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Project Details
STATUS

In-Progress

START DATE

08/20/19

END DATE

07/31/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Vern Schaefer

Interim Director, CEER

About the research

The Minnesota Department of Transportation (MnDOT) issued a tech memo in 2015 assigning a granular equivalent (GE) factor of 2.0 to multi-axial geogrids. Due to the advance of geogrid materials, this GE value may underestimate the performance benefit of geogrids, resulting in overdesigning the thickness of aggregate base layers. The mechanistic-empirical flexible pavement design program, MnPave, does not currently contain a geogrid design module. City engineers in Mankato have used geogrid manufacturer’s design methods (e.g., Tensar’s SpectraPave4-PRO) as an alternative to analyze and design such pavement structures. However, this causes an inconsistency of standards and methodologies in pavement structure designs and difficulties in quality control and quality assurance (QA/QC) testing of roads systems. The cost analysis shows that in some projects, the geogrids can reduce the thickness of aggregate base and asphalt top to make it a more cost-effective solution. A good example is Madison Avenue between Victory Drive and Trunk Highway 22 in Mankato that the city constructed around 2012.

The objective of this project is to evaluate the performance benefit and cost effectiveness of geogrid in road systems by addressing five questions: (1) What strength enhancement is offered by the use of geogrids? (2) In which layer in a pavement structure is geogrid most effective? (3) How should geogrids be in the MnPave software application? (4) How would it be possible to evaluate the effectiveness and reliability of proprietary geogrid design? (5) How would it be possible to evaluate cost versus benefits of geogrids in different soil conditions?

Project Details
STATUS

In-Progress

START DATE

08/07/19

END DATE

06/30/22

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Chris Rehmann

Assistant Professor

Co-Principal Investigator
Kaoru Ikuma
Co-Principal Investigator
Michael Perez

About the research

The research (field study) will assess persistence of KAc in soil and water, effects on biochemical oxygen demand (BOD) and dissolved (DO), and toxicity to flora and fauna.

Project Details
STATUS

In-Progress

START DATE

04/15/19

END DATE

10/31/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Başak Aldemir Bektaş
Co-Principal Investigator
Katelyn Freeseman

Associate Director, BEC

About the research

White-Nose Syndrome (WNS) is estimated to have killed more than 5.7 million bats in eastern North America since it was identified in New York in 2006. Due to WNS and increased disturbance of habitats used by bats for roosting and foraging, there has been a growing concern about the bat population in the United States in the last decade. Due to the steep decline in bat population, the U.S. Fish and Wildlife Service (USFWS) listed the northern long-eared bat (Myotis septentrionalis) as threatened under the federal Endangered Species Act in 2015. Additional bat species are anticipated to be listed in the coming years.

During the summer months, bat species may utilize bridges as day-time roosting habitat, and may also use them as places to form maternity colonies where they give birth and raise their young. Bridge repair and replacement projects are required to follow additional regulatory requirements to avoid and minimize impacts to the bats, when protected bat species are present on bridges. Some of these requirements (e.g., timing restrictions) are challenging to implement given Minnesota’s short construction season. This project seeks to evaluate the feasibility and efficacy of deploying non-lethal ultrasonic acoustic devices in the field to temporarily deter bats from roosting on bridges ahead of construction or maintenance activities, while minimizing harm to bats and non-target species. Test sites will be located in Minnesota or areas with similar bat species and habitats.

Project Details
STATUS

Completed

START DATE

10/11/18

END DATE

05/29/20

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, BEC
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

About the research

Throughout the US, many state departments of transportation (DOTs) are experiencing issues with the loosening of anchor bolt nuts on overhead sign, luminaire, and traffic signal (SLTS) structures. Retightening loose nuts imposes a significant drain on state DOT resources. In addition, loosening of these nuts increases fatigue stresses on the anchor bolts, possibly increasing the risk of failure.

Loose anchor bolt nuts were recorded on both old and new structures, some immediately after installation. Even after retightening by Minnesota Department of Transportation (MnDOT) maintenance workers, anchor bolt nuts were found to come loose within two years. In a previous project, new retightening specifications were developed based on laboratory testing, field monitoring, surveys of current practices, and finite element modeling.

This project focused on implementation and evaluation of the proposed specifications from the previous project. Structural monitoring also continued on a previously instrumented overhead sign structure. Difficulties were discovered with the proposed procedures during implementation, including structure clearance, instruction clarity, and retightening timing. Overall, though, the proposed procedures were found to be effective in preventing loosening. Revisions to the specifications were suggested along with recommendations for further review to simplify the procedures through a future laboratory study.

