Minnesota Department of Transportation

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2010 Reports and Technical Summaries

MnDOT Research Services

Orange barrels on a highway

The Influence of Pavement Surface Texture on Traffic Noise

Noise Monitoring

Technical Summary: 201040TS

(PDF, 985 KB, 2 pages)

Full Report: 2010-40

(PDF, 2.9 MB, 153 pages)

Researchers compared the relative loudness of several concrete pavement surface finishes by evaluating test sections. Results showed the innovative/ultimate diamond grind to be the quietest, followed by the burlap drag, conventional diamond grind and transverse tine.

Development of an Advanced Structural Monitoring System

Technical Summary: 201039TS

(PDF, 725 KB, 2 pages)

Final Report: 2010-39

(PDF, 2 MB, 66 pages)

This research selects an advanced warning monitoring device and designs a monitoring plan for a fracture critical bridge.

Improved Automatic Sampling for Suspended Solids


Technical Summary: 201038TS

(PDF, 671 KB, 2 pages)

Full Report: 2010-38

(PDF, 1.6 MB, 37 pages)

Researchers dramatically increased the accuracy of the automatic sampling of suspended solids by creating a device that mixes equal volumes of samples collected from multiple locations in the water column, yielding a combined sample that more closely reflects the average for the water column as a whole.

Incorporating GPS and Mapping Capability into Ground Penetrating Radar (GPR) Operations for Pavement Thickness Evaluations

Final Report: 2010-37

(PDF, 2.9 MB, 49 pages)

Ground Penetrating Radar (GPR) investigations performed by Mn/DOT of pavements and other subsurface features have been limited by an inefficient and poorly documented GPR survey process and underdeveloped project mapping and reporting process. We hope to have improved that.

Pooling Our Research: Evaluating Non-Intrusive Traffic Detection Technologies


Technical Summary: 201036TS

(PDF, 914 KB, 2 pages)

Full Report: 2010-36

(PDF, 5 MB, 100 pages)

Continuing with research that began in 1994, pooled fund TPF-5(171) evaluated the accuracy of the newest generation of non-intrusive traffic detection technologies that collect speed and volume data, and have the added capability of gathering classification data.

A Property-Based Specification for Coarse Aggregate in Pavement Applications

Technical Summary: 201035TS

(PDF, 972 KB, 2 pages)

Final Report: 2010-35

(PDF, 1.4 MB, 95 pages)

This research discusses whether improvements are needed in Mn/DOTs current aggregate specifications and documents the current effort on the relation of property-based to pavement performance from literature and experts.

Minnesota Truck Parking Study (Phase 2)


Technical Summary: 201034TS

(PDF, 1.1 MB, 2 pages)

Full Report: 2010-34

(PDF, 24 MB, 107 pages)

Researchers performed analyses, surveys and literature reviews to better understand Minnesota's truck parking capacity problems and identified specific, low-cost opportunities to expand capacity in the places where it is needed most.

Putting Research into Practice: Training to Support "Hear Every Voice"


Technical Summary: 201033TS

(PDF, 865 KB, 2 pages)

Full Report: 2010-33

(PDF, 361 KB, 50 pages)

Investigators developed and administered a training curriculum on the core principles of MnDOT’s public involvement guidance, designed to assist employees in the planning, implementation and evaluation of public and stakeholder participation.

Preventing the Occurrence of Bumps in HMA Overlays

Crack Seal

Technical Summary: 201031TS

(PDF, 1 MB, 2 pages)

Full Report: 2010-31

(PDF, 3.2 MB, 79 pages)

Researchers identified construction methods and materials for preventing the occurrence of bumps in hot-mix asphalt overlays, finding that best practices include using specified rolling techniques during warmer weather, low-modulus sealants, and narrow and shallow crack sealant reservoirs while avoiding overbanding.

Construction Report for MnROAD Thin Unbonded Concrete Overlay Test Cell 5 (Sub-Cells 105-405)

Final Report: 2010-30

(PDF, 1.7 MB, 62 pages)

This report describes the physical characteristics of the new thin unbonded concrete overlay test cell 5 (sub-cells 105-405). Included in the report are the construction plans (including sensor layouts), quantities and bid prices, as well as the special provisions.

