Research Reports

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The Center for Transportation Studies' research reports present the results of University of Minnesota projects in all areas of transportation research.

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    Tank to Wheel Emissions of Ethanol and Biodiesel Powered Vehicles as Compared to Petroleum Alternatives: White Paper
    (Center for Transportation Studies, University of Minnesota, 2010-06) Tessum, Christopher; Marshall, Julian D.; Hill, Jason
    Air quality modeling of the air pollution effects of alternative fuels must be supported with data on the tailpipe emissions of those fuels relative to conventional fuels. Here a literature review is presented of the tailpipe and evaporative emissions from 85% ethanol (E85), 10% ethanol (E10), and 20% biodiesel (BD20) compared to conventional fuels. It is found that E85 causes both positive and negative changes in emissions relative to gasoline, depending on the pollutant, and the changes in some pollutants have an uncertain sign. E10 and BD20 in general exhibit smaller changes in emissions compared to E85, the impacts of which cannot be fully known without air quality modeling.
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    TechPlan: Planning and Policy for Intelligent Transportation Systems
    (State and Local Policy Program, University of Minnesota, 2010) Douma, Frank
    This report covers the most recent work done under the auspices of TechPlan, grants funded through the Intelligent Transportation Systems (ITS) Institute at the University of Minnesota. These grants allow researchers concerned with public policy an opportunity to study how technology affects important decisions about roads, transportation funding, emergency response, and a diverse array of other issues.
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    Implementing a New Forest/Transportation Modeling System in Minnesota
    (Center for Transportation Studies, University of Minnesota, 1993-05-12) Kapple, Douglas C.; Hoganson, Howard M.
    The primary objective of this project was to apply the recently developed forest/transportation modeling system to build a better understanding of transportation related factors influencing the timber supply situation in northern Minnesota. Focus was on both the likely changes in use of the Minnesota road system by the forest products industries and the likely impact of transportation considerations on forest harvesting and wood procurement practices. Of particular interest was the specific wood procurement zones for major Minnesota markets and changes in those zones over time. An important element in addressing these considerations is the dynamic nature of the timber supply situation; even without changes in timber demands, current descriptions of wood shipment patterns may be poor estimates of future patterns as forest conditions can change substantially over time. In simple terms, harvesting generally occurs in the older timber stands and the location of the older stands changes over time. One might expect a cycle in timber transportation costs as low-cost stands close to the market are likely harvested first and will not be available again until regenerated trees are of harvestable age.
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    Development of a Mobile App for Reporting Work Zone Intrusions
    (Minnesota Department of Transportation, 2024-01) Davis, Brian; Morris, Nichole L.; Craig, Curtis; Schumacher, John; Khoday, Annaika
    Work zone intrusions represent a significant safety risk to workers. To help better understand these situations, the Minnesota Department of Transportation partnered with the University of Minnesota to create a method to document intrusion events. This information provides a deeper understanding of the circumstances under which these events occur and enables data-driven decision making when considering ways to reduce or mitigate work zone intrusions. This work focuses on the development of a mobile smartphone app that allows workers to report intrusions from the field immediately after they occur, allowing for timely and accurate intrusion reporting. The work zone intrusion mobile app is developed using an iterative, user-centered design process that solicits feedback from work zone personnel, supervisors, and work zone safety stakeholders at every step in the process. The app uploads completed report data to the existing eSAFE system, allowing for a single repository of collected intrusion report data. To support deployment of the system, training workshops and supporting training and communications materials are created for distribution among users. Throughout the development and deployment of the app, user feedback shows that the app is easy to use and well liked.
