Sensitivity analysis of the mainline travel lane pavement service life when utilizing part-time shoulder use with full depth paved shoulders

Part-time Shoulder Use (PTSU) is an Active Traffic Management (ATM) strategy that utilizes the shoulder as an additional travel lane during high congestion periods to temporarily increase roadway capacity. This strategy has become increasingly popular on freeways around major metropolitan areas in the United States (U.S.) and Europe. This research focused on freeways near major metropolitan areas where the roadways are structurally sound, but widening roadways has become increasingly expensive to implement. These areas typically utilize full-depth paved shoulders, defined as shoulders built to the same pavement structural profile as the mainline travel lanes and structurally sufficient to carry heavy vehicle loading. As a result of PTSU, the load repetitions on the mainline travel lanes can be reduced for multiple hours during each day by shifting vehicles to the shoulder and this load reduction may indirectly increase the mainline pavement's service life. This research explored the potential benefits of PTSU based on a variety of conditions, including climate conditions, pavement types, and traffic loading levels. The results suggest that across all of these conditions an extension of 10-20% in service life can be expected for both flexible and rigid pavements in the mainline travel lanes.