Alkali Silica Reactivity Testing of Four Taconite Ledges for Potential Use as Aggregate in Concrete

Final Report: 2010-29

(PDF, 5 MB, 68 pages)

In response to a request from the Natural Resources Research Institute, Mn/DOT tested four taconite ledges, which may have the potential to be used in concrete, for alkali silica reactivity according to ASTM C 1293, Standard Test Method for Determination of Length of Change Due to Alkali Silica Reaction, and ASTM C 1260, Standard Test Method for Potential Alkali Reactivity of Aggregates. The results of the tests are detailed in this report.

Air Voids Testing for MnROAD Cells

Final Report: 2010-28

(PDF, 991 KB, 52 pages)

This project measures air voids in the lifts of 145 cores extracted from the various cells at MnROAD.

Public Acceptance of New Highway Capacity Strategies: FAST Miles and FEE Lanes


Technical Summary: 201027TS

(PDF, 695 KB, 2 pages)

Full Report: 2010-27

(PDF, 475 KB, 57 pages)

Researchers conducted six focus groups with Minnesota highway users to determine public understanding of a variety of FAST and FEE lane concepts. Participants were generally open to more efficient use of existing infrastructure but expressed concerns about logistics, fairness and safety.

Improving the Quality of MnROAD Pavement Temperature Data

MnROAD Test Track

Technical Summary: 201026TS

(PDF, 965 KB, 2 pages)

Full Report: 2010-26

(PDF, 3 MB, 250 pages)

Researchers created a procedure to flag erroneous data in the MnROAD temperature record database. They also created summary tables and graphs of the resulting reliable data, which can be used by researchers worldwide to develop, test and ultimately improve road designs..

Putting Research into Practice: Guidelines for Designing Turn Lanes


Technical Summary: 201025TS

(PDF, 695 KB, 2 pages)

Full Report: 2010-25

(PDF, 5 MB, 60 pages)

Investigators assembled a guide that identifies and analyzes the primary factors influencing turn lane design. The guide includes a step-by-step process to calculate safe and effective turn lane lengths based on the specific characteristics of each intersection.

Recycling Mining Materials as Durable Aggregates

Recycled Roadway

Technical Summary: 201024TS

(PDF, 940 KB, 2 pages)

Full Report: 2010-24

(PDF, 986 KB, 21 pages)

Researchers evaluated an iron mining byproduct called taconite for use in roads as a high-quality aggregate and found it to be durable. MnROAD test sections using taconite performed as well as or better than those using conventional aggregates.

Construction Report for a Thin Unbonded Concrete Overlay on Minnesota TH 53

Final Report: 2010-23

(PDF, 4 MB, 47 pages)

Mn/DOT included a section of rehabilitated TH 53 with a 5-inch thick concrete overlay as part of a research project looking at thin, unbounded overlays. This report presents the initial baseline testing of the TH 53 test section, which continues to undergo rigorous testing.

Measuring Soil Contaminants Caused by Land Use


Technical Summary: 201022TS

(PDF, 623 KB, 2 pages)

Full Report: 2010-22

(PDF, 5.2 KB, 202 pages)

Researchers evaluated an iron mining byproduct called taconite for use in roads as a high-quality aggregate and found it to be durable. MnROAD test sections using taconite performed as well as or better than those using conventional aggregates.

Responding to the Unexpected: Traveler Behavior and Network Performance in the Wake of the I-35W Bridge Collapse

Bridge Collapse

Technical Summary: 201021TS

(PDF, 709 KB, 2 pages)

Full Report: 2010-21

(PDF, 28 MB, 210 pages)

Researchers evaluated the traveler behavior and the performance of transportation networks in the wake of the I-35W Bridge collapse, advancing understanding of the impacts of full closure compared with staged construction on the safety, quality and cost of construction projects.

Designing Site-Specific Roadside Prairie or Grassland Seed Mixes


Technical Summary: 201020TS

(PDF, 1.2 MB, 2 pages)

Full Report: 2010-20

(PDF, 1.5 MB, 83 pages)

Researchers evaluated the traveler behavior and the performance of transportation networks in the wake of the I-35W Bridge collapse, advancing understanding of the impacts of full closure compared with staged construction on the safety, quality and cost of construction projects.

Mesabi-Select Concrete Pavement Five Year Performance Report

Final Report: 2010-19

(PDF, 4 MB, 38 pages)

This report evaluates the five-year performance of using Mesabi-Slect as coarse aggregate in concrete pavement on Cell 54 on the MnROAD low-volume loop, and found Cell 54 to be in very good condition.

