The objective of this project was to render the Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) road assessment methods accessible to field engineers through a software package with a graphical user interface. The software implements both methods more effectively by integrating the complementary nature of
GPR and FWD information. For instance, the use of FWD requires prior knowledge of pavement thickness, which is obtained independently from GPR.
Performance-Based Measurement of Optimum Moisture for Soil Compaction
Part of the challenge achieving maximum field density in subgrade materials is transferring the optimal compaction and moisture content data from laboratory testing to the field. This research investigated the proficiency of four different instruments at accurately predicting moisture contents of three subgrade soils (loam, silt, silty/clay) commonly used in Minnesota roadway construction projects. The four instruments were; DOT600 (moisture content), WP4C dewpoint potentiometer (matric suction), the Button Heat Pulse Sensor (BHPS) (temperature rise vs. moisture content), and an exudation pressure test device.
Improved Approach to Enforcement of Road Weight Restrictions
This project focused on the enhancement and evaluation of a battery-less wireless weigh-in-motion (WIM) sensor for improved enforcement of road weight restrictions. The sensor was re-designed in this project so as to reduce its height, allow it to be installed and grouted in an asphalt pavement, and to protect the piezo stacks and other components from heavy shock loads. Two types of software interfaces were developed in the project: an interface from which the signals could be read on the MnDOT intranet; and an interface through a wireless handheld display. Tests were conducted at MnRoad with a number of test vehicles, including a semi tractor-trailer at a number of speeds from 10 to 50 mph.
2013-26 Friction Measurement System for Polk County
A friction measurement system was developed for Polk County and installed on two snowplows in the county’s winter road-maintenance fleet. The major components of the developed system were a special instrumented wheel, a pneumatic pressure-controlled cylinder, force-measurement load cell and accelerometers, a data collection microprocessor and a data processing micro-processor. The almost identical installations on the Polk County trucks suffered bearing failures after the first few days of continuous use. The failed bearings were replaced with larger bearings in a more robust mount. Apparently, the system again failed in a few days. The low budget for the project and the significant travel required to go to Crookston posed major challenges in getting a friction measurement to work effectively for Polk County.
2013-25 Toolbox of Countermeasures for Rural Two-Lane Curves
The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a priority for national, state, and local roadway agencies. Horizontal curves are of particular interest because they have been correlated with increased crash occurrence. This toolbox was developed to assist agencies address crashes at rural curves. The main objective of this toolbox is to summarize the effectiveness of various known curve countermeasures. The toolbox is geared toward rural two-lane curves. The research team identified countermeasures based on its own research, through a survey of the literature, and through discussions with other professionals.
2013-24 The Minnesota Bicycle and Pedestrian Counting Initiative: Methodologies for Non-motorized Traffic Monitoring
The purpose of this project was to develop methodologies for monitoring non-motorized traffic in Minnesota. The
project included an inventory of bicycle and pedestrian monitoring programs; development of guidance for manual,
field counts; pilot field counts in 43 Minnesota communities; and analyses of automated, continuous-motorized
counts from locations in Minneapolis. The analyses showed hourly, daily, and monthly patterns are comparable
despite variation in volumes and that adjustment factors can be used to extrapolate short-term counts and estimate
Best Practices Synthesis and Guidance in At-Grade Trail-Crossing Treatments
At-grade trail crossings have frequently been the sites of bicycle, pedestrian, and snowmobile crashes in
Minnesota and throughout the nation. To date, many resources exist for use in the design of trails and
intersections, such as the MnDOT Bikeway Facility Design Manual, while guidelines of traffic control at
roadway-trail crossings are covered in the MN MUTCD. Resources on comprehensive guidance for safety
treatments at roadway-trail crossings, however, are limited. The goal of this document is to synthesize best
practices observed statewide in Minnesota and nationally in order to provide engineers and other
transportation professionals with guidance on safety treatment applications at trail crossings. Following
discussion of principles of user-friendly trail-crossing designs, this document provides a toolbox of
categorized treatments which are widely used in the U.S. with discussion on each treatment. Importantly, a
decision tree-based treatment selection methodology is developed for fast look-up and selection of
appropriate treatments based on the conditions at a particular trail crossing. These conditions include
urban/rural setting of the crossing, number of lanes of the crossed roadway, whether the crossed roadway is
divided or undivided, the speed limit and average daily traffic (ADT) of the crossed roadway, and whether
the crossing is a midblock or parallel path crossing. Each end node of the decision tree leads to a specific
toolbox in table form containing all appropriate treatments for the conditions of the study trail crossing.
