CLOSE OVERLAY
Project Details
STATUS

In-Progress

START DATE

06/04/21

END DATE

06/30/23

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE, Iowa LTAP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
David Veneziano

Safety Circuit Rider, LTAP

Co-Principal Investigator
John Shaw

Researcher, CTRE

Co-Principal Investigator
Jonathan Wood

Faculty Affiliate, CTRE

About the research

In recent years, negative trends have emerged in pedestrian safety. Transportation agencies have sought to address these issues by implementing various pedestrian safety countermeasures at crosswalks and other conflict points.
While effective at improving safety for pedestrians, treatments can present a challenge to winter maintenance operations based on their designs and characteristics.The use of pedestrian safety countermeasures can introduce challenges to snow removal and winter maintenance operations, but misconceptions also exist. For example, one misconception is that people in the suburbs do not walk, and so keeping locations like median refuges clear of snow and ice is a lower priority for agencies.Unfortunately, research has not helped in addressing these issues. Instead, it has largely focused on the mechanics of snow and ice removal: the equipment to use, material application rates, etc., and not the impacts of designs on maintainability and pedestrian safety.
There remains a research need to investigate the best practice guidance and solutions for the design, installation, and maintenance of pedestrian safety features for year-round maintenance. With this in mind, the specific objectives of this research includes:
  • Identify current best practices for designing and implementing pedestrian safety countermeasures for year-round maintainability.
  • Document the design characteristics that make pedestrian safety countermeasures easier to maintain during the winter while using existing MnDOT and local agency equipment.
  • Review MnDOT and select local agency winter maintenance plans, polices, maintenance agreements, and procedures regarding the safety and accessibility of pedestrians and recommend options for agencies to deal with winter maintenance of pedestrian infrastructure.
Project Details
STATUS

In-Progress

START DATE

08/21/20

END DATE

11/30/21

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Chris Williams

Director, AMPP

Co-Principal Investigator
Eric Cochran

About the research

As asphalt pavement oxidizes and ages, bio-materials can be used to restore flexibility to the asphalt pavement. These materials can be used in conjunction with asphalt emulsions to seal and soften weathered pavement. In the current global trade climate, there also exists a need to develop new domestic markets for US agriculture products.

This study investigates further development of using soybean-derived oils to rejuvenate pavement materials. This study is presented with 1:1 matching funds from the United Soybean Board that supports the further formulation and development of a bio-based asphalt rejuvenating fog seal.

The objective of this project is to improve current bio-rejuvenator sealant formulation and achieve stiffness reduction in oxidized, aged asphalt surfaces. The penetration of bio-rejuvenating sealers into the aged-pavement is important for reducing stiffness and restoring flexibility. This research will develop an asphalt emulsion with and without the bio-rejuvenator. The asphalt emulsion will act as the vehicle for the soybean-based rejuvenator. Surface tension reducers for the water-phase will be studied to improve the penetration of the bio-sealant into the asphalt. Particle size of the emulsion is also an important factor for penetration of the bio-sealant. The material developed in this research will be tested at MnRoads on the shoulder of the pavement. Cores will be taken to study the effect of bio-rejuvenating seal on the asphalt. The Minnesota Department of Transportation (DOT) will perform friction testing on the control and test sections to determine the extent surface friction was impacted due to the application of the bio-sealant. The four main steps in this project are (1) bio-sealant emulsion formulation, (2) bio-sealant emulsion application, (3) investigation of stiffness reduction, and (4) studying the effect of the sealant on friction.

Project Details
STATUS

Completed

START DATE

12/30/20

END DATE

08/31/21

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Neal Hawkins

Associate Director, InTrans

About the research

Reduced traffic volumes resulting from COVID-19, along with the strain on enforcement during the pandemic, are thought to have produced higher speeds and more aggressive driving. Understanding the magnitude of speeding and other driver behaviors requires measurement and contrast. This project quantifies reductions in volume and the resulting differences in travel speeds across Minnesota along regular roads and within two work zones prior to and during the novel COVID-19 pandemic. The work includes a review of total crashes as well as fatal and serious injury crashes and includes a survey of law enforcement opinions. Findings based on 125 Automatic Traffic Recorders (ATR) and traffic Sensors quantify volume reductions, which, of course, were lower in 2020 but which varied considerably by location and month. Average speeds overall along with both the number and percentage of vehicles traveling greater than 15 mph over the posted speed limit increased in 2020. This information supports benchmarking and agency decision making.

