Researchers examined the potential for different combinations of transit and roadway expansion to cost-effectively solve the growing problem of traffic congestion on freeways and expressways in the Minneapolis-St. Paul metropolitan area. They found that a critical factor in the solution is the level of service desired for the roadways.
2006-43 Water Quality Performance of Dry Detention Ponds with Under-Drains
Investigators monitored the performance of three dry detention ponds regarding the amount of suspended solids and phosphorus left behind after storm water drained through them. These storm water management devices performed adequately compared to national standards
2006-42 The Effect of Rumble Strips on Drivers Approaching Rural, Stop-Controlled Intersections
Researchers studied the stopping patterns of approximately 400 cars, trucks and other vehicles at selected rural intersections and found that in-lane rumble strips caused drivers to reduce speeds earlier and to a greater degree than at intersections without rumble strips. This was the third in a comprehensive series of studies on the effectiveness of in-lane rumble strips.
2006-41 Developing ITS to Serve Diverse Populations
In 2003, the State and Local Policy Program (SLPP) at the University of Minnesota's Humphrey Institute of Public Affairs began research into how Intelligent Transportation System (ITS) technologies can be used to deliver transportation services to an increasingly diverse population in Minnesota. The research objective was to identify the nature of the gap between the emerging needs and existing services, and to propose ways of using technology to bridge the gap, both in terms of providing better transportation options and in reducing the cost of these options. Using the information obtained from emerging demographic data, the 2003 study focused on identifying transportation challenges and opportunities for several different populations, with a particular focus on those that do not or cannot drive. This project continues this general theme through a series of analyses of ITS applications that appear most promising to improve mobility and access for Minnesota's increasingly diverse population. These applications include technologically advanced Community-Based Transit, Car Sharing, use of ITS to implement Value Pricing through conversion of an HOV lane to a High-Occupancy/Toll (HOT) lane, and evaluation of web-based Advanced Traveler Information Systems (ATIS).
2006-40 Load Rating of Composite Steel Curved I-Girder Bridges Through Load Testing with Heavy Trucks
Researchers investigated the behavior and load rating of a curved I-girder bridge by load testing the bridge and comparing the results with a grillage-based analysis model. They studied model parameters using the results of the tested bridge and two others tested elsewhere to assess the robustness of grillage analysis for load rating this type of bridge.
2006-39 Mileage-Based User Fee Demonstration Project
The Federal Highway Administration and the Minnesota Department of Transportation co-sponsored a demonstration to test how consumers would change their driving behavior if some of the fixed costs of owning and operating a car were to be converted to variable costs. One hundred and thirty participants were given devices that recorded mileage and time of travel. Prices per mile were assigned randomly to each participant, ranging from 5 cents per mile to 25 cents per mile. The findings indicate that per mile pricing does result in measurable, but small reductions in driving. The largest effect is on weekend driving and on peak weekday travel (as some participants were able to substitute mass transit for their vehicle). One key finding in this experiment is that those households that are willing to change their driving behavior will do so with low per mile cost incentives. On the other hand it was also determined that those households unable to change their behavior do not do so even under relatively higher cost incentives. Therefore, the marginal effect of per mile prices seems to drop off dramatically after some point in the lower range of prices.
2006-38 Minnesota Value Pricing Outreach and Education
The State and Local Policy Program (SLPP) of the Humphrey Institute of Public Affairs, University of Minnesota, in partnership with the Minnesota Department of Transportation (Mn/DOT) and the Metropolitan Council originally designed a project that envisioned extensive research, outreach, and education activities leading to identification and support for a demonstration project by the end of the three year project period. With early acceptance and support for the I-394 MnPASS project by the Governor and Legislature, the Humphrey Institute in collaboration with the Minnesota Department of Transportation and the Federal Highway Administration revised the project to focus on research, outreach, and education activities focused specifically on the I-394 MnPASS project. The major findings of this project are detailed in the summary and supported by the appendices. The appendices include multiple papers submitted to the Transportation Research Board, final reports from the first two waves of the longitudinal panel survey, the community task force report, and an information booklet designed to quickly educate lawmakers.
2006-37 Application of Precast Decks and Other Elements to Bridge Structures
A number of countries have incorporated precast components in bridge superstructures and substructures. Precast components include deck, abutment, and wall elements. Benefits of using precast elements in bridge construction include the high level of quality control that can be achieved in plant cast production compared to field cast operations and speed of construction afforded by the assembly of precast elements at the site rather than the time consuming on site forming and casting required in cast-in-place construction. Key components in the application of precast concrete to bridge structures are the connection elements. Connection details include the use of post-tensioning systems, and various connection details such as weld plates, studs in grout pockets, and shear keys. The Minnesota Department of Transportation (Mn/DOT) constructed a bridge incorporating precast elements to enable rapid construction. The objective of this study was to develop an instrumentation plan to enable investigation of the performance of this bridge. Researchers developed an instrumentation plan based on information provided by the Mn/DOT bridge office regarding the specific bridge details and behaviors to be investigated. The instrumentation plan included the types and locations of the instruments.
2006-36 Beyond Business as Usual: Ensuring the Network We Want Is the Network We Get
Researchers documented construction decision rules and performance measures, and then used these to compare computer models of alternative future states of the highway network. The models showed whether changing current construction decision practices will produce a better network. Researchers concluded that changing decision rules had little effect as compared to increasing the overall investment level.
Safety Impacts of Street Lighting at Isolated Rural Intersections
Investigators quantified the effectiveness of roadway lighting as a tool for reducing nighttime crashes at isolated rural intersections. Based on positive results, the researchers recommended that MnDOT consider revising its lighting guidelines to apply to a higher percentage of rural intersections, provide quantifiable volume and crash measurements, and consider roadway functional classification.
Putting Research into Practice: Minnesota Seal Coat Handbook 2006
This project updated the extremely popular 1998 handbook and created an accompanying training module in light of recent Mn/DOT seal coating studies, specifications and field experience. The updated handbook covers additional seal coat uses such as fog sealing to rejuvenate pavements and chip sealing on recreational trails.
2006-33 Review of Michigan's Rural Intersection Crashes: Application of Methodology for Identifying Intersections for Intersection Decision Support (IDS)
The objective of the Intersection Decision Support (IDS) research project, sponsored by a consortium of states (Minnesota, California, and Virginia) and the Federal Highway Administration (FHWA), is to improve intersection safety. The Minnesota team's focus is to develop a better understanding of the causes of crashes at rural unsignalized intersections and then develop a technology solution to address the cause(s). In the original study, a review of Minnesota's rural crash records and of past research identified poor driver gap selection as a major contributing cause of rural intersection crashes. Consequently, the design of the rural IDS technology has focused on enhancing the driver's ability to successfully negotiate rural intersections by communicating information about the available gaps in the traffic stream to the driver. In order to develop an IDS technology that has the potential to be nationally deployed, the regional differences at rural intersections must first be understood. Only then can a universal solution be designed and evaluated. To achieve this goal of national consensus and deployment, the University of Minnesota and the Minnesota Department of Transportation initiated a State Pooled Fund study, in which nine states are cooperating in intersection-crash research. This report documents the crash analysis phase of the pooled fund study for the State of Michigan, culminating in a recommendation of an intersection for instrumentation. The driver gap acceptance behavior data to be collected at the selected intersection will feed into the Cooperative Intersection Collision Avoidance System (CICAS) Stop Sign Assist Program.
2006-32 Review of North Carolina's Rural Intersection Crashes: Application of Methodology for Identifying Intersections for Intersection Decision Support
The objective of the Intersection Decision Support (IDS) research project, sponsored by a consortium of states (Minnesota, California, and Virginia) and the Federal Highway Administration (FHWA), is to improve intersection safety. The Minnesota team's focus is to develop a better understanding of the causes of crashes at rural unsignalized intersections and then develop a technology solution to address the cause(s). In the original study, a review of Minnesota's rural crash records and of past research identified poor driver gap selection as a major contributing cause of rural intersection crashes. Consequently, the design of the rural IDS technology has focused on enhancing the driver's ability to successfully negotiate rural intersections by communicating information about the available gaps in the traffic stream to the driver. In order to develop an IDS technology that has the potential to be nationally deployed, the regional differences at rural intersections must first be understood. Only then can a universal solution be designed and evaluated. To achieve this goal of national consensus and deployment, the University of Minnesota and the Minnesota Department of Transportation initiated a State Pooled Fund study, in which nine states are cooperating in intersection-crash research. This report documents the crash analysis phase of the pooled fund study for the State of North Carolina, culminating in a recommendation of an intersection for instrumentation. The driver gap acceptance behavior data to be collected at the selected intersection will feed into the Cooperative Intersection Collision Avoidance System (CICAS) Stop Sign Assist Program.
2006-31 Putting Research into Practice: Field Handbook for Concrete Repair for Local Streets and County Roads
Investigators drew on county expertise and MnDOT specifications to create a streamlined field handbook and accompanying training that present standard plates and step-by-step design and construction guidance for use on low-volume concrete roads, sidewalks, and curbs and gutters.
2006-30 Feasibility Study of Portable Weight-in-Motion Systems for Highway Speed
Minnesota Department of Transportation (Mn/DOT) needs improved traffic monitoring tools to optimally allocate road maintenance and improvement resources. In particular, the department needs a method of including vehicle and axle weights with portable traffic logging equipment. The cost of existing Weigh-in-Motion (WIM) equipment prevents widespread use in locations where only temporary monitoring is needed. This project was a survey of the suppliers of portable WIM systems, allowing a few systems to be moved between locations of interest. There were four candidate systems found and studied, of which two are recommended for further evaluation. Both systems appear to meet the needs Mn/DOT established and local testing will allow a final decision on their suitability.