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    A Functional Evaluation of Driving Performance for Drivers with Cataracts: Licensing Implications
    (Center for Transportation Studies, University of Minnesota, 1995-12) Wade, Michael; Stackhouse, Stirling P.; Melick, Ann; Tranchida, Donna; Arthur, Erik
    In the design for this study we intended to use three groups of ten subjects: Younger Drivers; Older Drivers who were free of clinically significant cataracts; and drivers with advanced stage Cataracts. Data collection was completed for the first two groups and we collected data on six of the ten cataracts patients. During a greatly protracted delay due to simulator problems, Dr Melick completed her training and moved from Minnesota. We were unable to secure more cataract patients as subjects nor could we obtain the visual function data on the six cataracts patients we had tested in the simulator. This loss of subjects and data greatly reduced the intended scope of this study. This report will be written according to the changed circumstances for this project rather the original intent of the project. The results reported here are based on statistical analyses of the same three groups of subjects but with only six subjects in the Cataract group. The data are restricted to target detection data and driving performance data. Based on this limited analysis we found, as expected, that younger subjects exhibited greater sensitivity in their ability to detect targets than older subjects who in tum were more sensitive than subjects with cataracts. We also found, again as expected, that younger subjects had a greater bias toward stating that a target was present than older subjects who needed slightly less data to state that a target was present than cataract subjects. Our initial hypothesis was that older subjects would need more time to confirm that a target was present than older drivers and that this need for more time would be further extended for subjects with cataracts. This was confirmed. However, we further expected that the increased time needed for target detection by older subjects and by subjects with cataracts would result in less attention being paid to the driving task and therefore, a degradation of driving performance. This prediction was partially confirmed by the data for response time to the onset of simulated brake lights. Older subjects were significantly slower than younger subjects but while cataract subjects were slower than younger subjects, the difference was not significant. Older subjects had slower response times than Cataract subjects but again, this difference was not significant. For both the steering data (keeping the car centered in the lane) as well as for the speed maintenance data there were not significant differences among groups.
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    The Value of Dedicated Right of Way (ROW) to Transit Ridership and Carbon Emissions
    (Center for Transportation Studies, University of Minnesota, 2023-12) Cao, Jason; Tao, Tao; Johnson, Isak; Huang, Hannah
    Transit agencies have adopted various types of right of way (ROW) for transit routes, including mixed traffic, semi-exclusive ROW, exclusive ROW, and grade separation, but few empirical studies have quantified their impacts on ridership and carbon emissions. Using data collected from transit agencies in the US, this research aimed to examine the impacts of dedicated ROW. We applied the gradient boosting decision tree method to estimate the nonlinear relationships between yearly route-level transit ridership and five types of independent variables, with a focus on ROW. The results showed that ROW contributes 18% of the power to predicting transit ridership, which is the largest among all the independent variables. Upgrading from mixed traffic to semi-exclusive ROW could boost ridership by 70,000, on average. A further upgrade to an exclusive ROW could add 3.68 million passengers. Moreover, the number of stops, transit route commence year, population density, signal priority, number of park-and-ride facilities, headway, network density, and route length all have non-trivial contributions to predicting ridership. Upgrading the operating environment could substantially reduce carbon emissions, up to 6.37 million pounds of CO2e. Overall, elevating ROW levels could notably enhance transit ridership and reduce carbon emissions, locating transit routes in the areas with adequate population density and network density could improve their performance, deploying signal priority and improving transit frequency also help, and increasing the share of electric buses could further decrease carbon emissions.
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    Driver Comprehension of Flashing Yellow Arrows
    (Minnesota Department of Transportation, 2023-12) Davis, Gary A.; Stern, Raphael; Duhn, Melissa; Gao, Jingru
    In 2009, the FHWA's Manual on Uniform Traffic Control Devices (MUTCD) introduced the flashing yellow arrow (FYA) traffic signal as an alternative to circular green (CG) to indicate permitted left turns. The FYA is arguably a more intuitive indication that left turns are permitted but not protected and, in addition, the FYA signal heads can support time-of-day changes between protective and permissive left -turn phasing. In 2019, a Research Needs Statement stated that "Research is needed to examine driver comprehension of flashing yellow arrows in different light arrangements and the role of signage." Our objective in this project was to assess drivers' understanding of FYA signal indications and to see if the presence or absence of "Left Turn Yield" signs affect gap acceptance. This was accomplished by conducting an online survey of drivers regarding their understanding of FYA signals and by carrying out a field study of drivers' gap acceptance at a set of Twin Cities intersections.
