Evaluation of MDOT's Long-Life Pilot Projects

As a result of Public Act 175 of 2015 and the Roads Innovation Task Force (RITF) Report, the Michigan Department of Transportation (MDOT) committed to designing and constructing four long-life pavements using hot mix asphalt (HMA) and concrete. The four different long-life pavements are as follows: 30-year HMA on US-131 in the Grand Region, 30-year concrete on I-69 in the Bay Region, 50-year HMA on I-475 in the Bay Region, and a 50-year concrete on US-131 in the Grand Region. In 2017, the first of these pilot projects was constructed (30-year HMA on US-131). In 2018, three more will be let with two being built in 2018 and one in 2019. Several changes were made to standard designs and materials to increase the design life. These include increased structural support (increased layer thicknesses, etc.), improved material selection (HMA binder selection, etc.), improved construction specifications (lower initial ride requirements, etc.), and improved design aspects (increased drainage freeboard, etc.). Before further long-life projects can be planned, an assessment of the potential of the four pilot projects for meeting their intended design and services lives (50 and 75 years) should be performed. An evaluation of the effectiveness of all improvements will help transportation investments on future designs result in longer pavement life.