2006-29 Improving the Ability of Drivers to Avoid Collisions With Snowplows in Fog and Snow
The goal of this work is to understand how the processing of motion under the conditions created by blowing snow causes drivers to fail to detect that they are approaching a vehicle ahead. Color was examined under blowing snow conditions to assess whether an equiluminant (equal brightness) situation was created. In this situation, contrast in light level is not detected but differences in color are. When an equilument situation is created by snow, a perceptual illusion lowers the ability to perceive approach. The results indicate that colors in the red-yellow part of the spectrum can create a dangerous equiluminant situation in blowing snow and fog. We were unable to find an optimum color to paint snowplows to make them less susceptible to rear-end collisions. Perception studies investigated the ability of the visual system to detect the expansion pattern that drivers use to perceive that they are approaching a vehicle. We found that low contrast created by a snow cloud greatly reduces the ability to perceive approach. Flashing lights that increase conspicuity, substantially decreased the chances that a driver will be able to avoid a crash. Additional ways to improve the placement of warning lights based on these findings were proposed.
2006-28 Chemical Inventory and Database Development for Recycled Material Substitutes
Mn/DOT engineers are increasingly looking to recycled materials as readily available and cost-effective substitutes for natural aggregate and to fly ash as a material that can be used in the stabilization of sub-base soils. These recycled wastes have the potenial to contain unacceptably high levels of some chemicals. This project produced chemical data on wastes, non-surface background soils, and natural aggregates for use in a due diligence screening tool in current service by Mn/DOT and developed by the Office of Environmental Services (OES). These data will be used by OES for their internal Mn/DOT due diligence determinations using their streamlined hazard evaluation process. A future Local Road Research Board project will transform the OES streamlined hazard evaluation process into a CD-based product for use by the larger transportation community. Data developed by this current project will be used to populate the future CD-based product electronic database. This project will maintain consistency with the current in use Office of Environmental Services (OES) streamlined hazard evaluation process for waste recycling in Mn/DOT infrastructure projects.
2006-27 Erosion Risk Assessment Tool For Construction Sites
The impact of erosion and sediment from construction sites can be reduced by using a variety of onsite and offsite practices. The WATER model was developed to be a tool to assess the effectiveness of different sediment control practices. The WATER model evaluates risk by performing many simulations of a construction site response for different weather conditions. A particularly important component of the WATER model is the prediction of daily climate variables and storm characteristics called WINDS. This model uses the statistics for the analyzed data to predict many years of possible weather conditions. Predicted weather and storm characteristics are in very good agreement with those observed. The WATER model simulates surface runoff, plant processes, and erosion and sediment transport as major hillslope processes. Four runoff events (spring dry run, spring wet run, fall dry run, and fall wet run) from artificial rainfall conditions were measured.
2006-26 Moisture Effects on PVD and DCP Measurements
This study deals with the experimental investigation of the effects of moisture and density on the elastic moduli and strength of four subgrade soils generally representing the range of road conditions in Minnesota. The testing approach involved i) reduced-scale simulation of field compaction, ii) field-type testing on prismatic soil volumes, and iii) element testing on cylindrical soil specimens. The field-type testing included: i) the GeoGauge, ii) the PRIMA 100 device, iii) the modified light weight deflectometer (LWD) device, iv) the portable vibratory deflectometer (PVD) and v) the Dynamic Cone Penetrometer (DCP). To compare the Young's modulus values stemming from the field-type and laboratory experiments, cylindrical specimens were extracted from the prismatic soil volumes and tested for the resilient modulus (Mr), small-strain Young's modulus using bender elements. The results reveal that both moisture and density have a measurable effect on the elastic modulus and strength of all four soils. On the element testing side, the small strain estimates from the bender element tests were in good agreement with the resilient modulus values. In the context of field testing, there was significant scatter of the estimated Young's moduli depending upon the particular testing device.
2006-25 Improving Road Safety with Two-Way Left-Turn Lanes
Researchers examined the effect on safety and operations of converting traditional four-lane roadways to three-lane roadways with two-way left-turn lanes by analyzing before and after data from nine Minnesota sites. They found that such conversions can improve safety with little impact on operational conditions.
2006-24 Putting Research into Practice: Managing Conflicts Arising from Public Involvement in Transportation Projects
Investigators conducted interviews to refine a previously established system for categorizing and addressing conflicts with the public that arise during transportation projects. They then created a document to implement this system for use in the new version of Mn/DOT's public involvement manual.
2006-23 Urbanization of Minnesota's Countryside, 2000-2025: Evolving Geographies and Transporation Impacts
In this study, we examine population and housing change, changes in industrial activity and occupational changes, and characteristics of commuters and the journey to work for those working away from home in 26 regional centers and their commute sheds in Greater Minnesota. We also explore ways in which Public Use Microdata Samples (PUMS) and Public Use Microdata Areas (PUMAs) might be exploited to shed additional insight into the changing nature of the demographic, economic and commuting patterns that are now pervasive throughout Greater Minnesota. These data are evaluated to explore links between demographic and economic features of working-age populations, and relationships between worker and household characteristics and aspects of commuting activity on the other. The final chapter examines regional economic vitality and travel behavior across the Minnesota Countryside. When population change in sample regional centers in the 1990s is compared with change in the nearby counties that comprise the centers' commuting fields, four situations appear: those where centers and their commuting fields both had population increases; centers with declining populations, but increases in the commuting fields; centers with growing populations, but with declines in their commuting fields; and situations where both the center and the commute field lost population.
2006-22 Development of Efficient Integrated Data Archival/Retrieval Model for R/WIS, RTMS, and Loop Traffic Data
This report describes a new data warehouse model developed for integrating Road Weather Information System (R/WIS) and traffic data and the prototype implemented. The building blocks of the prototype include data aggregation methods from sensors, a data archiving system, and multi-user data access and retrieval environments through a network. This new data warehouse model seamlessly integrates the heterogeneous nature of R/WIS and traffic data. The key to this data model was utilization of a network storage model referred to as a parallel First-In-First-Out (FIFO) data storage where various sensor data are deposited as they are aggregated while different types of data-consuming modules obtain data without an explicit protocol requirement. For the prototype implementation, four different data aggregation methods from traffic and R/WIS sources were used to demonstrate that diverse data types and collection methods could be seamlessly integrated together. As an application of this data warehouse, weather impact on traffic flow was studied by retrieving traffic data under various atmospheric and pavement conditions, and the results are included. It was noticed that R/WIS provides a significant advantage over the traditional National Weather Service data in learning detailed location specific weather and pavement conditions from which weather impact on traffic flow could be accurately analyzed.
2006-21 Contraflow Transportation Network Reconfiguration for Evacuation Route Planning
Given a transportation network having source nodes with evacuees and destination nodes, we want to find a contraflow network configuration, i.e., ideal direction for each edge, to minimize evacuation time. Contraflow is considered a potential remedy to reduce congestion during evacuations in the context of homeland security and natural disasters (e.g., hurricanes). This problem is computationally challenging because of the very large search space and the expensive calculation of evacuation time on a given network. To our knowledge, this paper presents the first macroscopic approaches for the solution of contraflow network reconfiguration incorporating road capacity constraints, multiple sources, congestion factor, and scalability. We formally define the contraflow problem based on graph theory and provide a framework of computational structure to classify our approaches. A Greedy heuristic is designed to produce high quality solutions with significant performance. A Bottleneck Relief heuristic is developed to deal with large numbers of evacuees. We evaluate the proposed approaches both analytically and experimentally using real world datasets. Experimental results show that our contraflow approaches can reduce evacuation time by 40% or more.
2006-20 Validation of DCP and LWD Moisture Specifications for Granular Materials
Advances in technology have produced a new generation of in situ soil testing devices. Implementation of quality assurance procedures that make use of these devices would improve test precision, increase inspector efficiency and safety, and allow for the direct verification of values used in mechanistic design procedures. During this study, the dynamic cone penetrometer (DCP) and light weight deflectometer (LWD) were used on laboratory prepared specimens. It was found that the Mn/DOT DCP specification accurately assessed compaction quality, although there were some suggestions for improvement. This study reached the following conclusions and recommendations. The DCP penetration should continue until the cone passes through the subbase lift of interest. The DCP seating requirement serves little purpose for a subbase lift that will be covered by subsequent lifts. The acceptable range of moisture contents during DCP testing of granular subbase should be capped at 10%. A sufficient amount of data exists to create an LWD trial specification for granular subbase. A mass of 10 kg, drop height of 50 cm, and plate diameter of 20 cm are recommended. It is also recommended that the LWD specification include three seating drops followed by three data drops at each new height.
Full Report: 2006-19
Much of the benefit of an underbody scraper lies in the ability to apply high levels of pressure to break up compacted ice and snow. However, this also leads to increased wear on the underbody's cutting edges and frequent replacement. This process is time and labor intensive and can often lead to a wide variety of injuries. Accordingly, the Quick Edge Rapid Underbody Cutting Edge Changing System was designed to simplify this difficult process and remove some of the risk involved. This report outlines the steps taken in creating the final working design and prototype.
2006-18 Construction Report for MnROAD Thin Whitetopping Test Cells 60-63
After seven years of heavy traffic and weathering, three ultra-thin whitetopping test cells on the interstate portion of the Minnesota Road Research project (MnROAD) had reached terminal serviceability. Those three test cells were replaced by four new thin-whitetopping test cells in October 2004. This report describes the physical characteristics of the new whitetopping test cells 60-63. The report also summarizes the results from the material tests and curl and warp measurements taken during, and immediately following, construction of the test cells.
2006-17 Local Road Tax Options: Is Minnesota Really That Different?
Local governments in the U.S. use a variety of tax mechanisms to fund local roads. Twelve options are examined in this report related to property access, vehicle use or local economic activity. The most frequent local levies are property taxes, special assessments, vehicle registration taxes, motor fuel taxes and local sales taxes. The overall mix of local road funding also varies widely by state and region. Nebraska, Wisconsin and Kansas have local road revenues most like Minnesota, while local roads funding in New Hampshire, Florida and Nevada is the least similar. The benefits of any individual road tax must be judged in the context of the larger state and local tax system.
