Review of Paved Shoulders

About the report:

The objectives of this study were (1) to review the literature on paved shoulders, (2) to survey state departments of transportation on their use of paved shoulders on two lane roads, (3) to perform a cost analysis on paved shoulders, and (4) to draw conclusions based on the findings. The scope was limited to shoulders made of an asphalt plant mixture used to extend the mainline pavement. The literature review generally supported the notion that paved shoulders are economically justifiable under certain conditions. However, there was no consensus on the specific conditions. The survey results showed that 91.4 percent of the state DOTs surveyed use paved shoulders on two-lane roads to some degree. Most or all shoulders were paved by 42.9 percent of these DOTs, and 40.0 percent have threshold values to warrant paved shoulders. For the average new two- and four-lane road projects, initial cost increases of 16.7 and 8.3 percent, respectively, and a corresponding service life increase of 14.3 percent are realized with 2-ft paved shoulders. For a resurfacing project, initial cost increases of 72.0 and 36.0 percent are realized with a 2-ft paved shoulder on two- and four-lane roads, respectively. Through an economic analysis using the equivalent uniform annual cost method, it was revealed that 2-ft paved shoulders for new two-lane roads are economically justifiable under certain ADT volumes that depend on the road's functional classification and terrain type. Two-foot paved shoulders are not economically justifiable for most existing two-lane roads. For four-lane and six-lane roads, 2-ft paved shoulders are economically justifiable for all new roads and for existing roads above certain ADT volumes.

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