Self-compacting concrete offers significant cost benefits in precast girder construction, but performance testing and mix design standards were needed to enable use of SCC in Minnesota. Researchers evaluated wet-state performance of a range of mixes, and cast and instrumented four full-scale girders for laboratory performance testing.
They also cast numerous cylinders to monitor physical characteristics and create performance models. They found SCC to be a suitable construction option.
2008-49 Investigating the Effects on Wildlife of Reed Canarygrass Infestation of Minnesota Wetlands
Habitats that contain reed canarygrass have been found to have lower diversity of traditional native plants, causing researchers to posit that the lower diversity of vegetation resulting from the invasion of reed canarygrass will have a corresponding negative effect on wildlife. While results of this study did not indicate a clear negative impact on wildlife from the invasion of reed canarygrass, researchers did note effects were more evident at lower trophic levels, negatively influencing the plant and invertebrate communities.
2008-48 Improved Methodologies for the Inoculation of Prairie Legumes in Roadside/Revegetation Settings
Researchers have identified that legumes and the level of nitrogen they can contribute are integral to prairie development. MnDOT includes a number of indigenous legumes in its roadside vegetation and wetland restoration plant mixes. Better inoculant delivery systems are needed to ensure that the strains being used are able to persist and function under revegetation conditions. This study recommends the use of granular soil-applied peat inoculant.
2008-47 Corrosion Performance of Epoxy-Coated Reinforcement Bars
High salt levels on the roadways from deicing agents can lead to serious corrosion of uncoated steel reinforcement in bridge decks. Since the 1970s, reinforcing bars have been coated with epoxy to protect them from corrosion. In this study, researchers revisit four bridges that were examined 10 years ago to evaluate the continuing performance and level of corrosion of the epoxy-coated reinforcing bars.
2008-44 Safety Effects of Centerline Rumble Strips in Minnesota
Centerline rumble strips are a safety treatment that is gaining momentum nationally and internationally as an effective, low-cost treatment that can reduce centerline-crossing crashes. This report examines the relationship between centerline rumble strips and traffic safety on rural Minnesota roadways and makes recommendations for centerline rumble strips best practices.
2008-43 Improving Carsharing and Transit Service with ITS
Intelligent Transportation Systems apply technologies to solve surface transportation problems. Two ITS applications—carsharing and Advanced Transportation Information Services—could bring significant benefits to Minnesota residents by providing increased mobility and access to transit services. Researchers surveyed members of HOURCAR, a nonprofit Twin Cities carsharing organization, to gain a better understanding of CSO users in the Twin Cities. Users of Metro Transit's online trip planner were surveyed to assess how their perceptions of trust and confidence in the transit agency were affected by their use of the online trip planning service.
2008-42 Environmental Effects of Deicing Salt on Water Quality in the Twin Cities Metropolitan Area
Using salt to deice roadways in winter plays an important role in providing for the driving safety of Minnesotans. The objective of this research was to learn more about what happens to sodium chloride, the primary chemical used for deicing purposes, after the road salt has completed its job of providing safer winter roadways.
2008-41 Validating Mn/DOT's Precast Composite Slab Span System
Investigators studied the effectiveness of a new design for short-span bridges, monitoring and analyzing bridges in the field and in the laboratory, paying special attention to the development of cracking in the deck above the joints of the bridge.
2008-39 Production and Wind Dispersal of Canada Thistle Seeds
Researchers sought to understand the role that wind dispersal and seed production play in the spread of Canada thistle infestations. They found that wind dispersal is not as significant a factor in Canada thistle seed movement as was commonly thought.
2008-37 Developing and Implementing Enhanced Pavement Marking Mangement Tools: Phase I - Mapping Tool
MnDOT needed an application to support easy online viewing and querying pavement marking data to enable consistent, objective and cost-effective decisions regarding pavement marking needs. Phase I of this multiphase project engaged the Center for Transportation Research and Education at Iowa State University to create a mapping tool to graphically display pavement retroreflectivity data.
2008-36 Generational Perspective on Teen and Older Drivers on Traffic Safety in Rural and Urban Communities
Researchers examined the differences between the experiences and perceptions of high-risk rural and urban drivers—teens and seniors—in connection with driving purpose, crash risk, risk factors associated with crash reduction, and safety interventions. These findings will contribute to the development of effective safety intervention programs targeted to high-risk drivers.
2008-35 Design Tool for Controlling Runoff and Sediment from Highway Construction
Storm water runoff from construction sites can degrade the quality of waters in streams and lakes. To control runoff and create best management practices, developers enhanced a software tool that simulates the impact of highly variable weather conditions on runoff and erosion. The enhanced version factors in both on- and off-site construction variables, and improves modeling capabilities. Additional work is planned to further improve the user interface.
