August 2011 – Vol. 5, No. 3 Partnering for Roadway Innovation

TERRA E-News is a quarterly electronic newsletter of the Transportation Engineering and Road Research Alliance. TERRA E-News brings you the latest research on pavement, materials, and related transportation engineering challenges, including issues related to cold climates.

MEMBER NEWS

Member Research Spotlight: Implementing the MEPDG in Michigan

Each TERRA member organization will have an opportunity to briefly share and showcase a specific research project or initiative in the Member Research Spotlight. Profiles of most TERRA member organizations, previously published here, remain available through the TERRA E-News archives. Details about this edition’s featured research project were provided by the Michigan Department of Transportation (MDOT).

Problem

MDOT’s current pavement designs are guided by the 1993 American Association of State Highway and Transportation Officials (AASHTO) Guide for the Design of Pavement Structures, which is based on the results of a large-scale road test conducted in the late 1950s. Current road and traffic conditions, however, are significantly different from those that existed half a century ago, and applying these design approaches to present-day situations is no longer appropriate in many cases.

In 2004, AASHTO published the Mechanistic-Empirical Pavement Design Guide (MEPDG), which combines both empirical and mechanistic design approaches into a single guide. After the guide’s release, MDOT needed to determine if and how the MEPDG should be implemented in Michigan.

Solution

MDOT has completed a series of research projects to assess the MEPDG. Research began with a sensitivity analysis that included analyzing the performance of pavement sample sections and comparing the results to the predicted outputs from models used in the MEPDG software.  Another study examined the Michigan-related traffic data needed to replace the default values included in the program, and several other projects investigated materials-related input values.

Overall research results indicate that, with proper calibration, the MEPDG can successfully predict how changes in material and design will affect pavement performance in Michigan. The studies also found the MEPDG to be a powerful tool for analyzing the performance of existing roadways.

Implementation

Because the MEPDG has shown significant promise for improving pavement design in Michigan, MDOT is launching a new study to prepare for the guide’s implementation. Scheduled to begin in fall 2011, the new study will characterize Michigan’s typical HMA mixtures to determine appropriate MEPDG input values, evaluate MEPDG’s pavement rehabilitation designs, and calibrate and validate the predictive models using the performance of existing pavements.

Project Partners

Michigan State University and Michigan Technological University have partnered with MDOT on MEPDG-related research projects.

More Information

• MDOT Research Spotlight: Implementing the Mechanistic-Empirical Pavement Design Guide in Michigan (274 KB PDF)
• MDOT Research Spotlight: Fitting Traffic Data into Mechanistic-Empirical Pavement Design (340 KB PDF)
• Mechanistic-Empirical Pavement Design Guide (TRB, 2004)
• Contact: Michael Eacker, 517-322-3474, eackerm@michigan.gov

Member Highlights

Shoreview public works director Mark Maloney, chair of the TERRA Research and Implementation Committee, received the 2011 Professional Manager of the Year Award in the category of engineering and technology by the American Public Works Association. Maloney is one of two Minnesota Local Road Research Board (LRRB) representatives on the TERRA board.

Several TERRA members were exhibitors at the National Association of County Engineers (NACE) Conference in Minneapolis on April 17 and 18, 2011: American Concrete Pavement Association, American Traffic Safety Services Association - Northland Chapter, Concrete Paving Association of Minnesota, Caterpillar, Minnesota Asphalt Pavement Association, Michigan Technological University, Minnesota Local Road Research Board (LRRB), and Road Science.

The National Concrete Pavement Technology Center (CP Tech Center) at Iowa State University (ISU) in March published Development of Performance Properties of Ternary Mixtures: Laboratory Study on Concrete. The project evaluated cementitious materials combinations that will perform well in different environmental and climatic conditions. This phase of the work focused on concrete mixtures that have desired properties in both the construction and hardened phases in cold weather, hot weather, freeze-thaw cyclic conditions, and where road salts and corrosion may be factors in the life cycle of the concrete elements.

The Minnesota Department of Transportation (MnDOT) has received its ninth National Perpetual Pavement Award from the Asphalt Pavement Alliance. The award-winning section is on Highway 61 in District 1 near Silver Bay, Minnesota. The criteria for this prestigious national award are asphalt pavements that are 35 years or older, have not had major structural failure, have on average at least 13 years between overlays, and demonstrate excellence in design, quality in construction, and value to the traveling public. MnDOT has the national record of nine Perpetual Pavement Awards.