2006-16 Access to Destinations: Development of Accessibility Measures
Transportation systems are designed to help people participate in activities distributed over space and time. Accessibility indicates the collective performance of land use and transportation systems and determines how well that complex system serves its residents. This research project comprises three main tasks. The first task reviews the literature on accessibility and its performance measures with an emphasis on measures that planners and decision makers can understand and replicate. The second task identifies the appropriate measures of accessibility, where accessibility measures are evaluated in terms of ease of understanding, accuracy and complexity, while the third task illustrates these accessibility measures. During this process a new accessibility measure named Place Rank is introduced as an accurate measure of accessibility. In addition, several previously-defined accessibility measures are reviewed and demonstrated in this report including Cumulative opportunity and gravity-based measures. The gravity-based measure is widely used in the literature yet cumulative opportunity tends to be easier to understand and interpret by the public, planners, and administrators. A major contribution of this research is the comparison of accessibility measures over time and among various modes. Effects of accessibility on home sales are also tested. Homebuyers pay a premium to live near jobs and away from competing workers. Accessibility promises to be a useful tool for monitoring the land use and transportation system, and assessing and valuing the benefits of proposed changes to either land use or networks.
2006-15 Investigation of the Low-Temperature Fracture Properties of Three MnROAD Asphalt Mixtures
In this research effort, field cores were taken from cells 33, 34 and 35 at the MnROAD facility to determine the fracture properties of the field mixtures, to compare them with the laboratory-prepared mixtures analyzed in a previous study, and to evaluate the effect of aging at different depths in the asphalt layer. In addition, the properties of the recovered binders from the field cores as well as the properties of the original binders aged in laboratory conditions were investigated. The test results and the analyses performed indicate that the fracture tests performed on asphalt binders and asphalt mixtures have the potential to predict the field performance of asphalt pavements with respect to thermal cracking. The binder results confirm the predictions of the current performance grading system; however, it appears that the fracture resistance of the PG-34 asphalt mixture is better than the fracture resistance of the PG-40 mixtures, which is the opposite of what the PG system predicts.
2006-14 Streamlining of the Traffic Modeling Process for Implementation in the Twin Cities Freeway Network - Phase II
Comprehensive methodologies are proposed for improving the quality of both freeway and arterial intersections traffic volumes for the purpose of enabling and improving traffic simulations. Specifically, established and enhanced procedures for checking and correcting freeway temporal errors are integrated with an optimization-based algorithm for reconciling spatial inconsistencies in freeway traffic counts. In addition to this, an empirical methodology is further integrated to balance arterial intersection traffic counts. The proposed methodologies have been successfully automated and implemented as two computer programs, i.e., TradaX for processing freeway volume and ArtBaT for arterial intersection traffic counts. Initial evaluations of these tools suggest that they have the potential of reducing total modeling time by 25% ~ 30%, while resulting in improved calibration of simulation models, more reliable analysis, and better use of staff resources for meeting project deadlines.
2006-13 Intelligent Compaction and In-Situ Testing at Mn/DOT TH53
This report describes an intelligent compaction demonstration project on Mn/DOT TH 53 in Duluth, MN, and the associated field and laboratory testing. The project was conducted during September 2005, using a Caterpillar Model CS-563E vibratory soil compactor, equipped with Intelligent Compaction (both Compaction Meter Value (CMV) and energy or power) and global positioning system (GPS) technology. A Prima light-weight deflectometer (LWD), dynamic cone penetrometer (DCP) and Humboldt GeoGauge were used to collect in situ companion test data at 42 locations. Mn/DOT conducted gradation, moisture content and Procter tests. Location and Compaction Meter Value (CMV) were downloaded for comparison with the in situ testing. CMV data was compared to the in situ data on a point-by-point basis and on the basis of the overall distribution. In general, poor correlations were obtained on a point-by-point basis, likely due to the depth and stress dependency of soil modulus, and the heterogeneity of the soils. Good correlations were obtained between CMV values and DCP measurements for depths between 8-inches and 16-inches deep. The Caterpillar Compaction Viewer software, although still in development at the time of testing, is functional and is well integrated with GPS. It is easy to extract data and do more sophisticated analyses. Surface-covering documentation adds value by identifying potential problem areas where compaction is limited by material, moisture or subgrade deficiencies. LWD testing protocol must be followed to obtain useful results, since measurements vary significantly between successive tests. Relatively good correlations were obtained between LWD and GeoGauge. The GPS technology used for the demonstration is not adequate to distinguish between lifts.
2006-12 Duration of Spring-Thaw Recovery for Aggregate-Surfaced Roads
Low-volume roads constructed in regions susceptible to freezing and thawing periods are often at risk of load-related damage during the spring-thaw period. The reduced support capacity during the thawing period is a result of excess melt water that becomes trapped above the underlying frozen layers. Many agencies place spring load restrictions (SLR) during the thaw period to reduce unnecessary damage to the roadways. The period of SLR set forth by the Minnesota Department of Transportation is effective for all flexible pavements; however, experience suggests that many aggregate-surfaced roads require additional time relative to flexible pavements to recover strength sufficient to carry unrestricted loads. An investigation was performed to improve local agencies' ability to evaluate the duration of SLR on aggregate-surfaced roadways. This was accomplished through seasonal measurements of in-situ shear strengths, measured using the dynamic cone penetrometer (DCP), on various Minnesota county routes. In-situ strength tests were conducted on selected county gravel roads over the course of three years. Strength levels recorded during the spring-thaw weakened period were compared to fully recovered periods that typically occur in late spring/summer. The results indicate that aggregate-surfaced roads generally require 1 to 3 additional weeks, over that of flexible pavements, to reach recovered bearing capacity. Additionally, a strong correlation was found between duration required to attain given strength recovery values and climatic and grading inputs.
2006-10 Review of Wisconsin's Rural Intersection Crashes: Application of Methodology for Indentifying Intersections for Intersection Decision Support (IDS)
The Intersection Decision Support (IDS) research project is sponsored by a consortium of states (Minnesota, California, and Virginia) and the Federal Highway Administration (FHWA) whose objective is to improve intersection safety. The Minnesota team's focus is to develop a better understanding of the causes of crashes at rural unsignalized intersections and then develop a technology solution to address the cause(s). In the original study, a review of Minnesota's rural crash records and of past research identified poor driver gap selection as a major contributing cause of rural intersection crashes. Consequently, the design of the rural IDS technology has focused on enhancing the driver's ability to successfully negotiate rural intersections by communicating information about the available gaps in the traffic stream to the driver. In order to develop an IDS technology that has the potential to be nationally deployed, the regional differences at rural intersections must first be understood. Only then can a universal solution be designed and evaluated. To achieve this goal of national consensus and deployment, the University of Minnesota and the Minnesota Department of Transportation initiated a State Pooled Fund study, in which nine states are cooperating in intersection-crash research. This report documents the crash analysis phase of the pooled fund study for the State of Wisconsin.
2006-09 Performance Effectiveness of Design-Build, Lane Rental, and A + B Contracting Techniques
Experimentation with innovative contracting methods over the last several years has produced several techniques recently formally approved for use by the Federal Highway Administration. While the FHWA has recognized and defined many standard practices for innovative contracting, the need has arisen to compare the effectiveness of different innovative contracting methods to each other. Performance and cost and value implications of A+B contracts, design-build contracts, lane rental contracts, and traditional contracts were investigated. Specific performance and cost measures considered are Administration Costs, Project Costs, Management Complexity, Disruption to Third Parties, RUC, Innovation, Product/Process Quality, and Funding Flexibility. Performance parameters are compared on nine different project types; the methodology utilized a survey of national experts who rated each innovative contracting method for each performance factor on each of the project types. This study resulted in fifteen recommendations for improving management practices in the use of innovative contracting for transportation projects. These recommendations are also intended to assist the Minnesota Department of Transportation in determining which contract method is likely to be most effective given certain project criteria and construction options and to determine directions for future research, particularly on emerging methods such as design-sequencing and A + B + C contracting.
2006-08 North/West Passage Transportation Pooled Fund Program - Phase I
The North/West Passage Transportation Pooled Fund (TPF) Program is a multi-state cooperative program for the coordination, development, and deployment of Intelligent Transportation Systems projects along I-90 and I-94 from the states of Wisconsin to Washington. Individual states along the corridor have developed different systems for collecting, processing and integrating traveler and road maintenance information, and for delivering this information to users. As a result traveler information along the corridor has not been seamless or readily integrated and shared across borders. The objective of this TPF Study Phase I was to influence ongoing standards development; and utilize effective methods for coordinating, integrating, and sharing of traveler information across borders. The Minnesota Department of Transportation (DOT) was the lead agency for this study with North Dakota DOT and Wisconsin DOT also contributing funding for Phase I. A Steering Committee, consisting of members from the eight corridor states (Washington, Idaho, Wyoming, Montana, North Dakota, South Dakota, Minnesota, and Wisconsin), met monthly to coordinate efforts. The Federal Highway Administration served as a monitoring body, providing strategic and technical input. The committee successfully completed eight Phase I corridor projects and approved a Phase II Work Plan focusing on a corridor strategic plan.
2006-07 Fatigue-Resistant Design for Overhead Signs, Mast-Arm Signal Poles, and Lighting Standards
Traffic signs and signals are often supported by flexible cantilevered structures that are susceptible to wind-induced vibration and fatigue. The latest version of the design specifications published by the American Association of State Transportation Officials (AASHTO) now considers fatigue as a limit state. However, most of the fatigue classifications for welded details were not based on full-scale testing, and are thought to be overly conservative. This research will address the fatigue resistance of two common mast arm-to-pole connections used in the state of Minnesota. The resistance attained experimentally aligned with current predictions using AASHTO procedures, except for in-plane loading of box connection details. As a consequence of specimen design, a variety of tube-to-transverse plate connections were also tested using multi-sided tube cross-sections with different tube diameters, tube thicknesses, as well as base plate thicknesses. The standard tube-to-transverse plate connection exhibited Category K2 resistance, two categories lower than the E specified by AASHTO. This resistance was enhanced to Category E through impact treatment or Category E by doubling the base plate thickness. Gusset plates could not prevent cracking of the tube at the base plate, but the tips of the gusset plate exhibited Category E resistance.