Investigation of Joint Deterioration in MnROAD Phase 1 Jointed Concrete Pavement Test Sections

Final Report: 2010-18

(PDF, 2 MB, 31 pages)

To determine whether the distress observed in MnROAD test sections was unique, researchers examined six other Minnesota concrete pavement projects of similar age and material. Similar types of distress were found but the extent of damage was not as severe and sections with base layers that adequately drained water within the joints performed significantly better.

Update of Vehicle Classification for County Road Pavement Design


Technical Summary: 201017TS

(PDF, 719 KB, 2 pages)

Full Report: 2010-17

(PDF, 470 KB, 50 pages)

Researchers conducted vehicle classification counts in 15 counties across the state. They discovered that the proportion of heavy trucks on the County State Aid Highway system is at least twice as high as the counts found in the latest Pavement Design Manual.

Drainable Pavements at MnROAD Pervious Concrete and Porous Concrete Overlay Cells 39, 85, and 89.

Final Report: 2010-16

(PDF, 1.1 MB, 27 pages)

This report discusses 2009 research activities and test results from Cell 39 Porous Concrete Overlay, Cell 85 Pervious Concrete on Granular Subgrade, and Cell 89 Pervious Concrete on Cohesive Subgrade, all located on the MnROAD low volume road (LVR). Specifically, this report discusses the density tests, porosity analysis, flow tests, and surface characteristic tests performed to collect the data necessary to develop a surface performance/survival algorithm for the cells in this study.

Putting Research into Practice: Establishing a Combined Smoothness Specification for Minnesota Pavements

Concrete Construction

Technical Summary: 201015TS

(PDF, 996 KB, 2 pages)

Full Report: 2010-15

(PDF, 3.3 MB, 180 pages)

Researchers conducted vehicle classification counts in 15 counties across the state. They discovered that the proportion of heavy trucks on the County State Aid Highway system is at least twice as high as the counts found in the latest Pavement Design Manual.

Decision Support for Scour Monitoring on River Bridges

Under Bridge

Technical Summary: 201014TS

(PDF, 904 KB, 2 pages)

Full Report: 2010-14

(PDF, 2.5 MB, 193 pages)

Bridge scour threatens bridge stability and the safety of the traveling public. Researchers developed a decision-making tool that uses the unique bridge and waterway characteristics of individual sites to help bridge operators successfully identify the best fixed scour monitoring methods.

Making Roads and Bridges Resistant to Frost and Ice

Frost Crack

Technical Summary: 201013TS

(PDF, 516 KB, 2 pages)

Full Report: 2010-13

(PDF, 805 KB, 33 pages)

Researchers investigated the effectiveness of the Cargill SafeLane™ anti-icing overlay system on bridge decks and found that while it significantly increased traction and reduced crash rates, it was subject to rapid wear from traffic and snowplows.

Access to Destinations: Arterial Data Acquisition and Networkwide Travel Time Estimation (Phase II)

Metro Area

Technical Summary: 201012TS

(PDF, 1 MB, 2 pages)

Full Report: 2010-12

(PDF, 2.2 MB, 49 pages)

Researchers used updated traffic demand volume and signal timing data to calculate travel time estimates for arterial links in the Twin Cities region. The new data can be used to evaluate changes in the transportation network over time and to develop accessibility measurements for the region.

Wetland Mitigation in Abandoned Gravel Pits

Technical Summary: 201011TS

(PDF, 1.3 MB, 2 pages)

Full Report: 2010-11

(PDF, 806 KB, 59 pages)

It is becoming increasingly difficult to provide on-site mitigation for wetland impacts due to road construction in northeastern Minnesota counties which retain greater than 80 percent of their pre-settlement wetlands. Abandoned gravel pits are one of the few remaining areas which can serve as wetland mitigation sites within the impacted watersheds. The main goal of the project is to determine if viable mitigation wetlands can be created on abandoned gravel pit sites to compensate for wetland impacts due to road construction in northeastern Minnesota.

Assessment of Underground Stormwater Management Devices Under High Flow Conditions


Technical Summary: 201010TS

(PDF, 931 KB, 2 pages)

Full Report: 2010-10

(PDF, 8.5 MB, 130 pages)

Researchers developed tests for measuring the amount of sediment washed out of hydrodynamic separators during high flow storm events. These tests have aided in creating computer models that will be used to predict efficiencies for any manufacturer’s separator under varying conditions and environments.