Project Details
STATUS

In-Progress

START DATE

07/01/19

END DATE

01/31/22

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

Strength and durability of reinforced concrete (RC) bridges are adversely affected by the deterioration of their structural members. When investigating bridges in need of maintenance and repair, deterioration caused by corrosion of steel rebars is commonly found as one of the primary sources of structural degradation, which can eventually result in the service failure of the entire bridge under normal or extreme loading conditions. To ensure the safety of bridges, while reducing direct and indirect costs, an accurate estimate of the extent of reinforcement section loss has a central importance for a wide spectrum of engineers and decision-making authorities. Such an estimate scan be achieved through a systematic effort that benefits from the wealth of available predictive models calibrated with region-specific data and then validated through appropriate field investigations. This directly contributes to improving the predictions made for the remaining structural capacity of bridge elements and subsequently planning protective and/or corrective actions tailored to maintain the bridges in a desired condition state.
Project Details
STATUS

Completed

START DATE

07/01/16

END DATE

08/31/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
An Chen
Co-Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

About the research

Many state Departments of Transportation (DOT) across the US, including MnDOT, are experiencing problems associated with loose anchor bolts used in support structures (e.g., overhead signs, high-mast light tower (HMLT), and tall traffic signals). Specifically, MnDOT inspection crews have found loose nuts at most anchor bolt locations, even at some newly installed signs. Many of these nuts became loose in less than two years, even after being tightened by the maintenance crew following current recommended procedures. This situation has placed great strain on the resources from the districts’ maintenance group and also causes concerns related to inspection frequency and public safety. This project investigated causes of the loose anchor bolts and proposes solutions based on site surveying, field monitoring, laboratory study, and numerical analysis. The research team found that the tightening process proposed in AASHTO’s specification is a sufficient alternative for MnDOT, though it requires modification in three key areas: defining snug-tight, accounting for grip length, and recommending verification procedures. The research team quantified snug-tight values, and defined the relationship between torque, tension, and nut rotation through empirical constants. Recommendations are made for a new specification for MnDOT structures.

Project Details
STATUS

In-Progress

START DATE

10/16/20

END DATE

08/31/21

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
In-Ho Cho
Co-Principal Investigator
Eugene S. Takle
Co-Principal Investigator
Daniel Rajewski

About the research

Over the last several decades, Minnesota’s winters have gotten warmer. In fact, the winters have warmed significantly faster than the summers. Such a trend is forecasted to continue into the foreseeable future. It is possible that this warming trend has increased the length of time spent around the freezing point (32°F), thus also increasing the average number of freeze-thaw events. However, it is also possible that this warming trend has resulted in no change in the number of freeze-thaw events. The proposed research has two primary objectives: (1) to attempt to quantify the number of freeze-thaw events daily, monthly, and annually from historical temperature records, freeze gauges, and other data; and (2) to attempt to collect ground/pavement temperature and study its correlation with air temperature during freeze-thaw events. To achieve these objectives, a two-phase research approach has been developed.

Project Details
STATUS

In-Progress

START DATE

04/05/18

END DATE

03/31/23

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

Co-Principal Investigator
Katelyn Freeseman

Acting Director, BEC

About the research

The Minnesota Department of Transportation is constructing a pair of side-by-side bridges on TH 169, one with GFRP deck reinforcement and the other with conventional epoxy-coated steel reinforcement. Because these two bridges will be exposed to the same environmental conditions, they will experience very similar traffic, and will be constructed within the same timeframe, a unique opportunity exists to identify and evaluate differences in performance between them. Thus, the main goals of the proposed project are to: (1) collect the behavior information and response characteristics of the two bridge decks under service loads, (2) examine the short-and long-term durability characteristics of the two bridge decks, and (3) assess the impact of using non-conventional, corrosion-resistant deck reinforcement on maintenance needs and life-cycle cost. Although there is wide use of GFRP reinforcement in bridge decks in some parts of Canada, there have been only few GFRP reinforced bridge decks built in the US. 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 the American Association of State Highway Transportation Officials (AASHTO) and the American Concrete Institute (ACI). To maximize the knowledge and experience in the use of nonmetallic reinforcement in the bridge decks and understand how the performance and durability of them are compared with conventional decks reinforced with epoxy-coated steel rebars, a systematic effort has been planned for this project.The outcome of this project will directly contribute to the development of guidance and details to construct corrosion-resistant bridges with service lives beyond 100 years.
Project Details
STATUS