The Interstate 35 Mega Project in Duluth is the first large-scale project in the nation to use Next Generation Concrete Surface (NGCS). MnDOT included the experimental pavement grinding technique on portions of the existing concrete road surface. NGCS grooving not only restores traction on wet and icy days and improves the overall ride but also reduces tire-pavement noise by as much as 6 decibels.

In May, MnDOT announced the Better Roads for a Better Minnesota infrastructure improvement program. The four-year, $398 million program, aimed at improving highways rated in ‘poor’ condition, also will support approximately 9,900 direct and indirect, private sector jobs statewide. Current state and federal funds as well as previously authorized bonds will fund the program. State performance measures currently show that about 750 miles of trunk highway in Minnesota are classified as ‘poor’ condition. Without additional investment, the number of miles in ‘poor’ condition is estimated to increase to 1,900 by the year 2020.

Thirty youth are converging this summer on the campus of Michigan Technological University to participate in Michigan's third National Summer Transportation Institute. The program, funded by the Federal Highway Administration, provides a two-week exploratory program in the science, technology, engineering, and mathematics fields supporting the transportation industry. Unique program highlights include site visits to the Soo Locks, Isle Royale National Park, and the International and Mackinac bridges. Classroom instruction builds upon the AASHTO TRAC program modules and is enhanced with role model speakers, field trips, and modal activities. Students in the program learn about the needs of the transportation industry and about opportunities for education preparing them as future transportation professionals.

PROJECTS AND INITIATIVES

Depletion of local aggregate sources adds to the cost of roads

Areas around the country have been feeling the effects of local depletion of aggregates, which has financial and logistical repercussions for road construction and maintenance. The problem, which was described as early as the 1940s, is multifaceted. Some areas in the country do not have the natural deposits of the high-quality gravel needed for road construction. Other areas do have high-quality gravel, but public perception, land-use policies, and conservation efforts restrict access to the aggregates. Any combination of these barriers contributes to local aggregate shortages across most of the country, particularly in urban areas.

As local aggregates become less available, aggregates must be transported from more distant sites. Bill Langer, a research geologist with the U.S. Geological Survey, said that price savings from more efficient aggregate production operations in recent years have been offset by the high cost to transport aggregates further. In Florida, for example, aggregates must be shipped from as far away as Nova Scotia because the state does not have naturally occurring high-quality aggregates.

According to Fred Corrigan, executive director of the Aggregate and Ready Mix Association of Minnesota (ARM) and TERRA board member, the cost of aggregate doubles every 12 miles the aggregate must be transported—a cost that is passed along to governments and taxpayers. Using aggregate from sources that are farther away from construction jobs increases costs significantly.

One obstacle to mining for aggregates is public perception. Most communities oppose having mining operations nearby, which makes it hard for companies to get permits. Though there are examples of aggregate mining operations that have good relationships with their neighbors, many people still are fearful of allowing a new mining operation in their backyard, Langer said.

Dennis Martin, manager of the mineral potential section with the Minnesota Department of Natural Resources (DNR), said that many depleted gravel pits are not reclaimed. As a result, the public often thinks there are enough sources even though there may be no usable gravel left in a pit, he explained. “The public may think that we already have a gravel pit,” Martin said, “so why would we mine for more?”

But mines can easily be reclaimed in an environmentally responsible way and can become housing developments or prairie lands, Martin added. For example, downtown Maple Grove, Minnesota, was built on a reclaimed gravel mine.

Another factor is that higher quality standards for aggregates used in asphalt mixes such as Superpave mean that only 10 percent of the aggregates mined from a single gravel pit will be usable for road paving. Larry Zanko, a research fellow at the Natural Resources Research Institute at the University of Minnesota Duluth, has been researching the use of coarse taconite tailings, a byproduct of taconite (lower-grade iron ore) mining. Coarse taconite tailings are abundant, with millions of tons produced annually in Minnesota, and usable for road paving. However, because taconite tailings are heavy and would need to be transported long distances by rail, the cost currently is not competitive.

