is becoming progressively common and may be a solution to growing traffic on lower roadway classifications. This approach is known as hard shoulder running internationally and part-time shoulder use (PTSU) in the US. For interstates or other major highways, the shoulder design is a full-depth paved shoulder, the same pavement cross-section as the mainline lanes, and is structurally sound. For arterials and collectors, the shoulder design commonly has a different pavement cross-section from the mainline lanes, a partial-depth paved shoulder design. This study focused on evaluating the design strength of typical partial-depth paved shoulder designs in the US for PTSU using the American Association of State Highway and Transportation Officials (AASHTO) Guidelines for Design of Pavement Structures 1993 design. The study sites were also redesigned according to the AASHTO design methodology to handle the PTSU design traffic volumes. This study found that two of the nine states evaluated could withstand PTSU with minor to no reconstruction.