Concerns with the durability and performance of asphalt concrete that contains recycled materials have recently become the focal point of the asphalt industry. The goal of this research was to improve the performance of asphalt concrete pavements that contain recycled materials in Washington state.

This study was designed to improve the experience of users of Long-Term Pavement Performance (LTPP) data by enhancing the traffic data included in the LTPP database and making it easier for researchers to find and select the traffic data they need for their specific analyses.

Municipalities in the Pacific Northwest are increasingly using pervious concrete pavements (PCP). While this class of pavements offers significant ecological advantages, transportation departments must ensure that the pavements are safe for drivers and pedestrians in the region’s typical adverse winter conditions. To assist transportation departments in implementing more effective winter operations, this study aimed to develop a simple, image-based method to characterize the porosity of PCP.

This project evaluated WSDOT’s current process for calculating highway preservation project costs and benefits and then developed an improved approach. To quantify the regional economic benefits associated with its transportation investment projects, WSDOT uses software developed by the Federal Highway Administration known as the Highway Economic Requirements System—State Version (HERS-ST). The researchers developed a tool to supplement the HERS-ST for benefit and cost estimation processes. The improved method, combining the new HERS-ST-BAT tool with HERS-ST, will allow transportation agencies to more accurately and flexibly estimate changes in their own and user costs resulting from proposed pavement projects and to more effectively consider different investment alternatives.

The growing popularity of pervious concrete (PC) pavement applications has increased the need for establishing its mechanical properties and understanding their relationships with measurable properties for the purposes of designing layer thickness. In this project researchers developed multi-variable linear regression models to predict strength properties for pavement thickness design and developed a recommended thickness design database for low-traffic-volume PC pavements.

This project began development of a database of portland cement concrete material inputs specific to Idaho in preparation for Idaho’s implementation of the AASHTOWare Pavement ME Design software for designing rigid pavements. The Idaho Transportation Department (ITD is transitioning from pavement design procedures based on the AASHTO 1993 Design Guide to AASHTOWare Pavement ME Design (Pavement ME). Pavement ME requires the definition of more than 100 design input parameters. On the basis of this project’s laboratory test results, the report recommends proper values for all PCC Pavement ME material inputs.

The growing popularity of pervious concrete pavement applications, desired for their role in stormwater management and runoff control, has increased the need for development of quality control and quality-evaluation test procedures that are suited specifically for pervious concrete rather than for traditional concrete. This brief study took preliminary steps toward developing appropriate quality control and quality-evaluation test procedures by identifying suitable specimen sizes for testing, proper methods of casting and compacting specimens at the job site, the compatibility of fresh and hardened physical properties, and proper curing methods for compressive strength testing.