Project Details
STATUS

Completed

START DATE

06/14/16

END DATE

01/31/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

Co-Principal Investigator
Bora Cetin
Co-Principal Investigator
Kasthurirangan Gopalakrishnan

Associate Director, PROSPER

About the research

Concrete grinding residue (CGR) is a slurry waste consisting of water and concrete fines generated from diamond grinding operations that is used to smooth a concrete pavement surface. During this process, CGRs are mostly disposed along the roadside, which can influence soils and plant communities along the roadways. To understand the effects of CGR on soil physical and chemical properties and plant growth, a controlled field site at the Kelly Farm in Iowa was used with CGR application rates of 0, 10, 20, and 40 dry ton/acre to test properties of soils and plants before the application and one month, six months and one year after the CGR application. Two roadsides along Interstate 90 in Minnesota where CGR material was applied in the past were investigated as well. Laboratory and field experiments were conducted to measure plant biomass, bulk density, hydraulic conductivity, infiltration, pH, electrical conductivity (EC), alkalinity, metals, cation exchange capacity (CEC), exchangeable sodium percentage (ESP), and percentage base saturation (PBS) of soil samples collected from the test sites. Statistical analyses were conducted to correlate the CGR additions to the properties of soils and plants. The results of statistical analyses from the Kelly Farm indicated that CGR material did not significantly affect soil physical properties and plant biomass but impacted the chemical properties of soil. Changes in some soil properties such as pH and percent base saturation (PBS) due to CGR did not persist after one year. The results from two Minnesota roadsides indicated that the areas receiving CGR applications in the past did not negatively affect soil quality and plant growth.

Project Details
STATUS

In-Progress

START DATE

12/21/17

END DATE

02/28/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CP Tech Center
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Peter Taylor

Director, CP Tech Center

About the research

Mixture proportioning generally uses a recipe based on a previously produced concrete, rather than adjusting the proportions based on the needs of the mixture and the locally available materials. As budgets grow tighter and environmental regulations increase, an emphasis on lowering the carbon footprint, is focusing attention on making mixtures that are more efficient in their usage of materials yet do not compromise engineering performance. A means of reducing environmental impact is to reduce the amount of binder in the mixture.

MnROAD is planning to construct several cells using reduced cementitious content mixtures, with the aim of monitoring the constructability and longevity of the concrete. The proposed work has been designed to identify the behavior and performance of concrete paving mixes with low cementitious content, i.e., between 475 to 500 lb/CY, and lower cementitious content, i.e., 430 to 470 lb/CY.

The objectives of this study include:

  • Investigate the early-age characteristics (i.e., placement issues, slow strength gain) of concrete paving mixes containing low and lower cementitious content
  • Assess causes of, or potential for, durability issues with very low cementitious content
  • Identify effect of reduced cementitious content on long term serviceability and economics of concrete pavements (i.e., benefits of reduced shrinkage)
  • Develop recommended specifications, mixing, and placement practices for the use of very low cementitious content concrete paving mixes
Project Details
STATUS

Completed

START DATE

02/21/18

END DATE

05/31/19

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, Iowa LTAP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
David Veneziano

Safety Circuit Rider, LTAP

Co-Principal Investigator
Theresa Litteral

Statewide MDST Facilitator, LTAP

About the research

Connected vehicle technologies hold the potential to produce a number of safety, mobility and environmental benefits. The benefits of connected vehicle technologies are expected to be wide ranging and include reduced crashes, improved mobility and reduced emissions. Local transportation agencies, such as counties and cities can be expected to be affected by the transition to connected vehicle technologies. These agencies can also expect to benefit from connected vehicle technologies, through aspects such as a reduced need to construct roadway infrastructure (fostered by mobility improvements), increased fleet safety (e.g., maintenance vehicles in plowing operations), and other benefits.

However, transitioning highway infrastructure to be ready for connected and autonomous vehicles (CAVs) will ultimately require a significant investment in infrastructure upgrades, new technologies, and power and connectivity. Agencies are already grappling with how and where to invest scarce resources to meet existing needs and addressing CAVs adds an additional burden. As a result, there is a need for local agencies to not only understand what the potential benefits of connected vehicle technologies are, but also how they should be preparing for the transition to such technologies for the infrastructure and fleets that they manage.