Access to Destinations: Measuring Accessibility by Automobile

Metro Area

Technical Summary: 201009TS

(PDF, 1.2 MB, 2 pages)

Full Report: 2010-09

(PDF, 115 MB, 312 pages)

Researchers analyzed accessibility measures—which indicate proximity to opportunities like jobs, rather than simply travel times—for the Twin Cities metropolitan area between 1995 and 2005. Overall, the region is becoming more accessible due to both land use changes and transportation network improvements.

Incorporation of Recycled Asphalt Shingles in Hot Mix Asphalt Pavement Mixtures

Full Report: 2010-08

(PDF, 3.5 MB, 83 pages)

The goal of this research was to determine whether the environmental goals of responsibly incorporating recycled asphalt shingles into hot mixed asphalt were realized while still maintaining or improving pavement durability.

Automating Friction Measurement and Applicator Control for Snowplows


Technical Summary: 201007TS

(PDF, 893 KB, 2 pages)

Full Report: 2010-07

(PDF, 1.5 MB, 61 pages)

Researchers developed an automated system that continuously measures the friction coefficient of the pavement and quickly detects any change, activates/deactivates the snowplow applicator based on the friction measurement and applies the appropriate amount of deicing material on the road surface.

Analysis of Practical Methods for Counting Bicycles and Pedestrians


Technical Summary: 201006TS

Full Report: 2010-06

Researchers evaluated current automated methods for counting bicycle and pedestrian traffic in a transportation network and developed a prototype vision-based computer program with the goal of improving accuracy and reducing long-term costs.

State of Practice for Minnesota Local Agency Pavement Marking Management

Pavement Marking

Technical Summary: 201005TS

(PDF, 612 KB, 2 pages)

Full Report: 2010-05

(PDF, 1.6 MB, 41 pages)

Investigators surveyed Minnesota local transportation agencies regarding their practices for managing the maintenance of their pavement markings and produced recommendations for best practices in this area.

TH-36 Full Closure Construction: Evaluation of Traffic Operations Alternatives


Technical Summary: 201004TS

(PDF, 588 KB, 2 pages)

Full Report: 2010-04

(PDF, 6 MB, 155 pages)

Researchers evaluated the impact of the first large-scale full closure construction project in Minnesota. They found full closure to be a viable, cost-saving construction alternative under these circumstances and gained valuable knowledge of the tools used to evaluate future project alternatives.

Discrepancies in the Shear Strength of Prestressed Beams with Different Specifications

Bridge Road

Technical Summary: 201003TS

(PDF, 594 KB, 2 pages)

Full Report: 2010-03

(PDF, 13 MB, 242 pages)

Previous studies have revealed discrepancies between load rating calculations and the expected carrying capacity based upon visual inspections of bridges. In this study, researchers investigated possible sources of these discrepancies and suggested some remedies.

Using Dual-Phase Message Signs to Display Airline Information

Technical Summary: 201002TS

(PDF, 603 KB, 2 pages)

Full Report: 2010-02

(PDF, 671 KB, 81 pages)

Researchers used a driving simulator to compare the use of overhead dual-phase to multiple static Changeable Message Signs for effectiveness in conveying airline information to highway drivers approaching the Minneapolis-St. Paul International Airport. Researchers found that the two methods were equally effective.

Evaluating Workforce Perceptions to Identify and Mitigate the Causes of Musculoskeletal Disorders

Construction Workers

Technical Summary: 201001TS

(PDF, 360 KB, 2 pages)

Full Report: 2010-01

(PDF, 338 KB, 32 pages)

Researchers interviewed transportation employees to discover their perceptions of workplace safety to reduce on-the-job injuries. They found that employees' primary concern—contact with public vehicles—needed to be addressed before a successful program to reduce musculoskeletal disorder injuries can be implemented.

Fly Ash: Stabilizing the Base

Fly Ash Paving

Technical Summary: Fly Ash

(PDF, 216 KB, 2 pages)

Many states currently use fly ash to stabilize foundation materials during road construction projects. In Minnesota, the recent implementation of new specifications, tools, and projects at the local level is supporting increased use within the state.