2008-33 The Impact of Bicycling Facilities on Bicycle Commuting Levels
Researchers investigated whether the presence of new bicycle facilities could be correlated with an increase in bicycle commuting rates in various U.S. cities. By mapping facilities constructed in the 1990s and analyzing changes in census data, researchers found no evidence that facilities have a stand-alone effect on bicycle commuting rates. Interviews with city bicycle coordinators revealed the influence of factors including the location of facilities, overall network connectivity and promotion efforts.
2008-32 The Road to a Thoughtful Street Tree Master Plan
Many if not most urban forestry successes and failures begin at the planning stage. The intent of this design manual is to replace as many of the subjective decisions made during street tree design and plant selection with objective criteria. The manual will assist communities and planners to not only select the best trees for their available planting sites, but to use specific principles of street tree design to most effectively create public green spaces, positively affect traffic patterns, and create healthy living spaces. The format of the design manual is one of prompting questions. This will not only help the user select the best plants for the area, but will pose sufficient questions to better ensure that issues of spacing, relative placement to travel corridors, and a wide variety of design elements will be satisfied. The tree species selection philosophy includes not only whether the tree is hardy enough but whether it can achieve the design function for the area. In theory, a well-placed tree in a well-designed landscape will require less maintenance and yield more rewards for the community.
2008-29 LED Emergency Lighting for Snowplows and Other Maintenance Vehicles
Researchers evaluated the safety and effectiveness of equipping MnDOT snowplows with LED-based strobe lights, which are more efficient and cost-effective than standard HID lights. Results showed that while LED lights are as conspicuous as HID for standard driving conditions and viewing angles, they are not as visible when approached from a variety of other viewing angles. Further research is needed to determine whether these angles are relevant to safety.
2008-28 Design Procedure for Bituminous-Stabilized Road Surfaces for Low-Volume Roads
Researchers found that bituminous stabilization of low-volume gravel roads is more cost-effective than maintaining gravel surfaces or upgrading to hot-mix asphalt, creates fewer dust problems, and increases driver safety. Investigators also developed procedures and software to make design choices easier and more reliable than decisions based on empirical estimates.
2008-27 The Effectiveness and Safety of Traffic and Non-Traffic Related Messages Presented on Changeable Message Signs: Phase II
Researchers evaluated how reducing the complexity and ambiguity of CMS messages would affect driver behavior and traffic flow, and learned that clarifying message content could lead to significant improvements in CMS safety and effectiveness.
2008-25 Traffic Volume Thresholds for Requiring Right Turn Lanes and Treatments on Two-Lane Roads
Mn/DOT's right turn lane volume warrants were generally based on qualitative assessment rather than quantitative analysis, resulting in inconsistent application of right turn lanes and an inability to ensure cost-effective intersection design. This research project developed procedures for establishing and applying volume-based warrants that strike a balance between the cost to build a right turn lane or treatment and the money it will save in safety and operational benefits.
2008-24 Determining the Impacts of Roundabouts on Roadway Networks
Roundabouts are gaining in popularity as a method for controlling traffic flow at particular intersections or portions of roadway corridors. They may, however, negatively affect overall system performance. MnDOT developed a toolbox to help cities, counties and other agencies accurately assess the impact of roundabouts on different kinds of highway systems and corridors.
2008-23 Effects of Seasonal Changes on Ride Quality at MnROAD
Investigators found that frost heave, a common problem in winter weather, occurs less frequently and with less severity in thick pavements, in well-draining pavements and in those built over sand subgrades rather than clay subgrades.
2008-22 Putting Research into Practice: Intelligent Compaction Implementation—Research Assessment
This project provided a qualitative assessment of MnDOT's intelligent compaction specifications and procedures, with recommendations for improving IC practices, including the use of lightweight deflectometers for quality assurance, improving equipment calibration techniques and streamlining IC data processing.
2008-21 Designing a Machine for Picking Up Litter Along Minnesota Highways
Collecting trash by hand along highway shoulders and medians in the Twin Cities metropolitan area costs about $2 million per year, is time-consuming and presents serious safety hazards for MnDOT workers. Investigators designed a prototype "trash harvester" for picking up litter in grassy areas. While this prototype did not perform to MnDOT expectations and will not be commercialized at this time, it provides a starting point for further research, design and testing.
2008-20 Putting Research into Practice: Best Practices Handbook for Roadside Vegetation Management 2008
Technical Summary: 200820TS
This project updated the 2000 handbook in light of recent MnDOT studies related to roadside management. The updated handbook includes a new chapter on managing roadside vegetation for wildlife and vehicle safety.
2008-17 Predicting the Cost-Effectiveness of highway Median Barriers
Median barriers are an effective but costly countermeasure for cross median crashes on divided highways. Researchers developed tools MnDOT can use to identify highway sections at high risk for these crashes and predict the costs and benefits of installing cable median barrier on a given highway section.