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    Impacts of Highway and Transitway Construction on Nearby Businesses
    (Center for Transportation Studies, University of Minnesota, 2023-12) Center for Transportation Studies
    This research brief pertains to report CTS 22-02, Commercial Gentrification Along Twin Cities Transitway Corridors (available at and report MnDOT 2023-30, The Effects of Highway Improvement Projects on Nearby Business Activity.
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    Optimizing Asphalt Mixtures for Low-volume Roads in Minnesota
    (Minnesota Department of Transportation, 2023-08) Barman, Manik; Dhasmana, Heena; Manickavasagan, Vishruthi; Marasteanu, Mihai
    Minnesota has a large number of low-volume asphalt roads. These roads typically fail because of environmental factors, such as frigid temperatures, freeze-thaw cycles, and seasonal and daily temperature variations. The goal of this study was to suggest modifications to asphalt mixture designs currently used for low-volume roads in Minnesota to improve the resistance of the mixes against the environmentally driven distresses. The study was conducted by accomplishing multiple tasks, such as a literature review, online survey, fieldwork studying the cause of the asphalt pavement distresses, laboratory work comparing asphalt mixtures designed with Superpave-4, Superpave-5, and regressed air voids methods, and studying the field compaction of Superpave-5 mixes. The mechanical performance of the asphalt mixes was studied by conducting Disc-Shaped Compact Tension (DCT), Indirect Tensile Strength (ITS), and Dynamic Modulus (DM) tests. The study included both laboratory- and plant-produced mixes. The study found that asphalt layers for the low-volume roads did not get enough densification, which augments environmentally driven distresses, such as thermal cracks, and longitudinal joint cracks. The Superpave-5 method holds considerable promise for the design of asphalt mixtures for low-volume roads in Minnesota, which may likely increase the asphalt layer densification and mitigate some of the common distresses.
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    Establishing a Repeatable Method for Presenting Nontraditional Traffic Treatments to Maximize Stakeholder Support
    (Minnesota Department of Transportation, 2023-08) Morris, Nichole L.; Schwieters, Katelyn R.; Craig, Curtis M.; Tian, Disi
    A novel infrastructure design known as the J-turn intersection reduces the risk of serious and fatal crashes at thru-STOP intersections through decreasing points of conflict at an intersection by restricting crossing movements from the minor road. Despite their demonstrated safety efficacy, J-turns have not been met with uniformly positive support. In this research, we first examine novice driver baseline attitudes and driving behaviors on J-turns using a driving simulator study. Results demonstrate that critical errors are decreased with driving exposure to the J-turn; however, attitudes toward J-turns are not improved by exposure alone. A series of studies then evaluates the efficacy of various messaging strategies and educational materials on improving attitudes toward J-turns. The findings from these studies identify that the use of both educational materials and persuasive and customized messaging strategies is an effective method for increasing acceptance of J-turns across diverse resident populations (i.e., rural, suburban, and urban) and among stakeholders in Minnesota. This work demonstrates the importance of the role of proactive educational programs and community initiatives in promoting the acceptance and buy-in toward novel roadway treatments, such as J-turns, among diverse drivers, communities, and stakeholder groups.
