November 2018 Vol. 6, No. 8

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Biobased sealant for bridge decks tested in Hutchinson

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Photo: LRRB

Most bridge sealants are quite toxic and contain many compounds that can be dangerous. The City of Hutchinson wanted a more environmentally friendly and operator-friendly option for sealing bridge decks. It received a grant from the Minnesota Local Road Research Board (LRRB) Local Operational Research Assistance (OPERA) Program to test a biobased product. A fact sheet is available about the work.

City staff chose to use an Opti-SEAL™ product from BioSpan Technologies because it is 90% biobased. The sealant was placed in three applications. Two areas of the bridge were left untreated to allow for comparison.

To test the material, staff sealed large rain-gauge tubes to treated and untreated areas at opposite ends of the bridge to measure water loss. After installing the tubes, crews measured results two days later and again six days later. This testing was done one month after the sealant was applied. The test helped corroborate the city’s expectation that there would be a benefit to sealing the bridge deck. Observations taken one year later also corroborated the expectation.

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Extreme winter storm response requires planning, coordination


As severe winter storms become increasingly common and potentially more disruptive, state DOTs are responding with planning that goes beyond routine winter maintenance activities. Based on six case studies, Clear Roads researchers found that agencies with effective response plans for severe winter weather employ a transportation emergency management office, facilitate interagency cooperation, and embrace technologies for tracking and reallocating equipment.

Severe winter storms may not cause damage as acute as that from hurricanes, tornadoes, or flooding, but they can affect larger geographic areas for longer periods of time, impeding mobility on a regional scale. Winter storms have become more frequent and intense since the 1950s, and the northern United States expects increasing extreme precipitation in the coming decades, according to the report.

From the six case studies, investigators distilled recommended best practices and grouped them into two categories: organization and communication, and planning, training, and review. A key finding is that the agencies profiled in this study all assigned a transportation office or official to lead emergency operations in response to severe storms.

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Design tool offers alternatives to protect pavements from frost damage

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Since 1995, MnDOT has required frost-free materials—coarse gravel, sand, and other materials—in asphalt pavement subgrades at depths of 30 to 36 inches, based on load requirements. Whether this practice was effective at all locations was unclear, however, and sometimes it was unnecessary. To determine necessary requirements, researchers studied 72 Minnesota sites to develop pavement profiles. A new design tool is one result of the study.

“Frost protection has not been studied in depth recently,” says lead researcher Matthew Oman, principal engineer with Braun Intertec Corp. “This research used inputs based on soil type, location, and expected frost depth, and didn’t require advanced modeling or expensive laboratory testing.”

The spreadsheet tool uses project location (latitude and longitude), predicted frost depth, and subgrade soil silt content as the key factors in frost susceptibility of pavements. The tool recommends frost-treatment ranges from about 30 percent of predicted frost depth for soils with zero silt to over 80 percent of predicted frost depth for soils with 100 percent silt.

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Unmanned aerial systems: EDC-5, MnDOT research

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Unmanned aerial systems (UAS), also known as drones, can benefit nearly all aspects of highway transportation by collecting high-quality data automatically or remotely. They are one of the innovations on tap for round 5 of Every Day Counts and the topic of ongoing MnDOT research.

UAS are multi-use aircraft controlled by a licensed operator. They replace boots on the ground, increase accuracy, speed up data collection, and provide access to hard-to-reach locations.

Four Minnesota counties started to use UAS this past summer, says Joe Campbell, transportation engineer/assistant bridge engineer with the FHWA’s Minnesota division. “A huge benefit is increased safety,” he says. “A drone in the air is one less person on a ladder or steep slope.” Use is spreading as agencies realize how easy drones are to use, the valuable data they can collect, and their relatively inexpensive cost, he adds.

MnDOT is continuing to develop UAS expertise for bridge inspection. A recent report found that using UAS can reduce inspection costs by up to 40 percent compared to using traditional methods.

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AASHTO TC3 library provides online training

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The FHWA and the American Association of State Highway and Transportation Officials (AASHTO) finalized an agreement that provides local and tribal transportation professionals access to the AASHTO TC3 library. The AASHTO TC3 catalogue provides more than 120 courses and some of the best online training available anywhere.

AASHTO’s goal with TC3 is to create and maintain a fully optimized curriculum to respond to the changing needs of the transportation technical workforce. Courses provided by TC3 are developed through a collaboration of national best practices and a network of knowledgeable subject matter experts.

If you are a transportation practitioner working for a local or tribal government and want to improve your construction, maintenance, and material selection processes and projects, please take the opportunity this agreement provides.

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Chloride pollution: A music video


Three University of Minnesota professors created a music video about chloride pollution. The video serves as an upbeat how-to guide on using less salt while still preventing icy sidewalks and driveways.

In addition to their day jobs, the trio—Mark Pedelty, Tim Gustafson, and Robert Poch—form The Hypoxic Punks, an environmentally conscious folk-punk band spreading eco-friendly messages.

The fun music video shows how salt gets from roadways into our rivers and lakes, and what people can do about it. The Mississippi Watershed Management Organization awarded a mini-grant to the trio to help pay for professional videography, video editing, and sound recording and editing.

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