2006-06 Blind Deconvolution of Vehicle Inductance Signatures for Travel-Time Estimation
Travel-time data provides vital information for traffic monitoring, management, and planning. The objective of this research was to develop a new computational approach to accurately measure travel time from two sets of spatially separated loop detectors using re-identification of vehicle inductance signatures generated by the loops. In order to restore lost details from the raw inductance waveforms, the author modeled the output of the loop detectors as a convolution of the original vehicle signature and the loop system function. To solve this blind problem, two basic blind deconvolution approaches were used. The first estimates the loop system function using a speed estimate obtained from the inductance waveform. The second approach is an adaptive iterative method referred to as the Godard blind deconvolution. Experimental results showed that both methods performed well and significantly exposed the original signature information with unique vehicle characteristics.
2006-05 A Nonlinear State Space Approach to Arterial Travel Time Prediction
The study uses time series and the Kalman prediction techniques along with modern technology such as the Global Positioning System (GPS) for accurate data collection and analysis. A greater understanding of travel time will help facilitate traffic system performance monitoring, control, planning, and informed route decisions for motorists accessing information from changeable message sings (CMS). The models used for estimations include the autoregressive integrated moving average (ARIMA) and the autoregressive moving average (ARMA). The study collects travel data for the peak hours of travel (3:30-5:00 p.m.) over an eight-month period on the busiest section of Highway 194 in Duluth, Minnesota. The predictions were conducted over two weeks during the summer of 2005. Observed and predicted travel times are charted carefully and report evaluations determine the success of the study.
2006-04 Use of Adhesives to Retrofit Out-of-Plane Distortion Induced Fatigue Cracks
A field test and large-scale test were conducted. Coupon tests revealed reasonable durability when exposed to room temperature, immersion in water at 65 degrees and 111 degrees, air at -4 degrees, repeated freezing and thawing, outdoor elements, and fire. Thorough investigation of the adhesive after application and then again 3 1/2 years after application provides valuable information on how well the adhesive performed in an outdoor environment with intermittent stresses. The report includes organized data showing durability of the product from every application and use throughout the study period, 3 1/2 years. Detailed instructions on field application were developed and are included in this report.
2006-03 Statistical Modeling for Intersection Decision Support
This project was a component of the Intersection Decision Support (IDS) effort conducted at the University of Minnesota. In this project, statistical modeling was applied to crash data from 198 two-way, stop-controlled, intersections on Minnesota rural expressways, in order to: (1) identify intersections that were plausible candidates for future IDS deployment; (2) develop a method for estimating the crash-reduction effect of IDS deployment; (3) develop a method for predicting the crash-reduction potential of IDS deployment, and (4) test the hypothesis that older drivers were over-represented in intersection crashes along US Trunk Highway 52. All these objectives were accomplished using hierarchical model structures similar to that employed in the Interactive Highway Safety Design Model. Five rural expressway intersections were identified as having crash frequencies that were atypically high, and this group included the intersection of US Trunk Highway 52 and Goodhue County highway 9, the site chosen for the prototype IDS deployment. It was then determined that a 3-year count of crashes after deployment would probably be sufficient to detect any crash reduction effect due to the IDS, although a reliable estimate of the magnitude of this effect would require a longer test period. Assuming that the effect of an IDS deployment would be to make the crash frequencies at treated intersections similar to that experienced by typical intersections, it was estimated that deployment of the IDS at the five high-crash intersections would, over a 15-year period, result in a reduction of about 308 crashes. Finally, using an induced-exposure approach, twelve intersections were identified as showing over-representation of older drivers, five of these being on US Trunk Highway 52.
This Bicycle and Pedestrian Toolbox provides transportation planners and engineers with information on how to plan and design a bicycle and pedestrian network for a community. This toolbox summarizes each stage involved in the process of designing an active transportation network with a focus on how land use effects transportation planning. The planning is a cyclical six-stage process where first, community values are determined; second, existing features are evaluated; third, desire lines are identified; fourth, phasing of development is defined; fifth, selecting design treatments; and finally, sixth, evaluation of the network based on performance criteria.
2006-01 Investigation of Deterioration of Stainless Steel Dowel Tubes Under Repeated Loading
The Minnesota Department of Transportation (Mn/DOT) has selected a 316L stainless steel schedule 40 pipe as a new dowel bar to be used as a bid alternative for its high performance Portland Cement Concrete (PCC) pavements. Although this dowel bar should provide sufficient shear transfer capacity and low concrete bearing stresses, there was a concern that lack of a solid core may not provide sufficient resistance of the cross-section to distortion under a heavy axle loading. In this study, long-term performance of the 316L stainless steel schedule 40 pipe was investigated by subjecting a doweled joint to accelerated repeated loads through the use of the Minnesota Accelerated Loading Facility (Minne-ALF-2). Assessment of the new dowel bar performance was performed based on comparison with the standard 1.5 inch diameter epoxy -coated round steel dowel. The following tasks were accomplished: redesign, assembly and calibration of new version of Minne-ALF, development of experimental design matrix, conduct of accelerated full-scale testing, and post-testing evaluation. The results from the MinneALF-2 tests illustrated that while the LTE for the stainless steel dowel tubes was lower than the LTE for the epoxy-coated dowels, the stainless steel tubes are capable of providing over 70% LTE in the long-term when installed in concrete pavement joints. The ability to withstand deformation and corrosion while providing sufficient long-term performance suggests that the stainless steel tube dowel is an attractive alternative to the solid epoxy-coated dowel for use in long-life pavements.
2005- 50 Tools for Predicting Usage and Benefits of Urban Bicycle Network Improvements
This report presents the results of four separate studies regarding the behavior of bicyclists in and around the Twin Cities metropolitan area. The four reports are: - Effect of Trails on Cycling based on a 2000 Travel Behavior Inventory that analyzes behaviors based on the distance of a person's home from the nearest cycling facility. - Value of Bicycle Facilities to Commuters based on a survey asking respondents to choose among commutes of varying durations on bicycle facilities with different characteristics. - Effect of Facilities on Commute Mode Share analyzing the results of the construction of new commuter-oriented bicycling facilities. - Cycling Behavior Near Facilities which seeks to explain the relationship between cycling behaviors and trail access, as well as various demographic and lifestyle factors. In general, the reports support the thesis that people value bicycle facilities and are willing to devote additional time to use higher quality facilities. In particular, riders who use bicycles to commute to work seem to value improvements to striped bike lanes.
2005-49 Impact of Alternative Storm Water Management Approaches on Highway Infrastructure
Investigators conducted a survey and performed inspections to evaluate the performance of various storm water Best Management Practices and whether they negatively impact adjacent roadways. No negative infrastructure effects were discovered.
2005- 48 Evaluation and Improvement of the Stratified Ramp Metering Algorithm Through Microscopic Simulation - Phase II
A new ramp metering strategy implemented on the Twin Cities freeway system to reduce ramp waiting times was evaluated through microsimulation of freeway activity. The study compared Stratified Ramp Metering strategy with the previous Zone Metering Strategy and with no control strategy. Comparison with Zone, which was designed to favor freeway flow, showed the new strategy succeeded in greatly reducing ramp delays and lines. When compared to the results of no control strategy, it reduces freeway travel time, increases freeway speed, smoothes the flow of traffic, and reduces the number of stops. However, travel time, fuel consumption and pollutant emissions are unpredictable under the newer system. Compared to no control strategy, such measures of effectiveness may improve or worsen depending on the freeway patterns and demand. Based on these findings, the researchers will seek improvements to the design of the Stratified Ramp Metering algorithm so as to factor in disruptive traffic patterns.
2005- 47 Load Testing of Instrumented Pavement Sections
This report summarizes and references seven previously written reports developed from this project. The objective of this project was to use the field-measured strains from a number of MnROAD cells to develop mechanistically based load equivalency factors (LEF). The load equivalency factors commonly in use were developed from the AASHTO Road Test conducted in the late 1950s at Ottawa, Illinois. The AASHTO-based LEF represented the pavement behavior at the Road Test and might not reflect conditions in other climates, other subgrade soils, pavement sections, traffic and so on. Several of the MnROAD project objectives related to the development of improved mechanistic models and the development of improved pavement design methods. The Load Testing of Instrumented Pavement Sections project included strain measurements from a variety of vehicle loads, including single, tandem, and tridem axles, tire pressures, tire types, various vehicle speeds, and several different seasons. The testing and analysis resulted in the evaluation of various mechanistic models and the selection of WESLEA for flexible pavements and ISLAB2000 for rigid pavements. Many of the strain sensors, installed during construction in 1993 or 1994, no longer worked limiting the number of test cells available and the scope of the study. The LEF analysis for flexible pavements were based on only the tensile strain at the bottom of the asphalt, and were generally lower than the corresponding AASHTO factors. There were too few strain sensors available to conduct an LEF analysis on rigid pavements, however, during the selection of ISLAB2000, a number of relationships were developed that relate k-value, to other factors such as slab thickness, slab elastic modulus, and strain.
2005- 46 Assessment of AFLP-based Genetic Variation in Three Native Plant Species Across the State of Minnesota
Analysis of genetic diversity and population differentiation determines how diverse natural populations are and how closely related they are to one another, which can provide clues concerning adaptation for restoration projects. This research analyzed the genetic diversity of three native species across their range in Minnesota. Using Amplified Fragment Length Polymorphisms, the genetic diversities of three species-prairie cordgrass (Spartina pectinata), purple prairie clover (Dalea purpurea), and spotted Joe-pye weed (Eupatorium maculatum)-were examined. The diversity for all the species had more disjunct relationships rather than displaying geographic or ecological patterns. The genotypic variation may be due to ecotypic variation or to genetic drift as a result of habitat fragmentation. The species had Gst values, a measure of how much populations differ, that ranged from 0.18 up to 0.27, indicating clear population differentiation. Analysis of molecular variance results concurred. The natural populations of all these species showed moderate levels of genetic diversity. This information is helpful in ensuring adequate diversity in seed sources for restorations. Additional research on these populations by performing common garden and reciprocal transplantation experiments would be a useful supplementation to the molecular marker data. For restorations in Minnesota, the best option may be to use seed that is as close as possible.