Final treatments for the study site can be simply chosen from the table, combined with site-specific
requirements and engineering judgment.
2013-22 Best Practices for Pedestrian/Bicycle Safety
The information in this Best Practices Guide is provided as a resource to assist agencies in their effort to more safely accommodate pedestrians and bicyclists on their systems of roads and highways. The information here is consistent with best practices in safety planning as presented in guidance prepared by the Federal Highway Administration, the American Association of State Highway and Transportation Officials and the National Cooperative Highway Research Program. This information is provided to agencies in an effort to reduce the number of severe crashes with pedestrians and bicyclists on their roadway systems, and it is understood that the final decision to implement any of the strategies resides with the agency. There is no expectation or requirement that agencies implement any specific safety strategies, and it is understood that actual implementation decisions will be made by agency staff based on consideration of safety, economic, social, and political issues and location-specific considerations.
The objective of
this research project was to investigate the possibility of putting the brick to beneficial use as aggregates for base
courses in pavements. This would help to conserve natural stone aggregate and also recycle the brick instead of
dumping it as waste in a landfill. In addition, contractors could save money by being able to reuse locally available
material. MnDOT is already quite progressive in its use of recycled materials and allows the use of recycled
concrete aggregates, recycled asphalt pavement, and recycled glass in base and surface courses. Based on current
literature review, Minnesota may become a pioneer in the use of recycled brick aggregate as well.
2013-20 Use of Tire Derived Products (TDP) in Roadway Construction
Tire Derived Aggregate (TDA) is referred to in this report as rough shreds, shreds, and tire chips of various sizes.
The potential uses discussed herein include TDA as lightweight fill, retaining wall backfill, insulation layer,
drainage layer, and capillary moisture break. Other uses exist; however, they are beyond the scope of this report.
This report summarizes the results of numerous studies regarding the environmental concerns of using TDA both
above and below the ground water table. The summary provides general observations based on the literature review
performed, comments on the current state of the practice regarding the use of TDA for highway applications, and
information on additional resources.
Extending the Twin Cities Cyclopath Tool to Enable Multimodal Routing
Researchers incorporated multimodal routing into the Cyclopath bicycle route-finding tool to allow users to find routes that combine biking and transit for journeys where biking alone is impractical. Increasing the percentage of trips made by methods other than cars is a MnDOT priority, and providing route information can help to make alternative transportation options more viable.
PCC Surface Characteristics - Rehabilitation MnROAD Study
This report describes an extensive data collection effort, spanning five years, and the subsequent data analysis to
evaluate the performance of surface characteristics on portland cement concrete pavements that have been diamond
ground with various grinding configurations. The data collected were analyzed and evaluated to observe the longterm
performance of the surface characteristics of noise, friction, texture, and ride quality.
Improving Traffic Signal Operations for
Integrated Corridor Management
In this project, a maximum flow
based control model was first developed to handle oversaturated traffic conditions at signalized arterials. Based on
the arterial control model, an integrated control model was proposed to manage network congestion. Through
diversion control, the model aims to fully utilize the available capacity along parallel routes. The impact of the
diversion traffic is considered, especially for signalized arterials, so that traffic congestion on the diversion route
can be reduced or eliminated by proper adjustment of signal timings.
Pavement Texture Evaluation and Relationships to Rolling Resistance at MnROAD
Measurements of pavement surface texture were conducted on the test cells at the MnROAD research facility. The testing was performed using a mobile, line-laser-based texture profiler that provides results in both the longitudinal and transverse directions. In addition to common texture metrics — for example, mean profile depth (MPD) — a variety of other metrics are calculated and reported. This includes the texture level in third-octave wavelength bands (the texture spectrum) and metrics that can distinguish between upward and downward oriented texture (for example, skew). These texture metrics are combined with other pavement surface characteristics measured on the same MnROAD test cells into a single database. The other surface characteristics are coefficient of rolling resistance (CRR), roughness, friction, and tire-pavement noise. Using the results in the database, multivariable linear regression analyses are conducted to investigate the dependency of the CRR on the other surface characteristics. The performance of the various regression analyses is compared and variable combinations yielding good performing models for CRR are presented. Among the conclusions is that many possible combinations of surface characteristic variables are shown to be eligible for a model to predict CRR.