This toolbox was developed to provide a summary of information that local agencies should be aware of to prepare for CAVs. The main goal of this toolbox is to assist local agencies in preparing for CAVs in the short term—5 to 10 years. Since local agencies are not generally expected to have the resources to become test beds, this report provides information so that local agencies can leverage ongoing activities and resources to prepare for CAVs.

Project Details
STATUS

Completed

START DATE

04/25/16

END DATE

02/29/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

The Minnesota Department of Transportation (MnDOT) constructed its first glass fiber polymer (GFRP) reinforced bridge deck on MN 42 over Dry Creek just north of Elgin, Minnesota. Successful implementation of the GFRP reinforced bridge decks would eliminate the steel corrosion problems that often shorten the life of the deck. Although there has been wide use of GFRP reinforcement in bridge decks in some parts of Canada, there have been relatively few GFRP reinforced bridge decks built in the United States. The Canadian decks were primarily designed using the empirical design method in the Canadian Highway Bridge Design Code. This method differs significantly from the design guidelines produced by AASHTO and ACI Committee 440 on fiber-reinforced polymer (FRP) reinforcement. To maximize the knowledge and experience gained in constructing this type of bridge decks, this research project investigates the performance of a case-study bridge deck focusing on key issues such as cracking, deck stiffness, load distribution factors, and GFRP rebar strains. The main goals of this project are:

  • Collect behavior information and response characteristics of the bridge deck under service loads
  • Identify the load distribution characteristics, especially for the bridge girders supporting the deck
  • Examine the short-and long-term durability of the bridge deck in terms of formation and propagation of cracks
  • Assess the impact of using non-conventional, corrosion-resistant deck reinforcement on maintenance needs and life-cycle cost with a specific interest in including service-life design philosophies

The outcome of this project will directly contribute to the development of guidance and details for the construction of corrosion-resistant bridges with service lives beyond 100 years.

Project Details
STATUS

In-Progress

START DATE

07/23/18

END DATE

06/30/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Chris Williams

Director, AMPP

About the research

Air void content, specifically at longitudinal joints, is well known as a key factor affecting pavement life. Hot mix asphalt (HMA) pavements historically constructed in Minnesota typically have air voids around 7% in the mat and often approach or exceed 10% directly over longitudinal joints. Mix density is very important in terms of the effect on durability performance in constructed pavements. Higher air voids in the mat, especially over longitudinal joints, leads to poor pavement durability. Poor durability is compounded because water infiltration is increased due to higher air voids, which leads to more required maintenance at longitudinal joint locations and can lead to the need for earlier reconstruction of the pavement. Infiltration of moisture in higher air void joints also leads to reduced strength of underlying pavement layers, which accelerates deterioration when the moisture undergoes freeze-thaw cycling in the pavement structure. Multiple studies show for every 1% decrease in air void content an increase of 10% in pavement life can be achieved. The Minnesota Department of Transportation (MnDOT) has required the use of core measured air voids on projects for many years to monitor achieved air void content in the field. To improve upon current asphalt pavement compaction practices in the state of Minnesota, the research team anticipates datamining historical data to quantify the effect of air void content on pavement performance from confined and unconfined joints through the creation of an air void content database. Improvements will come in the form of modification to current construction practices and/or new standard methods.

Project Details
STATUS

Completed

START DATE

07/23/18

END DATE

12/31/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Chris Williams

Director, AMPP

Co-Principal Investigator
Joseph Poldolsky

About the research

The density and air void content of asphalt mixtures affect the durability and performance of asphalt pavements. Pavement longitudinal joints typically have a lower density than the mat because they receive less compaction than the center section of the mat for various reasons. The higher air void percentages resulting from lower densities can lead to high permeability and allow water infiltration, which in turn can cause moisture-induced damage and decrease base and subbase support to the pavement, reducing pavement life. Void-reducing asphalt membrane (VRAM) has been used at the longitudinal joints of asphalt pavements to achieve higher densities and prevent moisture infiltration, thereby reducing deterioration at the longitudinal joints. VRAM is applied before the hot-mix asphalt (HMA) layer is placed and migrates into the HMA to fill 50% to 70% of the air voids.

This research evaluated the extent to which J-Band, a VRAM product, increases density and improves performance. Field cores were collected from two sections, one with and one without VRAM. Asphalt mixture performance tests, including disk compact tension and semi-circular bend tests, and push-pull tests were carried out in the laboratory on the field-collected specimens. Volumetric measurements were also taken, and ground penetrating radar was used in the field. It was determined that the pavement sections with VRAM had a lower permeability, higher bond energy, and higher fracture energy than the pavement sections without VRAM.

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