2005- 45 Forensic Investigation Report for MnROAD Ultra-thin Whitetopping Test Cells 93, 94 and 95
Three instrumented ultra-thin whitetopping (UTW) pavement test sections were constructed in 1997 at the Minnesota Road Research facility (MnROAD). The sections were installed on the interstate highway portion of MnROAD to accelerate the traffic loadings compared to typical applications of UTW. By spring 2004, significant deterioration of the sections had occurred. Prior to replacement of the three test sections in fall 2004, a forensic investigation of the distresses was carried out. The focus of this report was to describe the forensic investigation procedures carried out, and to summarize findings from the investigation. The investigation revealed that the performance of ultra-thin whitetopping test cells at the MnROAD project was related to traffic volume, wheel placement, and layer bonding. Distresses were more frequent and severe in the higher-volume driving lane. Panel sizes that place wheelpaths near the edges of UTW slabs resulted in accelerated distress and poor performance. Bonding of UTW to the underlying asphalt layer was essential for long-term performance. Reflective cracking occurs in bonded concrete overlays for thicknesses less than 5 inches (over 6 inch minimum asphalt layer). Large polyolefin fibers did provide some benefit to crack containment in UTW, but added significant cost to the concrete mix.
2005- 44 The Aurora Consortium - Laboratory and Field Studies of Pavement Temperature Sensors
The Aurora Consortium is a joint program of collaborative research, evaluation and deployment of advanced technologies for detailed road weather monitoring and forecasting. Members seek to implement advanced road and weather information systems that fully integrate state-of-the-art roadway and weather forecasting technologies. Many agencies use various models of in-ground and mobile sensors to measure pavement temperature. However, little documentation exists on the accuracy of the various sensors, and there is no standard methodology for sensor testing. The data and conclusions drawn from this study are published so that Aurora members and others will have additional information to assist in their implementation and procurement decisions. Additionally, results from this study will be used by the NCHRP to develop testing and calibration standards for pavement sensors. The Aurora Consortium is a joint program of collaborative research, evaluation and deployment of advanced technologies for detailed road weather monitoring and forecasting. Members seek to implement advanced road and weather information systems that fully integrate state-of-the-art roadway and weather forecasting technologies. Many agencies use various models of in-ground and mobile sensors to measure pavement temperature. However, little documentation exists on the accuracy of the various sensors, and there is no standard methodology for sensor testing. The data and conclusions drawn from this study are published so that Aurora members and others will have additional information to assist in their implementation and procurement decisions. Additionally, results from this study will be used by the NCHRP to develop testing and calibration standards for pavement sensors. The objective of this project was to conduct both laboratory and field studies of various competing models of in-pavement (contact) and mobile (non-contact) type pavement temperature sensors and compare them to baseline readings in order to quantify the surface temperature measurement performance of each sensor and sensor type. The laboratory tests were conducted at the Braun Intertec laboratory in Bloomington, Minnesota. Field tests were conducted at the Minnesota Department of Transportation's (Mn/DOT's) Mn/ROAD facility near Monticello, Minnesota. The objective of this project was to conduct both laboratory and field studies of various competing models of in-pavement (contact) and mobile (non-contact) type pavement temperature sensors and compare them to baseline readings in order to quantify the surface temperature measurement performance of each sensor and sensor type. The laboratory tests were conducted at the Braun Intertec laboratory in Bloomington, Minnesota. Field tests were conducted at the Minnesota Department of Transportation's (Mn/DOT's) Mn/ROAD facility near Monticello, Minnesota.
With increasing traffic being carried by residential streets, combined with the negative effects of climate on pavement material durability and strength and damage due to frequent cutting and patching of the roadway pavement to allow for the placement of utilities, residential streets are requiring more frequent, extensive, and costly maintenance and rehabilitation (M&R). Also, the pavement design life is significantly reduced. The increased cost of M&R and eventual reconstruction is an added burden on already limited city budgets. To rectify this situation, city managers and engineers are analyzing the difference in cost over a 30 year life-cycle for 9- to 10-ton design standard compared to a 5- to 7-ton design standard. Adopting a more significant pavement structure does, however, have significant cost implications, as the initial cost of the pavement is expected to rise significantly. This increase in cost is expected to be offset by a significant decrease in M&R costs and an increase in pavement life that will delay eventual reconstruction. The Minnesota Department of Transportation (MnDOT), on behalf of the Local Road Research Board (LRRB), initiated this study to evaluate the impact of enhancing roadway construction standards to accommodate greater axle loads on local residential streets in Minnesota cities on life-cycle costs. The primary focus of this study was to compare the current residential roadway construction and maintenance life-cycle costs (5- to 7-ton based on construction standards) to the life-cycle costs of residential roadways constructed with 9- to 10-ton standards.
2005- 42 Identification of Causal Factors and Potential Countermeasures for Fatal Rural Crashes
This project was divided into three phases. In phase 1 ten fatal run-off-road crashes were reconstructed from crash scene diagrams and investigation reports. We found evidence of excessive speed in five of these, and a failure to properly use seatbelts eight of the ten. For seven of these we found that barriers complying with Test Level 3 of NCHRP Report 350 would probably have stopped the crashing vehicle's encroachment. In phase 2 we developed a vehicle trajectory simulation model and used it reconstruct five fatal median-crossing crashes. We found clear evidence of excessive speed in one of these, and in three of the five the encroaching vehicle would probably have been restrained by Test Level 3-compliant barriers. In phase 3 five teams of traffic safety professionals reviewed accident reports from a sample of fatal rural crashes, with the aim of identifying possible causal factors and potential countermeasures. The most frequently identified causal factors were driver inexperience and failure to properly use restraints, while provision of rumble strips, improvements to roadsides or cross-slopes, and provision of guardrails or barriers were the most frequently-cited countermeasures.
2005- 41 Driving Performance During Cell Phone Conversations and Common In-Vehicle Tasks While Sober and Drunk
The crash risk associated with cell phone use while driving is a contentious issue. Many states are introducing Advanced Traveler Information Systems (ATIS) that may be accessed with cell phones while driving (e.g. 511 Traveler Information Services). In these contexts, there is a need for relevant research to determine the risk of cell phone use. This study compared driver performance while conversing on a hands-free cell phone to conditions of operating common in-vehicle controls (e.g., radio, fan, air conditioning) and alcohol intoxication (BAC 0.08). In addition, the study examined the combined effects of being distracted and being intoxicated given that there may be a higher risk of a crash if the driver engages in a combination of risk factors. During simulated traffic scenarios, resource allocation was assessed through behavioral measures and an event-related potential (ERP) novelty oddball paradigm. The results indicated that during a car following scenario, drivers engaged in the conversations or completing in-vehicle tasks were more impaired than drivers that were not involved in any distraction task. Indeed, both the cell phone and in-vehicle sources of distraction were generally more impairing than intoxication at the legal limit. These results will be used in a follow up study in order to compare the effects on attention of driving and using 511 to distraction from these tested distractions.
2005- 40 Development of a Tracking-based Monitoring and Data Collection System
This report outlines a series of vision-based algorithms for data collection at traffic intersections. We have purposed an algorithm for obtaining sound spatial resolution, minimizing occlusions through an optimization-based camera-placement algorithm. A camera calibration algorithm, along with the camera calibration guided user interface tool, is introduced. Finally, a computationally simple data collection system using a multiple cue-based tracker is also presented. Extensive experimental analysis of the system was performed using three different traffic intersections. This report also presents solutions to the problem of reliable target detection and tracking in unconstrained outdoor environments as they pertain to vision-based data collection at traffic intersections.
2005- 39 The Safety and Cost-Effectiveness of Bridge-Approach Guardrail For County State-Aid (CSAH) Bridges in Minnesota
Bridge-approach guardrail provides protection for vehicles from collision with bridge components, such as the blunt end of the bridge rail or abutment, and other types of run-off-the-road collisions. The primary objective of this research was to determine the average daily traffic (ADT) at which the benefit/cost ratio for the installation of approach guardrail at county-state-aid (CSAH) bridges in Minnesota becomes greater than 1.0. A survey of state transportation agencies found that 26 of 35 responding agencies have policies or guidelines requiring placement of approach guardrail on any bridge if the bridge was built using state funds. Results of the research analyses showed that bridge-approach guardrail was effective at reducing the severity of run-off-the-road crashes occurring on the approach or departure to CSAH bridges. Fatalities and A-injury crashes accounted for only 6 percent of the crashes occurring at bridges with approach guardrail compared to 28.5 percent at bridges without approach guardrail. The subsequent benefit/cost analysis showed that bridge-approach guardrail is cost-effective (i.e., B/C > 1) for CSAH bridges with ADT greater than or equal to 300 vehicles per day (vpd). Overall, approach guardrail has a benefit/cost ratio of approximately 3.5 to 5.5. The researchers recommended that the ADT threshold for approach guardrail on CSAH bridges be set at 400 vpd, which is consistent with previous Mn/DOT standards and AASHTO low-volume local road guidelines. Approach guardrail should be considered on a case-by-case basis for bridges with ADT between 150 and 400 vpd, especially those between 300 and 400 vpd. Placement of approach guardrail at bridges with ADT less than 150 vpd is not cost-effective in most cases.
2005-38 Analysis of Girder Differential Deflection and Web Gap Stress for Rapid Assessment of Distortional Fatigue Stress in Multi-Girder Steel Bridges
Distortion-induced fatigue cracking in unstiffened web gaps is common in steel bridges. Previous research by the Minnesota Department of Transportation (Mn/DOT) developed methods to predict the peak web gap stress and maximum differential deflection based upon field data and finite element analyses from two skew supported steel bridges with staggered bent-plate and cross-brace diaphragms, respectively. This project aimed to test the applicability of the proposed methods to a varied spectrum of bridges in the Mn/DOT inventory. An entire bridge model (macro-model) and a model encompassing a portion of the bridge surrounding the diaphragm (micro-model) were calibrated for two instrumented bridges. Dual-level analyses using the macro- and micro-models were performed to account for the uncertainties of boundary conditions. Parameter studies were conducted on the prototypical variations of the bridge models to define the sensitivity of diaphragm stress responses to typical diaphragm and bridge details. Based on these studies, the coefficient in the web gap stress formula was calibrated and a linear prediction of the coefficient was proposed for bridges with different span lengths. Additionally, the prediction of differential deflection was calibrated to include the influence of cross-brace diaphragms, truck loading configurations and additional sidewalk railings. A simple approximation was also proposed for the influence of web gap lateral deflection on web gap stress.