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    The Effects of Highway Improvement Projects on Nearby Business Activity
    (Minnesota Department of Transportation, 2023-08) Wexler, Noah; Fan, Yingling
    This report analyzes how state-funded highway improvement projects in the seven county Twin Cities metropolitan area affected businesses in adjacent Census Tracts. We first identify demographic factors associated with the temporal and financial prioritization of some projects over others, finding that the per capita income of a Census Tract is associated with it featuring more heavily prioritized highway improvement construction. We then turn to the effects of highway improvement construction and operation, using results from the previous analysis to account for endogeneity of improvement timing. While we find largely null results of highway improvement on sales, employment, establishment counts, and turnover for both single-establishment and multiple-establishment firms, we also find that pooling data masks several sources of effect heterogeneity. Specifically, we find that single-establishment firms experience negative sales effects from construction when tracts are affected only by infrastructure replacement projects (improvements that do not affect traffic operations, i.e., a bridge replacement). Furthermore, negative sales and employment effects occur after construction is completed for single-establishment firms in urban areas and in tracts affected by longer bouts of construction. Meanwhile, in suburban areas, some modest gains accrue to multiple-establishment firms. These results suggest that regional planners need to account for potential externalities from highway construction on particularly nearby small business establishments.
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    Multi-city study of an engineering and outreach program to increase driver yielding at signalized and unsignalized crosswalks
    (Minnesota Department of Transportation, 2023-03) Morris, Nichole L.; Craig, Curtis M.; Drahos, Bradley; Tian, Disi; Van Houten, Ron; Mabry, Marshall; Kessler, William
    Pedestrian deaths are at a 30-year high nationally, accounting for 16% of total deaths in 2018 and far exceeding the previous decade of 12%, a trend mirrored in Minnesota. Previous research found an increase in local and citywide yielding at unsignalized crosswalks following an engineering and high-visibility enforcement program in Saint Paul, Minnesota. This study examined a modified engineering-focused (i.e., without enforcement) program expanded to both unsignalized and signalized intersections across the Twin Cities. The six-month study found modest improvements in yielding from baseline to treatment end (48.1% to 65.5% in Saint Paul and 19.8% to 38.8% in Minneapolis) at unsignalized engineering treatment sites but no improvements at generalization sites. No significant improvements in left- or right-turning yielding by drivers in Saint Paul were found at treated signalized intersections, but given that yielding was significantly worse at generalization sites over time, there may be some evidence that treatments mitigated performance declines among Saint Paul drivers during the study period. Yielding improvements at signalized treatment sites were more pronounced for only right-turning drivers in Minneapolis, but generalization sites showed no improvement or even worsened over time. Overall, study results suggested no shift in driving culture in either city, as found with the previous study using police enforcement, but found some evidence of local, site-specific changes in driver yielding behavior at treatment locations.
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    Assessing the Energy Impacts of Cyberattacks on Low-Level Automated Vehicles
    (Center for Transportation Studies, University of Minnesota, 2023-08) Stern, Raphael; Li, Tianyi; Rosenblad, Benjamin; Shang, Mingfeng
    In this study, we investigate the potential impact of stealthy cyberattacks on automated or partially automated vehicles, and consider how they will influence traffic flow and fuel consumption. Specifically, we define stealthy cyberattacks on automated vehicles where driving behavior deviates only slightly from normal driving behavior. We use simulation analysis to consider different cyberattacks, and investigate their impact on traffic flow and aggregate fuel consumption of all vehicles in the traffic flow. We find that such attacks, while difficult to detect, may substantially degrade traffic flow, and, to a lesser extent, vehicle emissions across the traffic flow.
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    Climate Change Adaptation of Urban Stormwater Infrastructure
    (Minnesota Department of Transportation, 2023-06) Erickson, Andrew J.; Herb, William R.; Gallagher, Noah D.; Weiss, Peter T.; Wilson, Bruce N.; Gulliver, John S.
