Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Product Distribution Center.

When ordering from NTIS, include the NTIS publication number (PB 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:

National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-605-6000
Toll-free number: 800-553-NTIS (6847)

Address requests for items available from:

Federal Highway Administration
R&T Product Distribution Center, HRTM-03
E-mail: report.center@dot.gov

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

May 2008 Focus Newsletter
Publication No. FHWA-HRT-08-013

The May 2008 issue of FHWA's Focus newsletter contains features on "National Work Zone Awareness Week 2008: Slow for the Cone Zone," "Rolling Wheel Deflectometer: A High-Speed Deflection Device to Improve Asset Management," "Advancing the Future of Long-Term Bridge Performance," and "New Course Introduces Strategies for Achieving More Effective Pavement Management Programs." This issue also includes an "In Brief" column on products and technologies for accelerating infrastructure innovations and a calendar of infrastructure-related events.

The May issue of Focus is available at www.fhwa.dot.gov/publications/focus/08may/index.cfm.

June 2008 Focus Newsletter
Publication No. FHWA-HRT-08-014

The June 2008 issue of FHWA's Focus newsletter features articles on the following topics: "Extending the Life of Roads and Bridges in Louisiana," "FHWA Offers Soil Nail Showcase," "Meet The Little Book of Quieter Pavements," and "FHWA Regional Conferences Showcase Asset Management Around the Country." The newsletter's highway technology calendar lists upcoming events related to products and technologies for accelerating infrastructure innovations.

The June issue of Focus is available at www.fhwa.dot.gov/publications/focus/08jun/index.cfm.

Development of a Driver Vehicle Module for the Interactive Highway Safety Design Model

Publication No. FHWA-HRT-08-019

FHWA is developing an integrated set of software tools to improve highway design, known as the Interactive Highway Safety Design Model (IHSDM). IHSDM is a suite of tools to help highway project planners, designers, and reviewers at State and local departments of transportation (DOTs) and engineering consulting firms evaluate the safety and operational effects of geometric design decisions on two-lane rural highways. The latest version released to the public includes the following components: (1) Policy Review Module, (2) Design Consistency Module, (3) Crash Prediction Module, (4) Traffic Analysis Module, and (5) Intersection Review Module. A sixth module, the Driver Vehicle Module (DVM), is a candidate for future release.

This report, Development of a Driver Vehicle Module for the Interactive Highway Safety Design Model, provides a complete technical discussion of the DVM. The report includes a description of the specification, verification, and calibration/validation of the DVM for the passenger vehicle and heavy vehicle components, along with additional functionality enhancements.

The report is available online at www.fhwa.dot.gov/publications/research/safety/08019/index.cfm and from NTIS under order number PB2008106477.

Methods for Maintaining Traffic Sign Retroreflectivity

Publication No. FHWA-HRT-08-026

In response to a congressional directive, FHWA established minimum retroreflectivity levels for traffic signs and incorporated them into the Manual on Uniform Traffic Control Devices (MUTCD). One of the concerns expressed by agency personnel responsible for conformance with required minimums is the potential increase in tort exposure. Therefore, FHWA developed methods for maintaining retroreflectivity that, when implemented as intended, provide agencies with a flexible means of conforming with required minimum retroreflectivity levels and offer protection from potential tort claims. After completing an engineering study, agencies also can use other methods to maintain signs at the required minimum retroreflectivity levels. The information in this report can help DOTs determine which retroreflectivity maintenance method or combination of methods best suits their needs.

The report is available from NTIS under order number PB2008106478.

Long Term Pavement Performance Computed Parameter: Moisture Content

Publication No. FHWA-HRT-08-035

FHWA researchers conducted a study to compute in situ soil parameters based on time domain reflectometry (TDR) traces obtained from Long Term Pavement Performance (LTPP) test sections instrumented for the seasonal monitoring program (SMP). The researchers installed 10 TDR sensors in the base and subgrade layers at each of the 70 SMP test sites monitored as part of the LTPP program.

The report provides a comprehensive description of a new method developed as part of the study to estimate moisture content, dry density, reflectivity, and conductivity of the soil from TDR traces. This new method utilizes transmission line equations and micromechanics models calibrated to site-specific conditions for each site/layer combination. The researchers also documented background information on existing empirical methodologies used to estimate subsurface moisture content from TDR traces. The researchers compared the results to previous methods as well as ground truth data to evaluate the new model's ability to predict soil parameters.

The researchers found that the transmission line equation and micromechanics method provides accurate results and used the method to interpret more than 270,000 TDR records stored in the LTPP database. A computer program, MicroMoist, aided in the computation of soil parameters based on TDR trace data and calibration information. The report provides details on the program, along with descriptions of the tables developed to store the computed values in the LTPP Information Management System database.

The report is available online at www.fhwa.dot.gov/pavement/ltpp/pubs/08035. Printed copies of this report are available from FHWA's R&T Product Distribution Center.