2005-37 Evaluation of Portable Non-Intrusive Traffic Detection System
Traditional traffic data-collection methods, such as inductive loops and road tube counters, require intrusion into the roadway to install. This creates traffic interruptions and safety concerns as personnel are exposed to traffic during installation. This project developed an accurate, simple, cost-effective, portable and safe method of collecting traffic. The Portable Non-Intrusive Traffic Detection System (PNITDS) provides an alternative to conventional methods by allowing agencies to collect data in high-traffic locations without compromising traffic flow or personnel safety. The Minnesota Department of Transportation (Mn/DOT) is the lead state in conducting the PNITDS evaluation test. The project is supported by 16 other participating state DOTs through a pooled-fund effort. The purpose of this project is to provide data-collection practitioners with a cost-effective PNITDS system design. The project fabricated and field-tested a prototype system. This system was then demonstrated to participating pooled fund states for onsite training. The selected design consists of a battery-powered, pole-mounted system that serves as a platform for mounting side-fired non-intrusive traffic sensors. Three sensors were evaluated: the RTMS by EIS, the SAS-1 by SmarTek, and the SmartSensor by Wavetronix. Field-test results were obtained for volume, speed and length-based vehicle classification under a variety of mounting configurations. The project also examined the ease of system setup, system reliability and flexibility. An additional test was conducted to assess a newly developed sensor, The Infra-Red Traffic Logger (TRITL), for its ability to collect axle-based vehicle classification data. Test method and results are included in the project's final report.
2005-36 Enhanced Coordination of Cadastral Information
Any Minnesota Department of Transportation (Mn/DOT) project conducted by Mn/DOT that impacts property owners requires the coordination of cadastral (land ownership) and highway right-of-way information. The timely and accurate identification sharing and coordination of cadastral information is the basis for well-managed highway projects. Mn/DOT has already taken a step towards improving coordination between Mn/DOT offices and other government agencies with the State Parcel Map Inventory (SPMI), a resource with information about the status and accuracy of cadastral information in 87 Minnesota counties. Government agencies have seen the potential in the SPMI to better optimize data development and exchange through the use of GIS technologies. The finding of this project suggest that the SPMI is a starting point for helping coordination, but more targeted efforts are called for. Considering the heterogeneity of local government, individual relationships between organizational staff are crucial to overcoming institutional and technical obstacles.
2005-35 The Financial Benefits of Early Acquisition of Transportation Right of Way
This report addresses the question of whether there are financial benefits to acquiring transportation right of way far in advance of when the improvement will be done. The first part of the analysis is very general, comparing rates of price increase for different types of properties to the opportunity costs of holding land, over a long historical period. The second part of the analysis focuses on Minnesota and examines property price increases by county over shorter, more recent, time periods. While it is almost certainly worthwhile to acquire land that is in danger of becoming developed, this analysis did not find much apparent financial value in early purchase of land that is already developed, or is not likely to become developed. While there could be localized exceptions, prices of these types of land do not in general rise fast enough to offset the opportunity cost of the money that is used to purchase them. However, there could be other, non-financial benefits associated with early purchase that could compensate for some of the costs involved.
2005-34 Best Practices for Project Construction Streamlining
Recent initiatives at the state and federal level have focused attention on possible ways of streamlining or expediting the project delivery process. While some of these efforts have focused on methods and practices to speed planning and pre-construction activities, the purpose of this investigation was to examine means of speeding the roadway and highway construction cycle. Highway construction time has very real costs to all parties involved in the process; highway departments, contractors, and most especially the public whose tax dollars and time is spent waiting for projects to be completed. Recognizing this, the Local Road Research Board's (LRRB) Research Implementation Committee (RIC) began this investigation to explore current activities, techniques and materials whose use reduces construction time, and to determine the extent of their use by city and county engineers in Minnesota.
2005-33 State Aid Concrete Pavement Rehabilitation (CPR) Best Practices Manual
This manual has been designed to be used as specifications for concrete repair of local city streets and county concrete pavements. It is intended to be used as supplemental specifications for constructing this work throughout the state of Minnesota. All standard plates have been designated as SA, which is an abbreviation for State Aid. This is intended to allow the State Aid office to track bid prices with a consistent title throughout the state. This manual was developed from existing concrete repair standards that have been developed and used by the Minnesota Department of Transportation since 1981. This manual also incorporates successful modifications to the Mn/DOT standards by the City of Owatonna and the City of Austin, Mn. This manual keeps the Mn/DOT system of labeling repairs in the A,B,C nomenclature developed in 1981 as follows; SA-A repairs are joint or crack repairs. SA-B repairs are partial depth repairs. SA-C repairs are full depth concrete repairs. For the first time this manual incorporates standards for sidewalk and curb and gutter repairs into a specification format. These sidewalk and curb and gutter standards have been successfully performed by the cities of Austin and Owatonna, Minnesota.
2005-32 Improvement and Validation of Mn/DOT DCP Specifications for Aggregate Base Materials and Select Granular
Eleven construction projects from around the state were selected for testing during the summer of 2003. At each construction project, several locations were randomly selected for testing. At each location, various devices were used to obtain in-situ stiffness, strength, density and moisture data. In addition, samples were also taken for gradation and Proctor tests from the majority of the test locations. The materials included Select Granular, CL3, CL5, CL6, CL7 and full-depth reclamation. The proposed DCP specification from 2002 testing was validated and modified using the 2003 data.
Driver Assistive Systems for Rural Applications: Digital Mapping of Roads for Lane Departure Warnings
Deployment of any system is driven by market demand and system cost. Initial deployment of the Intelligent Vehicle Lab Snowplow Driver Assistive System (DAS) was limited to a 45 mile section of Minnesota Trunk Highway 7 west of I-494 and east of Hutchinson MN. To better gage demand and functionality, St. Louis and Polk Counties in Minnesota operationally tested the system during the winter of 2003-2004; Polk County also tested during the winter of 2004-2005. Operational benefits were found to be drastically different in the two counties. Low visibility was not an issue with the St. Louis County snowplow routes, so the system offered few benefits. In contrast the topology of Polk County is flat, with almost no trees. High winds combined with few visual cues create significant low visibility conditions. Polk County was pleased with their original system, and obtained a second system and tested it operationally during the 2004-2005 Winter. The experience of these two counties is documented in Volume One. A key component of the DAS is a high accuracy digital map. With the exception of the mapping process, the present cost of the DAS is well documented. With cost data complete, counties can determine whether to acquire these systems.
2005-30 Driver Assistive Systems for Rural Applications: A Path to Deployment
Deployment of any system is driven by market demand and system cost. Initial deployment of the Intelligent Vehicle Lab Snowplow Driver Assistive System (DAS) was limited to a 45 mile section of Minnesota Trunk Highway 7 west of I-494 and east of Hutchinson MN. To better gage demand and functionality, St. Louis and Polk Counties in Minnesota operationally tested the system during the winter of 2003-2004; Polk County also tested during the winter of 2004-2005. Operational benefits were found to be drastically different in the two counties. Low visibility was not an issue with the St. Louis County snowplow routes, so the system offered few benefits. In contrast the topology of Polk county is flat, with almost no trees. High winds combined with few visual cues create significant low visibility conditions. Polk County was pleased with their original system, and obtained a second system and tested it operationally during the 2004-2005 winter. The experience of these two counties is documented in this volume, Volume One. A key component of the DAS is a high accuracy digital map. With the exception of the mapping process, the present cost of the DAS is well documented. Volume Two describes a system designed to collect and process geospatial data to be used by driver assitive system, and the costs and time associated with collecting map data, and creating a map from that data. With cost data complete, counties can determine whether to acquire these systems.
2005-29 Test and Validation of a Model for Forecasting Frost on Bridges
Frost on roadways and bridges can present hazardous conditions, especially when it occurs where adjacent roadways are clear of frost. Most frost warnings depend solely on accurate prediction of bridge surface temperature and ambient atmospheric conditions -- all routinely calculated by traditional weather forecast models. This project examined the effectiveness of BridgeT, a finite difference program that predicts bridge surface temperature by simulating vertical heat transfer in a bridge in response to evolving weather conditions produced by a forecast model. Results show that BridgeT realistically represents early-morning low temperatures and temperature trends when run with input from observations of air temperature, wind speed and radiation.
The development of small bumps in the surface of hot-mix asphalt overlays has been a problem for state and local highway agencies for many years. Sometimes these bumps are small and are not large enough to be felt by drivers. Under many conditions, however, they can be large enough to cause ride-related problems at normal operating speeds. Under this project, a survey was conducted of local and state engineers in Minnesota responsible for highway construction and maintenance to compile corrective actions that they have used avoid these bumps and to mitigate their effects if they occur. Instrumentation sites were incorporated into this project to determine the magnitudes and profiles of temperature in the existing asphalt layer when a new layer of hot asphalt is placed on top of it. The instrumentation sites were also used to gain further information on the common practices of highway construction personnel in reducing the probability of bumps, and mitigation efforts if bumps occur. This report describes the survey, site visits, construction instrumentation, laboratory studies, and evaluation conducted by the project team. It also presents a draft booklet compiling the common practices for avoiding and mitigating bumps gathered throughout the project.
2005-27 Synthesis of Current Minnesota Practices of Thin and Ultra-Thin Whitetopping
This report documents the current practices of Minesota in rehabiliting Hot Mix Asphat pavement with thin and ultra-thin Portland cement concrete overleys, i.e. thin and ultra-thin whitetopping. The current practices of thin whitetopping (TWT) in Minnesota and its adjacent states have shown that TWT has been used successfully and is an important alternative for rehabilitating HMA pavements of medium volume roads. If designed and constructed properly, TWT is also an important alternative for rehabilitating HMA pavements of highway volume roads with more requirements in HMA quality, bonding and fiber reinforcement. The performance of ultra-thin whitetopping (UTW) projects in Minnesota ranges from very good to failing. The sections that perform poorly are short sections under stopping trucks or buses and over thin or poor condition HMA pavement. UTW has been used successfully in Minnesota when inlaid into thick and sound HMA pavements even in high-volume traffic. The quality of the HMA substrate, bonding, fiber reinforcement, and joint spacing all significantly affect the success of UTW. The great caution should be used when rehabilitating HMA pavements at bus stops, weigh stations, and intersections. The Minnesota Department of Transportation (Mn/DOT) does not recommend UTW for major highways and heavy traffic areas.