2008-14 Turn Lane Lengths for Various Speed Roads and Evaluation of Determining Criteria
Researchers developed automated methods for modeling historical and prehistoric surface water features from GIS data already available to enhance the predictive accuracy of Mn/Model, a GIS-based model that predicts the potential of archaeological sites within the state of Minnesota. The research resulted in the development of the ArcGIS Toolbox Historic Water Features Tools, which create a new GIS layer of historic and prehistoric hydrologic features.
Researchers assessed MnDOT's current freight performance measures by identifying more general industry measures, finding available public and private sector freight information sources required for the application of these measures, assessing the cost of using these information sources, and examining the relevance of source data to MnDOT. These measures will aid long-range planning efforts for improving MnDOT's freight transportation system, including the update of the Statewide Transportation Plan.
2008-10 Pavement Evaluation Using Ground Penetrating Radar
This research developed an improved method for using ground penetrating radar data that allows users to determine pavement thickness and the presence of subsurface moisture while driving a GPR van at speeds up to 50 mph, even without having design and construction records about the pavement.
2008-09 Improving Capacity Planning for Demand-Responsive Paratransit Services
Researchers analyzed archived paratransit data to create models and algorithms that can be used to help implement two approaches for improving efficiency: reoptimizing routes and selectively using nondedicated service providers such as taxis. Both measures could provide a cost savings for local transit agencies and service providers.
2008-08 Developing Improved Test Rolling Methods for Roadway Embankment Construction
As part of an effort to improve test rolling equipment and specifications, investigators used models and simulations to study soil-wheel interaction, and conducted field and laboratory tests to develop theories linking wheel sinkage to soil mechanical properties.
2008-07 Effects of Center-Line Rumble Strips on Non-Conventional Vehicles
This research considered the safety impacts of centerline rumble strips on motorcyclist safety and behavior. After reviewing accident data and observing cyclist behavior on the highways and in a closed course, investigators concluded that the strips present no safety hazard to motorcyclists.
2008-06 Decision Tree for Choosing the Optimal Asphalt Pavement Rehabilitation Method
Researchers developed a decision tree for choosing among three common methods of rehabilitating asphalt roads: full depth reclamation, cold-in-place recycling, and mill and overlay. The project report also describes best practices for each of these three rehabilitation techniques.
2008-05 An Inventory of the Public Land Survey Records for Minnesota: The Special Instructions
Investigators located and categorized letters sent to the surveyors who ran public land survey lines and established corner monuments in Minnesota during the 1800s, describing how they should carry out their contracted work. These records, now located in archives in Iowa, Minnesota and Washington, D.C., are of great value to modern surveyors and can be digitally photographed to create a comprehensive Web-based resource.
Researchers studied factors that local engineers believed to cause winter pavement tenting, as well as maintenance strategies for remedying tenting. Based on a literature review, a survey of road engineers in Minnesota and field research, investigators confirmed that deicing chemicals and sands contribute to tenting, and that sealing cracks can reduce its frequency and severity.
2008-02 Evaluation of Paving Fabrics for Isolation of Bituminous Cracking
Makers of pavement fabrics claim that the products can dramatically extend the service lives of overlays without requiring expensive milling and replacing. This study into the impacts of spun-glass paving fabrics in pavement sections scheduled for structural overlays found little performance benefit from these fabrics.
2008-01 Compaction Remediation for Construction Sites
Machinery passing over the right of way during highway construction results in severe soil compaction, which complicates storm water management and requires the purchase of additional land for retaining ponds. Researchers used deep tilling on a variety of soils with different plow types over two growing seasons. Deep tilling proved to be an ROW rehabilitation method.
2008RIC08 Putting Research into Practice: Creating a New Bridge Information Management Tool
Access to bridge data is essential to the effective management of the state's bridges. The Bridge Hydraulic Information database, an interactive, GIS-based application, was launched in late 2002 to allow users to display bridge hydraulic information from Trunk Highway and State Aid structures using a static database of bridge information. The new Bridge Tool, derived from this database, provides authorized users with more data about the state's bridges; displays it on maps; and generates reports from Pontis, the state's bridge management system.
2008RIC06 Putting Research into Practice: Resource for Implementing a Street Sweeping Best Practice
This project synthesized recent street sweeping research to create four information sheets and a PowerPoint presentation about street sweeping best practices. These resources cover street sweeping practices, available technologies and their suitability to local needs.
2008RIC04 Putting Research into Practice: Training Module for Pavement Rehabilitation Selection
This six-hour training workshop leads engineers through the process of determining a pavement rehabilitation approach. Steps include pavement assessment, survey of rehabilitation techniques and decision making.
2008RIC03 Putting Research into Practice: Rural Road Safety Solutions Workshop Materials
This project developed a half-day train-the-trainer workshop and associated educational materials summarizing the latest technologies and techniques most suitable for implementing safety improvements on the local transportation system.