Below are brief descriptions of communications products recently developed by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. All of the reports are available or will be available soon from the National Technical Information Service (NTIS). In some cases, limited copies of the communications products are available from FHWA's Research and Technology (R&T) Product Distribution Center (PDC).

When ordering from NTIS, include the NTIS publication number and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:

Requests for items available from the R&T Product Distribution Center should be addressed to:

For more information on R&T communications products available from FHWA, visit FHWA's Web site at www.fhwa.dot.gov, the Turner-Fairbank Highway Research Center's Web site at www.tfhrc.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.

The Long-Term Pavement Performance (LTPP) program reached its 20-year pavement monitoring milestone in 2009. This report summarizes the current status of the LTPP program and its major activities--data collection, storage, and analysis, and product development. The report also describes the work needed beyond 2009 to capitalize on the investment made in developing the world's most comprehensive pavement research database, the LTPP program's most important product.

According to the report, the work that remains includes providing ongoing security and maintenance of the LTPP database and managing the Materials Reference Library, continuing to support LTPP database users, further developing and refining the database, and continuing data analysis and product development. These needs are included in FHWA's planning for future infrastructure research and development, and will help the transportation industry reap the full rewards of the program and continue to influence pavement design, building, and maintenance.

The report is available at www.fhwa.dot.gov/pavement/ltpp/pubs/09052/index.cfm. Printed copies are available from the PDC.

Most embankment and subgrade soils are best compacted statically using pad foot rollers, yet none of the intelligent compaction systems currently used measure stiffness or elastic modulus of the soil during static compaction. Estimating soil modulus is important because subgrade modulus is a key factor in pavement design and performance-based quality assurance.

In the study summarized in this fact sheet, researchers with FHWA's Exploratory Advanced Research (EAR) Program are developing a prototype system to continuously measure soil modulus through its relationship with the contact force-displacement response of individual roller pads. This document introduces the new approach to intelligent compaction, measuring of pad contact force and soil deflection, and future efforts of this EAR project.

According to the report, if accurate and reliable, such a system would be significantly superior to the current practice of spot testing. When the project concludes in 2010, the system will be nearly ready for commercial production, subject to individual roller manufacturer specifications.

The fact sheet is available at www.fhwa.dot.gov/advancedresearch/pubs/soilcompact.cfm. Printed copies are available from the PDC.

Metropolitan planning organizations face increasingly complex challenges in modeling interactions between the built environment and multimodal transportation systems. An EAR project launched in 2008 is addressing this issue. Titled Modeling the Urban Continuum in an Integrated Framework: Location Choice, Activity Travel Behavior, and Dynamic Traffic Patterns, the project's goal is to model land use, travel demand, and traffic flow in urban systems.

The project will create a conceptual framework, an integrated prototype, and computational tools for tailoring integrated systems using available microsimulation models. These models cover a broad array of decisions and behaviors by individuals, businesses, and governments, from long-term location choices to daily travel route choices. FHWA researchers expect that the innovations achieved through this project will have a major impact on transportation planning for a sustainable future.

The entire set of research products--source code, graphical user interfaces, programs and scripts, architecture documentation, and user guides--will be available on the FHWA Web site in 2011.

This fact sheet addresses the microsimulation of urban systems, key challenges to integrated modeling, project progress, and future efforts. The fact sheet is available at www.fhwa.dot.gov/advancedresearch/pubs/interurbsys.cfm. Printed copies are available from the PDC.

The ability to modulate the speed and spacing of individual vehicles in relation to unseen events farther downstream has the potential to keep traffic flowing smoothly, safely, and at optimum density. Toward this end, FHWA researchers are modeling, testing, and demonstrating prototype systems in three areas: (1) improving traffic flow by calculating and communicating speed guidance directly to individual drivers; (2) achieving closer coordination, shorter vehicle separation gaps, and higher effective lane capacities through vehicle-vehicle communication, vehicle-infrastructure communication, and cooperative adaptive cruise control; and (3) improving fuel efficiency of heavy trucks and doubling the capacity of truck-only lanes by forming and maneuvering automated three-truck platoons, which use short following headways to increase fuel efficiency through aerodynamic effects and use less road space.

An EAR project launched by FHWA in 2007, Develop-ment and Evaluation of Selected Mobility Applications for VII (vehicle-infrastructure integration), focuses on how to use the new capabilities of intelligent vehicles and highway infrastructure to reduce congestion and increase highway capacity. According to a project report, the project will determine whether these next-generation solutions are feasible and, if so, what further work needs to be done to move them toward deployment.

This fact sheet describes capitalizing on the potential of intelligent vehicles and infrastructure to manage traffic speed, flow, and density to achieve greater efficiency, and outlines future efforts for this EAR project. The fact sheet is available at www.fhwa.dot.gov/advancedresearch/pubs/inchwyfact.cfm. Printed copies are available from the PDC.

As part of its strategic highway safety plan support effort, FHWA organized 26 States to participate in the FHWA evaluation of the Low Cost Safety Improvements Pooled Fund Study. The purpose of this pooled study is to estimate the safety effectiveness of several unproven, low-cost safety strategies identified in the National Cooperative Highway Research Program Report 500 series.

This report, Safety Evaluation of Offset Improvements or Left-Turn Lanes, examines the safety effectiveness of offset improvements for left-turn lanes at signalized intersections. The purpose of this strategy is to reduce the frequency of crashes by providing better visibility for drivers who are turning left at signalized intersections. The strategy's safety effectiveness has not been documented thoroughly, so this study attempts to provide a crash-based evaluation through scientifically rigorous procedures, such as data collection and analysis from several States that have implemented offset improvements for left-turn lanes at signalized intersections.

The general conclusion from this research is that positive offset improvements for left-turn lanes (that is, when left-turn lanes are shifted left to enhance sight distance for opposing left-turn drivers) have the potential to reduce the total number of crashes and crash severity at signalized intersections. Therefore, the researchers conclude that the use of positive offset improvements for left-turn lanes is justified as a safety improvement, particularly at intersections where nine or more crashes are expected per year. The report provides crash reduction factors and benefit-cost ratios for nation--wide safety applications.

The report is available at https://www.fhwa.dot.gov/publications/research/safety/09036/index.cfm. Printed copies are available from the PDC.