2005-25 Preliminary Laboratory Investigation of Enzyme Solutions as a Soil Stabilizer
This research studied the effect of two enzymes as soil stabilizers on two soil types to determine how and under what conditions they function. Researchers evaluated the chemical composition, mode of action, resilient modulus, and shear strength to determine the effects of the enzymes A and B on the soils I and II. The enzymes produced a high concentration of protein and observations suggest the enzymes behave like a surfactant, which effects its stabilization performance. The specimens were subjected to testing of varying lengths of time to determine their performance. Researchers observed an increase in the resilient modulus as the curing time increased but that an increase in application rate, as suggested by manufacturers, did not improve the performance of the enzymes. The study also suggests noticeable differences between the two enzymes and their effects on the soils in terms of resilient modulus and the stiffness of the soil.
2005-24 User Perspectives on Location Efficient Mortgages & Car Sharing
A burgeoning population seeking relatively affordable housing is placing high demands on outlying, auto-dependent residential markets. Simultaneously, public policies addressing housing, transportation, and land use aim to increase homeownership, decrease drive-alone travel, and harness outlying development. A relatively new mortgage lending procedure aims to address each of these public policy aims synergistically by allowing low- and moderate-income households the opportunity to purchase homes in transit-accessible neighborhoods that would otherwise be unobtainable because of cost. The goal of this research is to evaluate this initiative, as well as position it within the broader goals of smart growth, describe its application, and comment on its prospects. This report constitutes a primer of the current state of knowledge about these unique loan programs.
2005-23 The Cost and Effectiveness of Stormwater Management Practices
Stormwater management practices for treating urban rainwater runoff were evaluated for cost and effectiveness in removing suspended sediments and phosphorus. Construction and annual operating and maintenance cost data was collected and analyzed for dry detention basins, wet basins, sand filters, constructed wetlands, bioretention filters, infiltration trenches, and swales using literature that reported on existing SMP sites across the United States. After statistical analysis on historical values of inflation and bond yields, the annual operating and maintenance costs were converted to a present worth based on a 20-year life and added to the construction cost. The total present cost of each SMP with the 67% confidence interval was reported as a function of the water quality design volume or, in the case of swales as a function of the swale top width, again with a 67% confidence interval. Finally, the mass of total suspended solids and total phosphorus removed over the 20-year life was estimated as a function of the water quality volume. The results can be used by planners and designers to estimate both the total cost of installing a stormwater management practice at a given site and the corresponding total suspended solids and phosphorus removal.
Performance of Thermoplastic Pipe Under Highway Vehicle Loading
The report presents the literature relating to design of thermoplastic pipe, describes the development and implementation of field tests conducted for this project, extends the findings of the field tests through calibration of two- and three-dimensional computer models and parametric studies, and makes recommendations for design and installation of thermoplastic pipe under shallow cover and highway live loads.
The purpose of this project, Trucks and Twin Cities Traffic Management, is to identify strategies that will reduce congestion for trucks traveling within and through the Twin Cities. The planning and development of most highway facilities focuses on the general needs of the majority of traffic in the traffic stream. However, the performance, function, and purpose of heavy trucks are dissimilar to those of the majority of the vehicles in the traffic stream. It is for this reason that the National Cooperative Highway Research synthesis report 314 identified a number of improvements that state transportation agencies have implemented, or are planning to implement, that focus on the unique needs of trucks to better accommodate truck-borne freight traffic. Additionally, to help reduce delays and congestion a number of urban areas have conducted studies of the unique issues trucks face.
2005-20 Route Preferences and the Value of Travel-Time Information for Motorists Driving Real-World Routes
While there is a sizable body of literature on the benefits of travel information, most of it is based on theory or on simulations. This experiment analyzes results based on a field test of 117 drivers completing the same point-to-point trip in their own vehicles via five different routes. Participants traveled both arterial and freeway routes, assessed the travel information that was provided, evaluated the importance of the accuracy of the information and charted their route preferences for various trip purposes. Researchers were not looking merely for perceived time savings but driver perception of the value of the time saved in order to make projections about whether drivers would be willing to pay for accurate travel updates as a means of reducing overall cost, anxiety and uncertainty while driving. Knowledge of how much users want to pay for Advance Travel Information System (ATIS) services is necessary for the design of sustainable for-profit private services or private/public partnerships.
2005-19 Development of a Web-Based Economic Impact Calculator for Small and Medium Size Airports
This report details the development of a Web-based economic impact calculator for Minnesota's Small and Medium Size, General Aviation airports. In this case, economic impact is defined as the result of expenditures or sales transactions between businesses or other entities that can be directly traced to the presence of an airport. The process involved site visits to 51 airports, meetings with airport managers, Fixed Base Operators (FBO), and Metropolitan council officials, as well as data collection of financials from airport sponsors and FBOs. After testing on the calculator was completed, it was transferred to the Mn/DOT Aeronautics server and can be found at http://dotapp1.dot.state.mn.us:8080/aeic/main.htm. We recommend, however, that a new effort be considered to obtain more detailed financials for FBOs as a way to improve calculator accuracy. Although the current model provides a good estimation of FBO expenditures, greater accuracy could be obtained with more data.
Gang plowing is one method used by the Minnesota Department of Transportation (Mn/DOT) to increase the productivity of snowplow operations. However, these gains in productivity often come at the expense of increased driver stress. These higher stress levels are the result of the low visibility caused by localized snow clouds created by the lead snowplow, and by anxious drivers trying to pass between the moving plows. To improve the gang plowing process, a DGPS-based gang plowing system has been developed. This system uses advanced technology to allow a trailing snowplow to automatically follow a lead snowplow at an operator-specified lateral and longitudinal offset. The system is designed to improve both safety and productivity. This report covers three areas. First, to improve driver visibility, an implementation of the virtual mirror to the left side of the trailing plow is described. Second, the lateral and longitudinal performance of a two-vehicle gang on Minnesota Trunk Highway 101 is described. Third, a system architecture for gangs of more than two vehicles is proposed, and its potential performance is documented through simulation. Finally, recommendations for further research and other potential applications are provided.
2005-17 Telework, Telecommunications and Community Design
2005-16 The Effects of In-Lane Rumble Strips on the Stopping Behavior of Sleep-Deprived Drivers
The authors have designed three studies to investigate the influence of in-lane (transverse) rumble strips on the braking patterns of drivers when the rumble strips are used to warn drivers of an upcoming traffic control device. Prior to these studies, no empirical work existed that could provide accurate confirmation of the effects of rumble strips on braking patterns. Despite their extensive use, in-lane rumble strips are not listed in the Manual of Uniform Traffic Control Devices as an approved traffic control device. This portion of the research involves the use of a simulator to study braking patterns among sleep-deprived drivers who encounter rumble strips upon approaching a stop sign. The 20 subjects were commercial drivers between the ages of 25 and 60 with at least three year's driving experience. Each participant drove the 60-mile test route four times. Driving performance was measured using a battery of tests, including an EyeCheck device, an acuity test, a contrast sensitivity test, a psycho-motor vigilance test and a code substitution test. Results indicate that there was little difference in mean approach speeds to controlled intersections with or without rumble strips. However, the presence of rumble strips caused drivers to brake to a greater extent earlier in the approach. Although sleep deprivation affected the steering patterns of drivers, it did not seem to affect their braking patterns.
2005-15 Cost/Benefit Study of: Spring Load Restrictions
Across the state of Minnesota, asphalt roads under the jurisdiction of counties, cities and townships have been controlled by restrictions that limit the total weight of each truck that uses those roads during the spring thaw period. During this time, the pavement weakens and the bearing capacity of the roadway is reduced. These policies vary from county to county and from road to road, depending on the capacity of the roads--typically, 5, 7 and 9 tons. While spring load restrictions serve to extend the useful life of the road, they also add significant burdens to truckers who are forced to re-route their vehicles and/or increase the number of trips in order to adhere to the policies. This study assesses the economic impact of lifting all vehicle restrictions during the spring thaw period. Economic benefits of lifting the bans include reduced cost to carriers; potential cost includes reduced pavement life. Their research concludes that if the policy is changed, the costs of additional damage could be recovered from those who use the roads. Recovering those costs could take the form of annual fees, appropriate fuel taxes and/or user charges paid by vehicle operators.
Earth pressure cells, tiltmeters, strain gages, inclinometer casings, and survey reflectors were installed in fall 2002 during construction of a 26-ft (7.9-m) high Minnesota Department of Transportation (Mn/DOT) reinforced concrete cantilever retaining wall. A data acquisition system with remote access monitored some 60 sensors on a continual basis. Analyses of the data indicated the development of active earth pressure at the end of backfilling, with a resultant at about one-third of the backfill height. Translation of 0.45 in. (11 mm), or about 0.1% of the backfill height, was responsible for development of the active condition. The wall also rotated 0.03
2005-13 Retrofitting Shear Cracks in Reinforced Concrete Pier Caps Using Carbon Fiber Reinforced Polymers
The Minnesota Department of Transportation (Mn/DOT) documented the appearance of excessive cracks in the reinforced concrete pier cap overhangs of State Highway Bridges 19855 and 19856. As a part of this study, the ultimate capacity of the pier cap overhangs was estimated by comparing predicted capacities calculated using standard design specifications to experimental results published in the worldwide literature. It was determined that the ultimate capacity of the pier cap overhangs was more than sufficient to assure that a cracked, but undeteriorated, pier cap is not prone to structural failure. An estimate of the initial cracking load of the pier cap overhangs was also created to determine what changes to pier cap design would be required to prevent future overhangs from cracking.
2005-12 Project Management Software: Practical Applications for Improved Project Management
Project management software is designed to make the job of a project manager easier and more efficient, providing applications to aid in planning, to manage project costs, and to track activities and monitor schedules. As more and more public works departments face the realities of increasing workloads and shrinking resources, finding technology applications that allow productivity gains becomes ever more important. The use of project management software as a tool for managing and organizing work has grown and continues to grow at a rapid pace in all industries. This paper reviews the ways in which it is currently being used in the course of transportation project delivery in Minnesota, and provides a tool to assist in choosing the right application to meet a local city or county's needs.
