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2005 Reports and Technical Summaries

Orange barrels on a highway

2005 Reports and Technical Summaries


Tools for Predicting Usage and Benefits of Urban Bicycle Network Improvements

Full Report: 2005-50

This report presents the results of four separate studies regarding the behavior of bicyclists in and around the Twin Cities metropolitan area. 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.


Impact of Alternative Storm Water Management Approaches on Highway Infrastructure

Technical Summary: 200549TS
Full Report: 2005-49A, 200549B

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

Full Report: 2005-48

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

Full Report: 2005- 47

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

Full Report: 2005- 46 (PDF, 1.2 MB, 78 pages)

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

Full Report: 2005- 45 (PDF, 14.7 MB, 115 pages)

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

Full Report: 2005-44

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.

2005- 43

Impact of Increasing Roadway Construction Standards on the Life-Cycle Costs of Local Residential Streets

Full Report: 2005- 43 (PDF, 1 MB, 116 pages)

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

Full Report: 2005- 42 (PDF, 3 MB, 71 pages)

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

Full Report: 2005- 41

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

Full Report: 2005- 40 (PDF, 4.2 MB, 56 pages)

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

Full Report: 2005- 39 (PDF, 1.9 MB, 209 pages)

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.


Analysis of Girder Differential Deflection and Web Gap Stress for Rapid Assessment of Distortional Fatigue Stress in Multi-Girder Steel Bridges

Full Report: 2005- 38

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.


Evaluation of Portable Non-Intrusive Traffic Detection System

Full Report: 2005- 37 (PDF, 1.3 MB, 58 pages)

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.


Enhanced Coordination of Cadastral Information

Full Report: 2005- 36

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.


The Financial Benefits of Early Acquisition of Transportation Right of Way

Full Report: 2005- 35

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.


Best Practices for Project Construction Streamlining

Full Report: 2005- 34

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.


State Aid Concrete Pavement Rehabilitation (CPR) Best Practices Manual

Full Report: 2005- 33 (PDF, 1 MB, 63 pages)

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.


Improvement and Validation of Mn/DOT DCP Specifications for Aggregate Base Materials and Select Granular

Full Report: 2005- 32

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

Full Report: 2005- 31

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.


Driver Assistive Systems for Rural Applications: A Path to Deployment

Full Report: 2005- 30

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.


Test and Validation of a Model for Forecasting Frost on Bridges

Full Report: 2005- 29

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.


Occurrence of Bumps in Overlays

Full Report: 2005- 28 (PDF, 2.2 MB, 77 pages)

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.


Synthesis of Current Minnesota Practices of Thin and Ultra-Thin Whitetopping

Full Report: 2005- 27 (PDF, 605 KB, 43 pages)

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.


Preliminary Laboratory Investigation of Enzyme Solutions as a Soil Stabilizer

Full Report: 2005- 25

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.


User Perspectives on Location Efficient Mortgages & Car Sharing

Full Report: 2005- 24

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.


The Cost and Effectiveness of Stormwater Management Practices

Full Report: 2005-23

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

Full Report: 2005-22 (PDF, 16 MB, 315 pages)

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.


Trucks and Twin Cities Traffic Management

Full Report: 2005-21

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.


Route Preferences and the Value of Travel-Time Information for Motorists Driving Real-World Routes

Full Report: 2005-20

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.


Development of a Web-Based Economic Impact Calculator for Small and Medium Size Airports

Full Report: 2005-19 (PDF, 4.3 MB, 46 pages)

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.


DGPS-Based Gang Plowing

Full Report: 2005-18

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.


Telework, Telecommunications and Community Design

This project will: 1) establish an ongoing forum for reviewing State and Local Policy Program (SLPP) research activities and products in as objective, independent and credible a manner as possible; 2) refine measures of sustainable transportation and enhance their applicability in community and regional planning and policy making; and 3) develop in-depth information about the behavioral issues surrounding telework and develop a set of integrated ITS and telecommunications design, planning and evaluation guidelines for communities based upon telework attitudes and behavior.


The Effects of In-Lane Rumble Strips on the Stopping Behavior of Sleep-Deprived Drivers

Full Report: 2005-16

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.


Cost/Benefit Study of: Spring Load Restrictions

Full Report: 2005-15

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 Behind A Retaining Wall

Full Report: 2005-14

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


Retrofitting Shear Cracks in Reinforced Concrete Pier Caps Using Carbon Fiber Reinforced Polymers

Full Report: 2005-13

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.


Project Management Software: Practical Applications for Improved Project Management

Full Report: 2005-12 (PDF, 279 KB, 31 pages)

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.


Partners for Good: A Resource Guide for Partnership Efforts in Minnesota Cities and Counties

Full Report: 2005-11 (PDF, 555 KB, 68 pages)

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.


The Effect of Minnesota Aggregates on Rapid Chloride Permeability Tests

Full Report: 2005-10 (PDF, 2.6 MB, 82 pages)

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.


Economics of Upgrading an Aggregate Road

Full Report: 2005-09 (PDF, 496 KB, 72 pages)

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.


Distillate Usage Patterns in Minnesota: Development of Data and Tools To Analyze Policies Affecting Biodiesel Usage

Full Report: 2005-08 (PDF, 251 KB, 46 pages)

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.


Continuous Compaction Control Demonstration

Full Report: 2005-07 (PDF, 4.8 MB, 139 pages)

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.


Moisture Retention Characteristics of Base and Sub-base Materials

Full Report: 2005-06 (PDF, 536 KB, 112 pages)

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.


Impacts of Overweight Implements of Husbandry on Minnesota Roads and Bridges

Full Report: 2005-05 (PDF, 1 MB, 13 pages)

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.


GPS Based Real-Time Tire-Road Friction Coefficient Identification

Full Report: 2005-04 (PDF, 4 MB, 92 pages)

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.


Screening Tool for Using Waste Materials in Paving Projects (STUWMPP)

Full Report: 2005-03 (PDF, 649 KB, 38 pages)

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.


Recycyled Asphalt Pavement (RAP) Effects on Binder and Mixture Quality

Full Report: 2005-02 (PDF, 1.2 MB, 74 pages)

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)

Handbook (PDF, 487 KB, 23 pages)

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.