In 1994, the Minnesota Local Road Research Board (LRRB) funded a study that explored the use of several materials, including fly ash, to stabilize soils for road reconstruction projects. The LRRB also supported follow-up studies, including evaluations of several demonstration projects.

Putting Research into Practice: Maintaining Guardrails for Roadside Safety

Bullnose Guardrail

Technical Summary: 2010RIC13TS

(PDF, 855 KB, 2 pages)

Full Report: 2010RIC13

(PDF, 1.4 MB, 38 pages)

Guardrail maintenance is a key component of protecting the roadside, but there is uncertainty as to how to maintain the various guardrails and end treatments that are currently in use. Local jurisdictions continue to perform guardrail maintenance but there are no current guidelines to ensure that maintenance practices are to standard and are consistent throughout the state. These guidelines summarize current issues, the accepted approved guardrail types and end treatments used in Minnesota, inspection and maintenance practices for guardrails and resources and standards on guardrails and end treatments. Appendices A and B provide quick reference sheets to highlight the guardrails and end treatments currently used in Minnesota and the suggested use of each type.

Putting Research into Practice: Best Practices for Removing Traffic Signs


Technical Summary: 2010RIC10TS

(PDF, 773 KB, 2 pages)

Full Report: 2010RIC10

(PDF, 5.8 MB, 111 pages)

The goal of this project was to identify perceived roadblocks to removing unnecessary signs and to develop a best practices guide based on that information. The guide would address technical issues and provide guidelines for developing policies for removing unnecessary signs.

Putting Research into Practice: Maintaining Safer Local Roadways

Road Safety

Technical Summary: 2010RIC03TS

(PDF, 824 KB, 2 pages)

Full Report: 2010RIC03

(PDF, 604 KB, 22 pages)

The Local Road Research Board has developed a workshop on "Maintaining a Safer Roadway" that provides education to maintenance staff on how they can make our roads safer. Local Agency maintenance forces are in the best position to be the "eyes and ears" for Local Agencies when it comes to identifying situations, that when addressed, could greatly improve safety for the traveling public.

Putting Research into Practice: Establishing a Sign Retroreflectivity Maintenance Program


Technical Summary: 2010RIC02TS

(PDF, 746 KB, 2 pages)

Full Report: 2010RIC02

(PDF, 5.4 MB, 58 pages)

The Minnesota LRRB has developed a Sign Retroreflectivity Toolkit that is designed to provide local governments, especially small cities and townships, with guidance on FHWA's sign retroreflectivity deadlines as well as resources they can use to meet these deadlines.

Pooling Our Research: Improving Transportation Management Center Performance

Traffic Management

Technical Summary: 2010SPR-2(207)

(PDF, 1 MB, 2 pages)

Project Page

SPR-2(207): Transportation Management Center Pooled Fund Study. This ongoing study provides technical guidance, best practices, training, innovative techniques and technologies, and fact-based tools to help transportation management centers improve services and performance.

Pooling Our Research: Developing Technologies to Predict Winter Road Conditions

Embedded Sensor

Technical Summary: 2010SPR-2(042)TS

Project Page

SPR-3(042): Aurora Program Pooled Fund Study. Aurora is an internationally recognized leader in the research and development of road and weather information systems, including winter and pavement condition forecasting technologies. MnDOT has been a member of this program since its inception in 1996.

Pooling Our Research: Accelerating the Development of Intelligent Transportation Systems

Winter Sign

Technical Summary: 2010SPR-3(020)TS

Project Page

ENTERPRISE facilitates the rapid development of intelligent transportation systems, allowing Minnesota to benefit from the latest technologies for increasing highway safety and efficiency, and reducing congestion and the environmental impacts of travel.

Pooling Our Research: Improving Winter Maintenance with New Technologies

Snow Plow

Technical Summary: 2010TPF-5(218)TS

Project Page

Launched in 2004, the Clear Roads Winter Highway Operations Pooled Fund is aimed at rigorous testing of winter maintenance materials, equipment and methods for use by highway maintenance crews.

Pooling Our Research: The Transportation Curriculum Coordination Council


Technical Summary: 2010TPF-5(209)TS

Project Page

Transportation Curriculum Coordination Council. This effort helps states train and certify personnel through national core curriculum and training materials for various transportation disciplines, providing the most comprehensive Web-based training resource available to the transportation community today.

