research | Crossroads

Weigh-in-motion (WIM) systems consist of sensors placed in road pavements to measure the weight of vehicles passing over them, along with other data such as speed, axle load and spacing, and vehicle type. This data is used to enforce weight limits on trucks and is also useful in a wide range of other applications, such as pavement design and traffic analysis.

However, constructing and maintaining permanent roadside WIM stations is expensive, so these systems are installed primarily on roadways with heavy traffic, such as interstate and trunk highways, and rarely used for rural local roads. Meanwhile, heavy truck volumes on local roads are increasing, significantly shortening their lives. A less costly, portable WIM system is needed for such roads so that collected data can be used to better design these roads to accommodate heavy truck traffic.

One solution for bringing WIM technology to local roads is to implement a portable, reusable system similar to pneumatic tube counters used to conduct traffic counts. With funding and technical assistance from MnDOT and the Local Road Research Board, Professor Taek Kwon of the University of Minnesota—Duluth has developed a prototype system that has already proven to be nearly as accurate as the more expensive, permanent systems. MnDOT Research Services staff drove up to MnROAD this week to observe a live demonstration of the technology, and made this short video.

The research being conducted here is part of an implementation project based on Kwon’s original study, the results of which can be found in this research report and its accompanying two-page technical summary from MnDOT Research Services.

As is painfully evident this time of year, Minnesota’s weather is highly destructive to our asphalt roadways. One of the biggest challenges for transportation practitioners in cold-climate states like ours is low-temperature cracking in asphalt pavements. The distress caused by our extreme weather variations and constant freeze-thaw cycles wreaks havoc on our asphalt streets and highways, causing decreased ride quality, increased maintenance costs and shorter pavement lifespans.

On April 17, the Center for Transportation Studies presented its 2013 Research Partnership Award to the team members of a multi-state, Minnesota-led study designed to combat the problem. The project, “Investigation of Low Temperature Cracking in Asphalt Pavements, Phase II,” was a national pooled-fund study involving six state DOTs, four universities, the Minnesota Local Road Research Board and the Federal Highway Administration. It resulted in a new set of tools — test methods, material specifications and predictive models — that will be used to build longer-lasting pavements.

The project is a prime example of the value and benefits of cooperative research. Each organization brought its own unique strengths and expertise to bear on the problem. The University of Minnesota, led by Professor Mihai Marasteanu, brought its strength in lab testing of binders and mixtures, for example; other universities leveraged their respective expertise in data analysis, statistics and modeling capabilities. MnDOT, as the lead state agency, controlled the finances and kept the research on track, guiding the process through technical advisory panels. MnDOT’s materials laboratory and its unique MnROAD pavement research facility also played a key role in the study.

The above video provides an excellent overview of the project and includes commentary from key MnDOT and University of Minnesota team members. MnDOT is already moving to implement the results. It plans to use the new test procedure on several road construction projects this year. Iowa and Connecticut are among the other states reportedly planning implementation projects.