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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - July/August 2011

July/August 2011
Issue No:
Vol. 75 No. 1
Publication Number:
Table of Contents

Communication Product Updates

Communication Product Updates

by Zachary Ellis of FHWA's Office of Corporate Research, Technology, and Innovation Management

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 or will soon be available 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 (PB number) and the publication title. You also may visit the NTIS Web site at 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
5301 Shawnee Road
Alexandria, VA 22312
Telephone: 703–605–6000
Toll-free number: 800–553–NTIS (6847)
Web site:

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

R&T Product Distribution Center
Szanca Solutions/FHWA PDC
13710 Dunnings Highway
Claysburg, PA 16625
Telephone: 814–239–1160
Fax: 814–239–2156

For more information on R&T communications products available from FHWA, visit FHWA’s Web site at

Finite Element Analysis of UHPC: Structural Performance of an AASHTO Type II Girder And a 2nd-Generation Pi-Girder (TechBrief)

Publication No. FHWA-HRT-10-079

Front page of Finite Element Analysis of UHPC: Structural Performance of an AASHTO Type II Girder and a 2nd-Generation Pi-Girder (TechBrief).UHPC is an advanced cementitious composite material that exhibits exceptional durability, increased strength, and long-term stability. FHWA conducted a research program aimed at developing general modeling concepts within a commercially available software package to facilitate the development of UHPC structural systems including bridges. This TechBrief highlights the research techniques and the results of the program.

The research focused on calibrating the proposed finite element models to a series of completed full-scale structural tests on existing UHPC structural components, including a prestressed UHPC American Association of State Highway and Transportation Officials (AASHTO) Type II girder and prestressed UHPC second-generation pi-girder. Researchers found the proposed modeling techniques to be effective.

The document is available at Printed copies are available from the PDC.

Long-Term Pavement Performance Program: Accomplishments and Benefits 1989-2009

Publication No. FHWA-HRT-10-071

Cover of Long-Term Pavement Performance Program: Accomplishments and Benefits 1989-2009.The need for information on how pavements perform over time became a critical issue for highway agencies in the early 1980s, when roads built two or three decades earlier started to show clear signs of deterioration. The Long-Term Pavement Performance (LTPP) program started in 1987 as part of the Strategic Highway Research Program (SHRP), and continued under FHWA when the SHRP ended in 1992. This report highlights what researchers have learned to date, discusses innovations and new products generated under the program, outlines LTPP's critical role in pavement design, and points to the future of the LTPP program.

Since 1989, the LTPP program has monitored nearly 2,500 pavement test sections throughout the United States and Canada. Approximately 950 test sections are still being monitored today. By collecting and analyzing data from these pavement test sections over time, researchers are gaining insights on how and why pavements perform as they do — learning how to build better, longer lasting, and more cost-effective pavements.

The LTPP program has generated a wide range of benefits across the spectrum of pavement engineering and performance. The benefits and products from the LTPP program fit into three categories: the LTPP database, advances in pavement performance measurement, and contributions to pavement design and management. The LTPP database is the single largest benefit from the program, providing reliable pavement performance data for thousands of requestors throughout the academic community and the public and private sectors. The database is the foundation for fundamental and applied research, and the nucleus for advancements in pavement design and management processes.

The document is available at A summary of the full report (FHWA-HRT-10-072) is available at Printed copies of both publications are available from the LTPP Customer Support Service Center at 202-493-3035 or

LTPP Computed Parameter: Dynamic Modulus (TechBrief)

Publication No. FHWA-HRT-11-018

Front page of LTPP Computed Parameter: Dynamic Modulus (TechBrief).The dynamic modulus, |E*|, is a fundamental property of asphalt concrete mixtures that defines strain response characteristics as a function of loading rate and temperature. The primary objective of this project, completed under FHWA's LTPP program, was to develop estimates of the dynamic modulus of hot-mix asphalt layers on LTPP test sections following the models used in the Mechanistic-Empirical Pavement Design Guide. This TechBrief provides a technical summary of the project including an introduction and explanations of the objective and application.

The significance of |E*| is threefold. First, it is one of the primary material property inputs in the Mechanistic-Empirical Pavement Design Guide and software developed by the National Cooperative Highway Research Program. Second, |E*| is one of the primary properties measured in the asphalt mixture performance test protocol that complements volumetric mix design with mechanical properties. Third, |E*| is one of the fundamental linear viscoelastic material properties that pavement designers can use in advanced pavement response models based on viscoelasticity.

Given the significance of |E*|, populating the LTPP database provides a valuable data source for the pavement community. Supplementing the full suite of material properties, performance history, and traffic and climate data with |E*| estimates is advantageous in conducting Mechanistic-Empirical Pavement Design Guide calibration, validation, and implementation. As a result of this study, more than 1,000 layers in the LTPP database now have |E*| estimate information available.

The document is available at Printed copies are available from the PDC.

LTPP Pavement Performance Forecast (Product Brief)

Publication No. FHWA-HRT-10-080

Developed as part of the Transportation Pooled Fund study "Effect of Multiple Freeze Cycles and Deep Frost Penetration on Pavement Performance," TPF-5(013), the LTPP Performance Forecast produces freeze and thaw performance predictions for both rigid and flexible pavements. This Product Brief introduces the product, discusses its application and use, and provides an example.

State, county, and local highway agencies can use the LTPP Performance Forecast to estimate performance trends for pavement sections of interest in specific user-defined environmental settings. Using the LTPP Performance Forecast, researchers can compute roughness, structural cracking, environmental cracking, rutting, and faulting predictions as a function of pavement age. The forecasts are based on user-defined inputs such as traffic, structural, environmental, and subgrade conditions.

Because the study's main objective was to quantify the impacts of frost on pavement performance, the model covers both frost and nonfrost regions and is applicable to a range of climates. The online component is available at

The brief is available at Printed copies are available from the PDC.