Recycled Asphalt Pavement: Study of High-RAP Asphalt Mixtures on Minnesota County Roads
This report summarizes lessons learned about the field performance of local roads containing Recycled Asphalt
Pavement (RAP) and associated field and laboratory work with asphalt activation as well as the design and
performance testing of high-RAP bituminous mixtures.
Mobility Performance Measures for Arterial Streets
Researchers used commercially available GPS travel speed data for arterial streets in the Twin Cities Metropolitan Area to develop performance measures as well as performance targets based on context and land use. MnDOT will ultimately be able to use this data as it works to address congestion on arterial streets. Researchers also identified the most congested arterial streets in the metro area.
Mitigating Highway Construction Impacts Through the Use of Transit
Researchers examined how transit could be used to mitigate the impact of a major and highly disruptive road construction project in Duluth, Minnesota, as well as the factors that determine whether people who switch to transit during the construction project continue using it when the project is completed. Research indicated that once a disruptive event induced drivers to try transit, they tended to stay with it as long as that service remained adequate to their needs.
Wakota Bridge Thermal Monitoring Program Part II: Data Analysis and Model Comparison
In this work, a common refined design method is evaluated with respect to a recently constructed bridge. Two
finite element models of the Wakota Bridge in South St. Paul, Minnesota were produced using a design level
program (SAP2000). These models were analyzed and their results compared to the data collected from the bridge.
The second half of this study concerned the comparison of the collected field data with the values produced by
evaluating the design-level finite element models previously created in Phase I of the project, and calibrating these
models to provide an accurate prediction of the future behavior of the bridge.
Wakota Bridge Thermal Monitoring Program Part 1: Analysis and Monitoring Plan
In this work, a common refined design method is evaluated with respect to a recently constructed bridge. Two
finite element models of the Wakota Bridge in South St. Paul, Minnesota, were produced, one using a design level
program (SAP2000) and the other using a research level program (ABAQUS). These models were verified with
respect to each other using linearly elastic materials and were found to behave similarly. After this verification, an
arbitrary temperature load was applied to each model and the refined design method was evaluated for accuracy of
reduced section properties with respect to the more descriptive progressive cracking solution simulated by
Using Concrete Maturity Testing to Optimize Road Opening Timing
Researchers developed strength-maturity relationships in concrete that allow contractors, field personnel and materials engineers to reduce the sampling and testing necessary to estimate the strength of concrete pavement mixes that have high supplementary cementitious materials content and low water-cement ratios. Overall results showed that MnDOT can use the maturity method to accurately predict the strength of portland cement concrete. Researchers also developed a database of concrete mixes and their associated maturity curves, created a draft construction specification and produced a draft laboratory manual detailing the use of maturity curves for portland cement concrete pavement construction projects.
2013-09 Synthesis of Bridge Approach
Panels Best Practices
Joints between the approach panel and the pavement on integral and semi-integral abutment bridges in Minnesota often fail prematurely due to compression and expansion from the state's wide temperature swings. This project surveyed nearby state and provincial transportation departments to learn their practices for these types of joints. Strip seals, neoprene compression seals from D.S. Brown and Sealtite polyurethane foam are recommended for further consideration in Minnesota.
Stripping of Hot-Mix Asphalt
Pavements under Chip Seals
Researchers conducted a survey, tested field samples in the laboratory and reviewed construction methods to determine why hot-mix asphalt pavement stripping occurs in some Minnesota streets after placement of asphalt chip seal, and to determine methods for preventing and remedying stripping. Results suggest that stripping is caused by variability in density due to inadequate compaction, and it can be prevented by using a nuclear density gauge to qualify candidates for chip seals and by taking random core samples from pavements during rolling.
Understanding the Economic Effects of Flexibility through Three Employer Case Studies
Broader business acceptance of flexible workplace policies would reduce congestion and make more efficient use of roadways. This study attempted to validate these policies from a business perspective through three case studies of flexible workplace organizations. Both employees and managers described the policies as resulting in reduced turnover and improved productivity with increased employee satisfaction. Although economic benefits can be inferred from these factors, they were not directly observed.
