The Quarterly Journal of the County Road Association of Michigan
INVENTORY-BASED RATING SYSTEM PILOT TESTED IN 2016 HOW DO INVENTORYBASED RATINGS WORK? The uniform PASER road rating system used across most of the US doesn’t work for unpaved roads because their conditions literally change with the weather and how recently the grader has run down the road. The new IBR system developed by Michigan Tech’s CTT has determined that three primary conditions correlate with the condition of an unpaved road: g Surface width, detailing travel width and shoulder width, measured in feet; g Drainage adequacy, assessing the presence or absence of a secondary ditches for draining, and the road’s surface water retention; and
Unpaved road rating system developed by Michigan Tech brings asset management principles to unpaved Michigan roads FINALLY – THE TOOLS TO RATE AN UNPAVED ROAD Gravel and unpaved roads make up half of Michigan’s nonfederal aid network, and there are 22,000 miles of them in Michigan. While the national Pavement Surface Evaluation and Rating (PASER) system works well for rating and assessing surface conditions of asphalt, concrete and sealcoat roads, it doesn’t work for ever-changing unpaved roads. Unpaved road surfaces vary widely. A significant rain, heavy traffic, ice and other factors can change the surface condition dramatically.
g Structural adequacy, which considers large potholes and gravel depth.
As a result, finding a metric system to rate unpaved roads has proved elusive until very recently.
Each IBR category is measured by a specific set of values that are easy to identify. Raters use Good, Fair or Poor for each.
In the last few years the staff at Michigan Technological University’s Center for Technology and Training (CTT) have been working to solve this problem. As a result of a project funded by the Michigan Transportation Asset Management Council
(TAMC), CTT has pioneered a new rating system for unpaved roads, called the inventorybased ratings (IBR) system. In early 2015, CTT went searching for a wide variety of county road agencies willing to pilot the new rating system on some of their unpaved roads, and help tweak it to be effective for efficient assessment of this important road asset. Five county road agencies volunteered for the pilot: The Antrim County Road Commission (ACRC), Baraga County Road Commission (BCRC), Huron County Road Commission (HCRC), Road Commission of Kalamazoo County (RCKC) and the Van Buren County Road Commission (VBCRC). THE RESULTS ARE IN! After using IBR for unpaved roads, pilot agencies are optimistic about the future of rating unpaved local roads. Doug Mills, PE, BCRC engineer-manager, said unpaved roads conditions have been tough to assess objectively
over the years due to changing surface conditions. “Somehow, some way, county road agencies need to quantify the condition and needs of unpaved roads,” said Mills. “Because things change so frequently, systems that were in place for other assets were inadequate. IBR has changed that, giving us a great starting point for future improvements.” As a rural county with around 260 miles of unpaved roads, VBCRC has been rating all of the roads in its jurisdiction since 2010. Following the pilot IBR rating period, VBCRC account clerk Linnea Rader, said that “rating gravel roads with the IBR system provides a better way to prioritize maintenance and reconstruction efforts similar to that of the asphalt system.” With funding limiting county road agencies’ ability to upgrade unpaved roads to pavement anytime soon, it’s important to have a rating tool to establish the true funding need to maintain unpaved roads and to allow a true asset management approach to managing them. Crossroads