2005-11 Partners for Good: A Resource Guide for Partnership Efforts in Minnesota Cities and Counties
Joining forces in a partnership relationship is a way for different entities to come together and, building on their respective strengths and abilities, realize together what they could never have realized separately. Although partnership relationships are typically a profitable means for local governments to explore in implementing projects, they become even more compelling when resources are limited and multiple needs compete for scarce available dollars. This paper explores the use of partnerships in Minnesota to advance needed public works projects. It discusses some of the nuances of what partnerships can mean to local units of government, from the ways in which bartering of services, equipment, and staff expertise allows local units of government to make efficient resource decisions to how major public works projects can be implemented through the concerted efforts of interested partners. Through the use of focus group discussions, selected case studies, and the expertise of the Technical Advisory Panel (TAP) overseeing this effort, a best practices guide to Minnesota city and county partnering efforts results.
2005-10 The Effect of Minnesota Aggregates on Rapid Chloride Permeability Tests
This report investigates the effect of the type of coarse aggregate used in concrete on chloride ions penetrability as indicated by the rapid chloride penetration test (RCPT). Twelve coarse aggregate types, commonly used in Minnesota Department of Transportation highway construction projects, were identified and used for this study. The coarse aggregate types were subjected to laboratory testing to determine their physical properties and ambient chloride content. The aggregate types were used to prepare fresh concrete according to Mn/DOT specifications in which silica fume and fly ash were used. In order to characterize the concrete in terms of resistance to chloride ions penetration, concrete specimens made of these aggregate types were subjected to the rapid chloride permeability test at different ages. All mix parameters including gradation and quantities of different aggregates were held constant in different mixes. The only variable was the aggregate type. For concrete specimens tested at 28 days of age, the average total charge passed varied between 1,452 and 2,606 Coulombs, which can be described as low to moderate chloride ions penetrability, according to AASHTO designation. The average total charge passed decreased with time (age) for all of the concrete specimens tested. Considering specimens at 91 days of age, the average total charge passed ranged from 601 to 1,236 Coulombs, which can be characterized as very low to low chloride ions penetrability. The aggregate type has a noticeable influence on the RCPT results for the concrete mix design that was utilized.
Research into cost comparisons between maintaining gravel surfaces on low-volume roads and paving and maintaining those same roads was conducted by studying the annual reports provided by 25 counties throughout greater Minnesota to the Minnesota Department of Transportation State Aid Office. Researchers also conducted personal interviews with transportation officials in some of these counties. The result is an analytical method for estimating the cost of replacing (and maintaining) a gravel road with a surface paved with hot mix asphalt. Upgrading and maintenance activities that were quantified included maintenance grading, re-graveling, dust control and stabilization, reconstruction and regrading, among others. In examining and projecting costs, the authors conclude that depending on the use of historical cost figures may lead to an underestimation of the actual costs associated with maintenance. They also recommend that transportation officials give serious consideration to upgrading roads that experience an average traffic volume of 200 vehicles per day.
2005-08 Distillate Usage Patterns in Minnesota: Development of Data and Tools To Analyze Policies Affecting Biodiesel Usage
Biodiesel is a renewable fuel derived from vegetable oils or animal fats that can substitute for diesel fuel in engines or fuel oil in furnaces. Biodiesel is produced by the process of transesterification, a simple chemical process that breaks individual triglyceride molecules into three molecules of methyl esters consisting of long chain fatty acids, similar to diesel derived from petroleum. Biodiesel has proven lubricity benefits at low blends, which will be important when sulfur levels are reduced in the U.S. supply of diesel in 2006. In addition, blends of biodiesel and its usage in a pure form reduce particulate matter (PM), volatile organic compounds (VOC), as well as other toxic gases and Greenhouse Gases (GHG). Reduced emissions from biodiesel blends result from its zero sulfur content and higher oxygen content versus petro-diesel. Federal standards established by the U.S. Environmental Protection Agency (EPA) may force local authorities to implement a variety of policies to reduce VOC's, one of the precursors of ground level ozone formation, and other toxic emissions. There is also substantial concern among public health professionals concerning the formation of particulate matter (PM) from diesel engines, especially when originating from school buses, transit buses, and diesel-powered electrical generators.
2005-07 Continuous Compaction Control Demonstration
In September 2004, engineers conducted a Continuous Compaction Control (CCC) demonstration at MnRoad, an outdoor pavement test facility. Continuous Compaction Control (CCC), also called Intelligent Compaction (IC), is a new technique in the United States construction market that uses an instrumented compactor to measure soil or asphalt compaction in real time and adjusts compactive effort accordingly to control the level of compaction. This demonstration used the BOMAG Compactor and focused on Young's soil modulus as the soil parameter of interest. CCC may potentially provide substantial benefits, including improved quality due to more uniform compaction, reduced compaction costs because effort is applied only where necessary, reduced life-cycle cost due to longer pavement life, and a stronger relationship between design and construction. State departments of transportation have expressed interest in exploring this method as a way of meeting quality-assurance requirements within a tight budget environment. In general, this study found CCC to be an effective quality-control mechanism for soil compaction. However, further questions arose as a result of the study and certain variables affected the results and measurements, including moisture content and the use of different measurement tools. Further research is needed to determine the level of uniformity in using CCC and the extent of reliability in achieving target values when using this method.
2005-06 Moisture Retention Characteristics of Base and Sub-base Materials
Soil water retention refers to the relationship between the amount of soil water and the energy with which it is held. This relationship is important for characterizing water movement through granular materials. In this project, we generated soil moisture retention data of 18 non-recycled and 7 recycled materials used in pavement construction. The results showed that water retention of non-recycled materials was nearly similar. The major differences among the curves were in the inflection points (air entry values) and in the water contents either near saturation or at 15,300 cm of suction. Using this database, we also developed Pedo-transfer functions that can predict (1) water retention or (2) the parameters of functions that describe water retention from easily measurable properties of the pavement materials. Water retention of concrete with and without shingles was only slightly different. This is partially because shingle chips imbedded in the concrete were large. Traditionally, the influence of matric suction has not been directly considered in pavement design. The water retention data in this report will be helpful in developing resistance factors for Minnesota Flexible Pavement Design Program either through physical modeling or through statistical relationships between design criteria and the water contents.
2005-05 Impacts of Overweight Implements of Husbandry on Minnesota Roads and Bridges
Over the past few decades, the national industry has seen the number of farms decrease with a simultaneous increase in the average farm size. With larger farms and continuously improving farming techniques, the need to increase production and efficiency has affected equipment carrying capacity and completely changed the tools being used. During select seasons, it is common to have single-axle loads on secondary roads and bridges that exceed normal load limits (typical examples are grain carts and manure wagons). Even though these load levels occur only during a short period of time of the year (fall for grain carts and spring for manure wagons), there is concern that they can do significant damage to pavements and bridges. Currently, the only limitation placed upon farm implements is a metric based upon the load per unit width of tire. This metric does not appear to be consistent with the metrics commonly used during design of infrastructure. The objective of the work presented in this report was to perform a synthesis study related to the impacts of heavy agriculture vehicles on Minnesota pavements and bridges and to identify those impacts. The synthesis and associated analyses were completed using metrics that are consistent with engineering design and evaluation concepts. The conclusion of this study validates the years of close observation of highway and bridge engineers that the heavy agricultural loads can cause potential problems in terms of both safety to the traveling public and added costs to the maintenance of the local system of highway infrastructure.
2005-04 GPS Based Real-Time Tire-Road Friction Coefficient Identification
This project concentrates on the development of real- time tire-road friction coefficient estimation systems for snowplows that can reliably estimate different road surface friction levels and quickly detect abrupt changes in friction coefficient. Two types of systems are developed - a vehicle-based system and a wheel-based system. The vehiclebased friction measurement system utilizes vehicle motion measurements from differential GPS and other on-board vehicle sensors. The wheel-based friction measurement system utilizes a redundant wheel that is mounted at a small angle to the longitudinal axis of the vehicle.
2005-03 Screening Tool for Using Waste Materials in Paving Projects (STUWMPP)
The properties of soft fine grained soils sometimes require enhancement to facilitate road construction and increase long term road durability. One option for roadbed stabilization is to treat the soil with fly ash, which possesses several beneficial engineering properties. However, the concentrations of elements in fly ash may potentially pose an unacceptable risk to human health. The Screening Tool provides straightforward assessments of this hazard. This tool is intended to be used as part of the assessment of due diligence of these risks. The Screening Tool does not give permission for the use of fly ash and the screening tool was not designed to predict the effects on surface waters, which are regulated by the Minnesota Department of Natural Resources (DNR) and Minnesota Pollution Control Agency (MPCA). This computer program provides guidance to users, but users must make sure the proposed project complies with all applicable and relevant rules and regulations that govern use of fly ash. Details of the calculation and further discussion of the importance of site-specific data is included in this document.
2005-02 Recycyled Asphalt Pavement (RAP) Effects on Binder and Mixture Quality
This report looks at how Recycled Asphalt Pavement (RAP) has been used in Minnesota for over 25 years. The most commonly used method is to mill material from an existing pavement and incorporate it into a new asphalt mix. Previous experience and specifications allow various RAP percentages depending on the traffic level. Past research has also shown the effects of RAP on both the high- and low-temperature properties of asphalt cement and the asphalt mixtures. Therefore, it becomes an important priority to study and determine the effects various types and percentages of RAP have on the asphalt cement and mixture quality. This will result in a rational design for asphalt mixture that contain RAP and could change Mn/DOT's asphalt specification.
Minnesota Snow and Ice Control Handbook(2012 Revision)
The purpose of this field handbook is to help promote the understanding of the tools, best practices, and limitations for snow and ice control. The handbook will also help you understand when to use and when not to use these tools and practices. In addition, it encourages progressive changes in snow and ice control practices that will help you reduce salt/sand use and environmental impacts while meeting the safety and mobility needs of roadway users.