    The final analysis of historical (TP-40), current (Atlas 14), and future predicted storm events for three watersheds in Minnesota (Duluth, Minneapolis, Rochester) has shown that current design philosophy is not sufficient to prevent flooding from 10-year and larger design storm events and that flood depth and duration will increase given current climate projections. Several stormwater infrastructure adaptation strategies were assessed for reducing flood depth and duration: Baseline (existing conditions), adding rain gardens (aka, Infiltration Basins), adding new wet ponds, retrofitting existing stormwater ponds to be ?Smart Ponds, adding new Smart Ponds while also converting existing ponds into Smart Ponds, or upsizing of stormwater pipes to convey more water. In watersheds that are mixed urban, suburban, and rural like Rochester?s Kings Run or Duluth?s Miller Creek sub-watersheds, the most cost-effective climate change adaptation strategy was to build new stormwater wet ponds (Extra Ponds strategy) to treat the impervious surfaces not currently treated by existing wet ponds and other stormwater BMPs. In the fully developed urban 1NE watershed in Minneapolis, the most cost-effective (excluding land costs) climate change adaptation strategy was building wet ponds (Extra Ponds). Securing property for building new stormwater infrastructure in fully developed urban watersheds like 1NE may be a substantial cost compared to other watersheds. Smart Ponds do not require additional land for implementation and thus represent a relatively low-cost alternative that will be more beneficial in watersheds with numerous existing wet ponds.
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    Autonomous Mobile Asphalt Density Profiling Robot to Reduce Worker Risk
    (Center for Transportation Studies, University of Minnesota, 2023-06) Morris, Ted; Papanikolopoulos, Nikolaos
    MnDOT pavement construction personnel have lately improved quality assurance (QA) through the use of nondestructive air coupled ground penetrating radar sensors. Although proving to be accurate, the acquisition process can be manually intensive and hazardous especially when deployed adjacent to prevailing traffic. The primary objective of this project was to deliver to MnDOT two low-cost, modular, highly transportable, mobile robot platforms designed specifically for pavement density profile testing. Several field tests were performed to assess feasibility of the platform under different operational scenarios. Modularity was ensured by integrating separate, distributed, plug-and-play modules that could be reused for other mobile platforms, should the need arise for future implementations. By implementing two robots, the transferability of the architecture was demonstrated. The mobile robotic platforms were purposely assembled from widely available, low-cost, commercial, off-the-shelf components to minimize overall cost, recognizing that the landscape for such platforms has been evolving rapidly.
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    Centering the Margins: The Transportation Experience of Underserved Communities
    (Minnesota Department of Transportation, 2023-08) Fan, Yingling; Greenberg, Gillian; Panchal, Niyati; Wilson, Maxwell; Luna, Christina; Amrhein, Joseph; Benda, Samuel; Song, Ying; Zeng, Xiaohuan
    Transportation systems, as integral parts of human settlements, reflect the societal structures and cultural ideologies influenced predominantly by the dominant race or class. In the absence of prioritizing the transportation needs of underserved communities, transportation systems may perpetuate systematic inequities. This study aims to address the inequities present in current transportation systems by conducting a comprehensive examination of the transportation experiences of individuals belonging to ten specific underserved communities. These communities include eight within the Twin Cities metropolitan region (Latinx, African American, Hmong, people with disabilities, immigrants, people living with HIV, single mothers, and single fathers), as well as two communities in the Greater Minnesota area (transitioning home residents in Fergus Falls and tribal members of the White Earth Nation). This research adopts a mixed-method approach, incorporating both qualitative interviews and quantitative smartphone-based travel behavior surveys. The findings reveal that each community faces distinct transportation barriers, alongside shared themes in transportation inequities such as inadequate public transportation, difficulties related to car use, and the impact of transportation on significant life outcomes. Recommendations for future research and practice are provided.