In Minnesota, the Minnesota Department of Transportation (MnDOT) and the DNR have started to make maps of areas with the remaining aggregate available to counties for land-use planning. In addition, MnDOT and the DNR, in partnership with the Aggregate and Ready Mix Association of Minnesota, have begun to educate Minnesota lawmakers about the potential for new local sources. There will be enough local aggregates to meet needs while addressing the concerns of the public, they said, if leaders plan well.

Related resources:

• Aggregate and Ready Mix Association of Minnesota
• Minnesota Department of Natural Resources Division of Lands and Minerals
• Natural Resources Research Institute (University of Minnesota Duluth)
• National Stone, Sand & Gravel Association
• U.S. Geological Survey Construction Sand and Gravel Statistics and Information

Road construction projects incorporate low-cost engineering safety improvements

Due to efforts at the federal, state, and local level, America’s roads have become safer. However, nearly 34,000 motor vehicle fatalities still occur each year in this country. To support the continued work of the many individuals and organizations dedicated to reducing the number of fatal and severe injury crashes on U.S. roadways, the Federal Highway Administration has required safety plans for every state.

A new TERRA fact sheet describes some of the easy-to-implement, low-cost, and effective engineering safety improvements DOTs can integrate into their road building and restoration programs.

Two of the most deadly crash types are road/lane departures and intersection crashes. The National Highway Traffic Safety Administration (NHTSA) reports that nationwide, nearly 4 of every 10 fatal motor vehicle crashes involve a single vehicle leaving the roadway, with more than twice as many lane departure fatal crashes on rural roads than on urban roads.

In 2009, there were 33,808 fatalities on U.S. roadways. Of these, 7,043—20.8 percent—were intersection or intersection-related. Clearly, intersections represent a disproportionate share of the safety problem, partly because they present some of the most complex traffic situations drivers encounter. The dangers are compounded with the addition of speeding motorists who disregard traffic controls. The main issues in metropolitan areas are angle crashes at signalized intersections; on rural roads the issues are right-angle crashes at stop-controlled intersections.

TERRA members are using many low-cost, effective strategies to prevent fatal and serious injury crashes. For example, the New York State Department of Transportation (NYSDOT) is using pedestrian countdown timers and raised crosswalks to implement intersection crash-reduction strategies. To reduce the number of road/lane departure crashes, NYSDOT uses safety edges on hot-mix pavement, rumble strips along pavement edges and centerlines, high-visibility signpost wraps, and cable median barriers (NYSDOT developed a nonproprietary, four-cable, low-tension median barrier).

The Minnesota Department of Transportation (MnDOT) uses confirmation lights, flashing yellow arrows, and optimized signal timing to reduce crashes at urban intersections. At rural thru-stop intersections, MnDOT uses the signing and marking package as seen in the MnDOT Traffic Safety Fundamental Handbook. To prevent road/lane departure crashes, MnDOT uses rumble strips and stripes, high-performance pavement markings, chevrons in curves, curve widening (high and low sides), and rumbles on the high side.

Related resources:

1. Low-Cost Engineering Infrastructure Safety Improvements (TERRA fact sheet)
2. FHWA Safety Program
3. AASHTO Strategic Highway Safety Plan
4. Guides for implementing NCHRP Report 500 Strategies, Volumes 1-19
5. MnDOT Traffic Safety Fundamental Handbook (39.4 MB PDF)

ANNOUNCEMENTS

TERRA Innovation Series: MnROAD research conference postponed

The MnROAD Research Conference  scheduled for Tuesday, August 16, has been postponed due to Minnesota's state government shutdown. TERRA plans to announce a new date for the event, which is part of the TERRA Innovation Series. Details will be posted to the conference web page as they become available. For more information, please contact Stephanie Malinoff, malinoff@umn.edu, 612-624-8398.

Concrete workshop for professors, Aug. 1-5

The Portland Cement Association (PCA) is offering a new, combined PCA Professors’ Workshop from August 1-5, 2011, at the PCA headquarters in Skokie, Illinois. This year introduces a new format, which includes tracks covering engineering and economics of concrete buildings, design and construction of concrete bridges by the AASHTO LRFD, concrete materials properties, and design, construction, and performance of concrete pavements. The Professors’ Workshop is designed to provide faculty in engineering, architecture, and construction management programs the tools to teach the latest developments in concrete design, construction, and materials. TERRA members CP Tech Center and the American Concrete Pavement Association are cosponsors.