Research Implementation of the SMART-SIGNAL system on Trunk Highway (TH) 13
Investigators upgraded the SMART-SIGNAL (Systematic Monitoring of Arterial Road Traffic and Signals) system by making field hardware more compact and easier to install. They also developed a Web-based interface for traffic control center software, allowing the generation of real-time arterial performance measures and historical statistical reports. Investigators implemented the refined system at 13 intersections along Trunk Highway 13 in Burnsville, Minnesota.
Quality of Life: Assessment for Transportation Performance Measures
. This project sought Minnesota citizen input through focus groups and mail surveys to define quality of life, identify the role transportation-related factors play in it and investigate how MnDOT is performing on those factors. Accessibility, safety, maintenance and mobility were rated the most important factors. Overall, Minnesota residents were fairly well-satisfied with MnDOT services, with 84 percent rating performance at least 5 on a 7-point scale.
Investigators installed 55 energy-efficient streetlights along a section of 46th Street in south Minneapolis. This project evaluated the cost-effectiveness and lighting quality of both LED and induction light technologies, and compared products from several manufacturers and vendors. LED streetlights were found to provide adequate lighting quality. This technology may soon be cost-effective for general use.
2013-03 Case Studies of Transportation Investment to Identify the Impacts on the Local and State Economy
? Four case studies of transportation projects were evaluated to determine their impact on local economic activity. Researchers found no evidence of statistically significant impacts on earnings and employment, although a broader evaluation of user benefits may be appropriate in determining their value. These case studies support the suggestion that highway networks in the United States are largely mature, and new investment is subject to diminishing economic returns.
2013-02 Design and Construction Guidelines for Thermally Insulated Concrete Pavements
Researchers performed life-cycle cost analysis comparisons and developed design and construction guidelines for thermally insulated concrete pavements (TICPs). They also examined the applicability of the Mechanistic-Empirical Pavement Design Guide (MEPDG) and California models to TICPs. Results uncovered significant issues with the MEPDG’s climate model, leading to recommended corrections. Researchers developed their own models and a software companion to the MEPDG that incorporates the models. The final report includes construction guidelines for composite pavements and a life-cycle cost analysis comparing the costs of TICPs with jointed plain concrete pavements.
2013-01 Instrumentation of Navistar Truck for Data Collection
The overarching goal of this project was to instrument the new MnDOT Navistar truck used at MnROAD. A rugged data acquisition, data recording and wireless transmission system was established for collection of various sensor signals from the truck. The truck was instrumented with a suite of 20 accelerometers, with these accelerometers being located both on the five axles of the truck and on the tractor and trailer bodies. In addition, the truck was instrumented with a differential GPS system and an inertial measurement unit in the tractor cab. A cRIO-based data acquisition system, a rugged laptop and Labview software together serve as a flexible platform for data acquisition. The above instrumentation of the truck will enable data collection on truck vibrations, enable analysis of correlations between truck vibrations and variations in signals of weigh-in-motion sensors, and enable recording of truck movements and pavement loads at MnROAD.
Complete Streets Implementation Resource Guide for Minnesota Local Agencies
Investigators developed a guide to help local agencies implement Complete Streets programs, including sample policy language from agencies in Minnesota, systems for classifying roadways that are appropriate for use in context-sensitive planning and a worksheet to help develop specific project plans.
Aggregate Roads Dust Control: A Brief Synthesis of Practice
Researchers developed an easy-to-use guide about dust control options for unpaved roads, based on surveys and a literature search. While calcium chloride and magnesium chloride are the most commonly used dust suppressants, the report highlights the benefits and drawbacks of several options and includes a host of other published resources.
Pooling Our Research: Updating Precipitation Frequency Estimates
The National Oceanic and Atmospheric Administration has updated precipitation frequency estimates for Midwestern states, making them available as NOAA Atlas 14, Volume 8. These estimates are used to design small drainage structures such as inlets, storm drains and small culverts. In some cases, precipitation estimates have changed significantly and will have a marked impact on the way MnDOT designs hydraulic infrastructure.