Pooling Our Research: Innovative Technologies to Improve Motorist Safety During Roadside Crashes

Crash Figure

Technical Summary: 2010TPF-5(193)TS

Project Page

Now in its 19th year, the FHWA's Midwest States Pooled Fund Crash Test Program is dedicated to making roadsides less hazardous to motorists by evaluating roadside safety hardware such as guardrails and median barriers. The program is hosted by the University of Nebraska's Midwest Roadside Safety Facility, which is also recognized as a global leader in the development of innovative roadside safety features, such as Minnesota's thrie-beam bullnose median terminal.

Pooling Our Research: Updating Precipitation Frequency Estimates.

US Map

Technical Summary: 2010TPF-5(187)TS

Project Page

Updating U.S. Precipitation Frequency Estimates for the Midwestern Region. This multistate pooled fund study is updating decades-old precipitation frequency estimates that are used by practitioners to design small drainage structures such as inlets, storm drains and small culverts.

Pooling Our Research: The Mississippi Valley Freight Coalition


Technical Summary: 2010TPF-5(156)TS

Project Page

Mississippi Valley Freight Coalition. This pooled fund study supports projects focused on the operation, preservation and improvement of freight transportation infrastructure and networks involving the coalition's 10 member states in the Mississippi Valley region.

Pooling Our Research: Providing Transportation Planners with Accurate Census Data


Technical Summary: 2010TPF-5(154)TS

Project Page

Census Transportation Planning Products (CTPP) from the American Community Survey Pooled Fund Study. This study works in conjunction with AASHTO's Standing Committee on Planning on a project to incorporate annual data from the American Community Survey in a set of special data tabulations used for transportation planning and policy analysis.

Pooling Our Research: Enhancing Teen Driver Safety with Video Feedback Systems

Teen Driver

Technical Summary: 2010TPF-5(144)TS

Project Page

Researchers evaluated whether the use of an event-triggered video system within vehicles could reduce the number of safety-relevant driving errors made by newly licensed teens. Researchers found that video feedback was immediately and extremely effective, reducing the number of safety-relevant events by 61 percent overall. There was high user acceptance, and the system increased communication between parents and teens regarding safety.

Pooling Our Research: Making Roadsides Safer


Technical Summary: 2010TPF-5(114)TS

Project Page

TPF-5(114): Roadside Safety Research Program. This study was established in 2005 to crash-test and evaluate the design of roadside structures. More than 25 projects have been completed that support Minnesota's goal to reduce fatalities and serious injuries on its roads.

Pooling Our Research: Increasing the Accessibility of Transportation Research

MnDOT Library

Technical Summary: 2010TPF-5(105)TS

Project Page

TPF-5(114): Roadside Safety Research Program. This study was established in 2005 to crash-test and evaluate the design of roadside structures. More than 25 projects have been completed that support Minnesota's goal to reduce fatalities and serious injuries on its roads.

Pooling Our Research: Cost-Effective Strategies for Making Roads Safer


Technical Summary: 2010TPF-05(099)TS

Project Page

TPF-5(099): Evaluation of Low Cost Safety Improvements. With participation from 28 states, this program is conducting a 10-year evaluation of more than 20 low-cost strategies for making roads safer by reducing crashes and crash severity.

Pooling Our Research: Automating Winter Maintenance Decision Support


Technical Summary: 2010TPF-5(054)TS

Project Page

TPF-5(054): Development of Maintenance Decision Support System Pooled Fund Study. This study was launched to develop and implement an automated software tool that provides real-time winter maintenance treatment recommendations.

Pooling Our Research: Southeastern Superpave Center

Superpave Center

Technical Summary: 2010TPF-5(037)TS

Project Page

Southeastern Superpave Center. The Southeastern Superpave Center helps states implement the Superpave system for more durable asphalt pavements. MnDOT asked center researchers to compare the tire-pavement loudness of several Minnesota pavement surface textures using the center's close-proximity trailer.

Pooling Our Research: Reducing Congestion with HOV Toll Lanes


Technical Summary: 2010TPF-5(029)TS

Project Page

High Occupancy Vehicle/Managed Use Lane Pooled Fund Study. Since 2002, this study has allowed states to address key challenges common to public agencies responsible for managing and operating HOV facilities by providing an avenue to collectively develop more efficient HOV operations methods.