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    Reducing Winter Maintenance Equipment Fuel Consumption Using Advanced Vehicle Data Analytics
    (Minnesota Department of Transportation, 2023-01) Northrop, William; Challa, Dinesh Reddy; Eagon, Matthew; Wringa, Peter
    This project analyzes the impact that idling and snowfall have on the fuel consumed by MnDOT's snowplow fleet, with the underlying objective to determine and advise MnDOT on ways to reduce fuel usage of the fleet using vehicle telematics data. This is a significant problem to solve as fuel use reduction contributes to MnDOT?s sustainability goals of achieving a 30% reduction in fossil fuel use and greenhouse gas (GHG) emissions from 2005 levels by 2025. Furthermore, rising fuel costs are a future cause for concern due to an increase in business operational costs that increases the burden on taxpayers to keep roads safe in winter. This problem is challenging because existing on-board diagnostics (OBD) data do not contain mass information for the trucks' fuel use, which can fluctuate significantly when they are applying deicing substances to the road. Taking a mean value for the vehicle mass, we observe a clear positive correlation between snowfall and average fuel use. For days with snowfall totaling 4 inches or more, fuel use rises more than 25% on average compared to days without snowfall. In addition, the results from the idling analysis indicate that the idling time associated with the fleet is about 23% of total recorded hours and constitutes about 4.3% of the total fuel used. Daily idling activity reports containing information about idling events and fuel economy are generated for the sampled vehicles and shared with MnDOT.
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    Maximizing Transportation Assets by Building Community Connection Through Innovative Deployment of Rights of Way and Airspace
    (Minnesota Department of Transportation, 2023-06) Douma, Frank; Sheikh, Maya
    This Minnesota Department of Transportation-sponsored research effort examined innovative right-of-way projects nationwide, focusing on how new and innovative practices for redeveloping transportation assets can meet ambitious goals such as mitigating environmental impacts, encouraging placemaking, and enhancing economic opportunity while continuing to meet their transportation purpose. The team explored case studies from across the nation and identified best practices and lessons learned to inform future agencies and planners of new trends in transportation right-of-way projects.
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    Identifying and Optimizing Electric Vehicle Corridor Charging Infrastructure for Medium and Heavy-Duty Trucks
    (Minnesota Department of Transportation, 2023-06) Khani, Alireza; Emami, Behnam Davazdah; Garcia, Fernando; Popenhagen, Brandi
    This project studies the benefits and barriers of increased adoption of medium-duty and heavy-duty electric trucks, referred to as e-trucks, and presents a methodology for optimizing the location of e-truck charging stations in Minnesota. In general, e-trucks provide zero tailpipe emissions and lower operating and maintenance costs. However, some barriers to adopting e-trucks include higher initial purchase costs, lack of charging and maintenance infrastructure, limited range, and charging time. The methods presented in this study aim to address the charging infrastructure planning, which provides information about e-truck charging activities, changes in vehicle miles traveled (VMT), and potential operating cost savings.
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    Stormwater Pond Maintenance, and Wetland Management for Phosphorus Retention
    (Minnesota Department of Transportation, 2023-06) Janke, Benjamin D.; Natarajan, Poornima; Gulliver, John S.; Finlay, Jacques C.
    Reduction in phosphorus is critical because phosphate, a dissolved form of phosphorus, sustains algal and cyanobacteria growth and causes a wide range of water-quality impairments in the ponds and downstream waters including algal blooms, excess floating plants, taste, and odor problems. Many stormwater ponds and wetlands that treat stormwater appear to be less effective than expected or originally intended in phosphorus retention, a key function of these ponds in urban environments. There is evidence that many old ponds are releasing phosphorus from bottom sediments at high rates and likely exporting phosphorus to downstream surface water bodies. A major outcome of this project is a pond Assessment Tool to assess the risk of high phosphorus concentrations in ponds and sediment release of phosphorus. The tool is based on 20 ponds with detailed water quality and phosphorus release measurements and a meta-analysis of 230 ponds in the Twin Cities metro area. Other outcomes included a working definition of a constructed stormwater pond and a wetland treating stormwater in the framework of water-body regulations, the development of recommendations for stormwater pond maintenance and wetland management, and an update to the sections on the constructed stormwater ponds section of the 2009 Stormwater Maintenance BMP Guide.