International concrete sustainability conference and industry day, Aug. 9–11

The National Ready Mixed Concrete Association is holding the 2011 International Concrete Sustainability Conference from August 9–11, in Cambridge (Boston), Massachusetts, at the Hyatt Regency Cambridge and the Massachusetts Institute of Technology Campus. The sixth annual conference will provide learning and networking opportunities on the latest advances, technical knowledge, continuing research, tools, and solutions for sustainable concrete manufacturing and construction. The conference is being held in conjunction with the MIT Concrete Sustainability Hub 2011 Industry Day on August 11, 2011.

2012 TERRA Pavement Conference planners seek topic ideas by Aug. 12

The TERRA Pavement Conference is scheduled for February 9, 2012, at the University of Minnesota Continuing Education and Conference Center in St. Paul, Minnesota. The conference planning committee is seeking topic ideas for the conference. To suggest topics or issues you would like to see covered, please complete the online form or contact Stephanie Malinoff, malinoff@umn.edu or 612-624-8398. Submissions are due by Friday, August 12, 2011.

This one-day conference provides practical information to practitioners and others interested in pavement design, construction, rehabilitation, and maintenance. The emphasis of the conference is new materials and methods that can assist decision makers in providing the most cost-effective strategies for building, repairing, and maintaining pavement infrastructure. The conference agenda and registration information will be posted on the 16th Annual TERRA Pavement Conference web page in December.

Mid-Continent Transportation Research Symposium, Aug. 18–19

The annual 2011 Mid-Continent Transportation Research Symposium is scheduled for August 18–19, 2011, at Iowa State University, Ames, Iowa. The focus of this year’s symposium is on promising, implementation-ready solutions for federal and state departments of transportation, cities, and counties. The symposium covers a broad spectrum of transportation issues, ranging from current advances in infrastructure design to transportation policy. Several concurrent sessions will be offered, each focused on a specific topic. More information is online about potential topics, review criteria, and formatting. Symposium registration will be available later this month.

Asphalt Shingle Recycling Forum, Oct. 27–28

The 5th Asphalt Shingle Recycling Forum, “A New Era In Asphalt Shingle Recycling­–Tear Off Recycling Comes Of Age,” is scheduled for October 27­–28, 2011, in Dallas, Texas. Texas is rapidly becoming one of the hottest areas in North America for the use of recycled asphalt shingles and other roofing materials. The forum is intended for those entering the market and others looking for the latest technical information on the use of recycled shingles. This is the industry's meeting place—a chance to share and learn from the experts about the rapidly expanding asphalt shingle recycling industry. In addition, vendors and suppliers to the industry will have displays at the event.

CPAM upcoming events

The Concrete Paving Association of Minnesota (CPAM) calendar includes these upcoming events:

• American Concrete Pavement Association (ACPA) Annual Meeting,
  November 30–December 2, 2011
  Hyatt Grand Champions Resort, Indian Wells, California
• CPAM Annual Concrete Paving Workshop, March 8–9, 2012
  Mankato, Minnesota

MAPA upcoming events

The Minnesota Asphalt Pavement Association calendar includes three upcoming events:

• MAAPT 58th Annual Asphalt Conference, December 7, 2011
  Doubletree Hotel, St. Louis Park, Minnesota
  Info: info@mn-aapt.org
• 56th Annual Asphalt Contractors’ Workshop/Quality Initiative Workshop, March 6, 2012
  Earle Brown Heritage Center, Brooklyn Center, Minnesota
  Info: info@mnapa.org
• NAPA 57th Annual Membership Meeting, January 22-25, 2012
  JW Marriott Desert Springs Resort, Palm Desert, California
• World of Asphalt Show & Conference, March 13-15, 2012
  Charlotte Convention Center, Charlotte, North Carolina
• AAPT 87th Annual Meeting, April 1-4, 2012
  Omni Austin Hotel Downtown, Austin, Texas
  Info: aaptinfo@gmail.com

ATSSA annual convention and traffic expo, Feb. 12–16, 2012

The American Traffic Safety Services Association (ATSSA) 42nd Annual Convention and Traffic Expo is scheduled for February 12–16, 2012, at the Tampa Convention Center in Tampa, Florida.