LTPP Year in Review 2007

Publication No. FHWA-HRT-08-039

Improving mobility on the highways is FHWA's mission. During 2007, FHWA's LTPP program worked toward this mission through its efforts to provide answers to how and why pavements perform as they do. To better understand pavement performance, the LTPP program gathers and processes data describing the structure, service conditions, and performance of 2,513 pavement test sections in North America. Highway engineers use these data and data analysis findings to help make decisions that lead to more cost-effective and better performing pavements.

In 1987, when FHWA initiated the LTPP program as a project of the 20-year Strategic Highway Research Program, the agency designed the LTPP program as a partnership. In 2007, the State and Canadian Provincial highway agencies, American Association of State Highway and Transportation Officials, Transportation Research Board, Canadian Strategic Highway Research Program, and FHWA continued to play key roles in helping the program achieve its goals. These partners stay informed about research results and program activities through the LTPP Web site, e-mail newsletter, publications, meetings and workshops, industry trade associations, and professional societies.

FHWA released this report to summarize activities undertaken by the LTPP program during the 2007 calendar year. The report is available at www.fhwa.dot.gov/pavement/ltpp/pubs/08039.

Surrogate Safety Assessment Model (SSAM) (TechBrief)

Publication No. FHWA-HRT-08-049

This TechBrief summarizes the research and development of the SSAM. The model combines microsimulation and automated conflict analysis to analyze the frequency and character of narrowly averted vehicle-to-vehicle collisions in traffic. The goal is to assess the safety of traffic facilities without waiting for a statistically above normal number of crashes and injuries to actually occur.

The TechBrief is available at www.fhwa.dot.gov/publications/research/safety/08049/index.cfm. Printed copies are available from FHWA's R&T Product Distribution Center.

Surrogate Safety Assessment Model (SSAM)—Software User Manual

Publication No. FHWA-HRT-08-050

This document is a user's manual for the SSAM software, providing guidance on installing and using the software to perform surrogate safety analyses of a traffic facility, such as a signalized intersection. The software processes vehicle trajectory data from a given microscopic traffic simulation to identify the frequency of conflicts—where two vehicles are on a collision course and one vehicle must make an evasive maneuver to avoid a collision. Such surrogate measures have been shown to correlate to some degree with the historical frequency of crashes at intersections. This technique may be of use to researchers, transportation engineers, construction and design companies, and safety engineers.

For more information regarding the SSAM application, including discussion of the theoretical background and the results of a series of evaluation tests, see the corresponding FHWA research report titled Surrogate Safety Assessment Model and Validation: Final Report (FHWA-HRT-08-051).

The manual is available at www.fhwa.dot.gov/publications/research/safety/08050/index.cfm. Copies also are available from NTIS under order number PB2008111196.

Surrogate Safety Assessment Model and Validation: Final Report

Publication No. FHWA-HRT-08-051

Researchers most often assess the safety of intersections, interchanges, and other traffic facilities by tracking and analyzing police-reported motor vehicle crashes over time. Given the infrequent and random nature of crashes, this process is slow to reveal the need for remediation of either the roadway design or the flow-control strategy. This process also is not applicable to assessing new designs that have yet to be built or assessing flow-control strategies before they are deployed onsite.

This document is a final report on research and development of an alternative safety assessment approach using conflict analysis—analyzing the frequency and character of narrowly averted vehicle-to-vehicle collisions—as a surrogate measure of actual crash data. Researchers developed a software prototype to automate conflict analysis of vehicle trajectory data, which now can be exported from the traffic simulation software of four vendors who collaborated on the project. The majority of the report describes testing conducted to evaluate the efficacy of this approach. The findings may be of interest to transportation engineers, safety engineers, researchers, simulation designers, and firms providing simulation or intersection design services.

The report is available at www.fhwa.dot.gov/publications/research/safety/08051/index.cfm. Copies also are available from NTIS under order number PB2008111797.

Innovator, Volume 2, Issue 7, June/July 2008

Publication No. FHWA-HIF-08-027

The Innovator newsletter, published monthly by FHWA's Highways for LIFE program, advances implementation of innovative technologies and processes in the highway industry. The June/July 2008 issue features the following articles: "Surveys Help DOTs Boost Customer Satisfaction," "Q&A with Kelly Damron: Transforming a DOT," "'Best Solutions' Workshop Resonates in North Carolina," "SPMTs Topic of NHI Seminar," "Virginia Projects Use Rapid Replacement to Slash Construction Time, Congestion," and "Precast Concrete Pavement Systems Speed Construction." Innovator's audience includes transportation professionals in highway agencies, trade and research groups, academia, the private sector, and the driving public.

The June/July 2008 issue of Innovator is available at www.fhwa.dot.gov/hfl/innovator/issue07.cfm.

July 2008 Focus Newsletter

Publication No. FHWA-HRT-08-015

The June 2008 issue of FHWA's Focus newsletter contains features on "Improving Pavement Performance With the Asphalt Mixture Performance Tester," "FHWA to Award Grants to Spur Highway Technology Innovation," "Pavement Recycling Technology Deployment: Meeting Today's Environmental and Economic Challenges," and "Ninth International Conference on Concrete Pavements: Tomorrow's Concrete Pavements Today." It also includes a calendar of infrastructure-related events.

The July issue of Focus is available at www.fhwa.dot.gov/publications/focus/08jul/index.cfm.