In-Progress

START DATE

08/10/20

END DATE

07/31/22

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Nicole Oneyear

Associate Scientist, CTRE

Co-Principal Investigator
David Veneziano

Safety Circuit Rider, LTAP

Co-Principal Investigator
Hossein Naraghi

Research Scientist, CTRE

About the research

Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes, representing a significant but poorly understood safety problem. Crashes at rural intersections are particularly problematic when high speeds on intersection approaches are present. Fatal injury crash rates are two times higher in rural than in urban areas. Drivers failing to stop on the minor approach account for 25% of right angle crashes and are more likely to result in injuries than crashes where drivers stopped. Characteristics correlated to failure to yield right-of-way include age, speeding, vision obstruction, and inattention/distraction. Rural intersection crashes in 2018 cost the state of Minnesota an estimated $90,000,000. Transverse rumble strips (TRS) are a low cost countermeasure widely deployed in some states (e.g., Iowa) and have the advantage of being effective in low visibility conditions (e.g., rain, fog, darkness). The primary purpose of TRS are to decrease crashes due to running the stop sign and aren’t generally expected to reduce crashes where inappropriate gaps were selected. However, TRS are often applied at high-crash locations that may lessen their effectiveness if the primary crash type is due to gap selection. Additionally, no consistency exists in the placement or pattern for TRS among or within agencies across the US. As a result, research is needed to assess the effectiveness of TRS and to evaluate whether different designs encourage driver behaviors that may lead to reduced crashes. Design includes placement (location in relation to the stop sign), number of panels (set of grooves), and pattern (i.e., length, number of grooves, distance between grooves).

Project Details
STATUS

In-Progress

START DATE

07/01/20

END DATE

01/31/21

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

As the highway system ages throughout the United States, there is an increasing occurrence of joint associated distress in concrete pavements. This distress can be a result of several factors, including reactive materials, fatigue from vehicle loadings, misaligned dowel bars, poorly drained joint systems, as well as attack from aggressive deicing chemicals. Since the distress occurs primarily near the joints, while the remainder of the slabs are still in serviceable condition, it is often more economical and sustainable to perform joint repairs.

The objective of this project is to produce a short technical brief and webinar containing the best practices for the repair of distressed joints in concrete pavements and overlays, particularly those used in NRRA member states. The techical brief will include causes for the distresses, as well as case histories of successful and non-successful repair methods. A one-hour long webinar will also be developed, delivered, and recorded for future reference.

Project Details
STATUS

In-Progress

START DATE

07/20/20

END DATE

07/31/22

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Minnesota Department of Transportation

Researchers
Principal Investigator
Charles Jahren

Associate Director, Construction Materials and Methods / Asset Management

About the research

The overarching purpose of this study is to provide recommendations for keeping the pavement structure as moisture resistant as possible for the least amount of cost. Required minimum asphalt film thickness (AFT) is an important parameter when assessing the long-term durability of an asphalt mixture. Research shows higher film thicknesses create more durable mixtures. Minnesota specifications require a minimum AFT for mixture design acceptance. If the adjusted film thickness is below acceptable limits during production, large payment reductions or orders to remove and replace may result. Pavement preservation treatments are gaining momentum as cost-effective ways of enhancing pavement life. To prevent deterioration of pavements, chip seals are a proven preservation method and have been widely used in Minnesota. A Minnesota study estimated that a chip seal placed at the time of construction will be cost-effective if pavement life is extended by approximately 0.45 years. Typical life extension for chip sealed roads range 5 to 7 years. The value of AFT specifications has been debated within the paving community. This research offers an opportunity to validate current specifications, investigate the role of chip seals in pavement durability, and use lab and field data to perform a cost-benefit analysis of increased AFT and chip seals placed at 1 year. The objective of the research project is to perform a data-driven cost-benefit analysis of applying higher AFT and/or placing chip seals at 1 year of service. Data for the analysis will be collected from both laboratory performance testing and field performance. Pavement projects especially of interest are projects that incurred pay deductions due to low AFT and if/when chip seals were placed to preserve those roadways.

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