U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: Date: September/October 2001|
Issue No: Vol. 65 No. 2
Date: September/October 2001
Below are brief descriptions of reports recently published by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. All of the publications are available from the National Technical Information Service (NTIS). In some cases, limited copies of the publication are available from the Research and Technology (R&T) Report Center.
When ordering from NTIS, include the NTIS PB number (or publication number) and the publication title. You may also 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)
Expanded Sales Desk Hours: 8 a.m. to 8 p.m. EST, Mon.-Fri.
Requests for items available from the R&T Report Center should be addressed to:
R&T Report Center, HRTS-03
Federal Highway Administration
9701 Philadelphia Court, Unit Q
Lanham, MD 20706
Telephone: (301) 577-0906
Fax: (301) 577-1421
For more information on research and technology publications coming from FHWA, visit the Turner-Fairbank Highway Research Center's (TFHRC) Web site at www.fhwa.dot.gov/research/tfhrc/, FHWA's Web site at www.fhwa.dot.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov/.
Highway Bridge Inspection: State-of-the-Practice Survey
Publication No. FHWA-RD-01-033
A survey was conducted to help determine current policies and practices that may affect the accuracy and reliability of visual inspection. The survey had three main objectives. The first objective was to compile a state-of-the-practice report for bridge inspection, particularly as it pertains to visual inspection. The second objective was to gather information on bridge inspection management to study how inspection management may influence the reliability of inspections. The final objective was to gather data about the current use of nondestructive evaluation technologies and to identify current and future research needs.
Participants included State departments of transportation (DOTs), as well as some local-level DOTs (the 99 Iowa counties) and select bridge inspection contractors. Results from the questionnaires are presented in a question-by-question format. The motivation behind each question and the response percentages for each question start the discussion, followed by the results obtained. Included within each question are comments that will highlight the results.
The NTIS publication number is PB2001-107339.
Characterization of Transverse Profiles
Publication No. FHWA-RD-01-024
A study of the transverse profile data currently being collected under the Long Term Pavement Performance project was undertaken. The data were collected by three processes: (1) Dipstick®, (2) a photographic method, and (3) a straightedge used to collect rut depths.
This study examined several indices for the purposes of quantifying and qualifying the transverse profiles. It is recommended that five indices be added to the National Information Management System. These indices include the area of the rut below a straight line connecting the end points of the transverse profile, the total area below the straight lines connecting the maximum surface elevations, the maximum depth for each wheelpath between a 1.8-m straightedge placed across the wheelpath and the surface of the pavement, and the width of the rut based on a 1.8-m straightedge.
These indices were studied to determine typical trends by climate, surface thickness, soil type, and age. In addition, the time-series trends for each test section were studied to determine whether any anomalies existed and the potential causes of these anomalies.
The NTIS publication number is PB2001-105685.
Reliability of Visual Inspection for Highway Bridges
Volume I: Final Report and Volume II: Appendices
Publication Nos. FHWA-RD-01-020 and -021
Visual inspection is the predominant nondestructive evaluation technique used in bridge inspections. However, since implementation of the National Bridge Inspection Standards in 1971, a comprehensive study of the reliability of visual inspection as it relates to highway bridge inspections has not been conducted. The goals of the study include providing overall measures of the accuracy and reliability of Routine and In-Depth Visual Inspections, studying the influence of several key factors that affect Routine and In-Depth Inspections, and studying the differences between State inspection procedures and reports.
Ten inspection tasks were performed at seven test bridges using State bridge inspectors. The sample of participating inspectors included 49 inspectors from 25 State agencies. Inspectors were provided with common information, instruction, and tools. Inspector characteristics were measured through self-report questionnaires, interviews, and direct measurements.
Routine inspections were completed with significant variability, and the Condition Ratings assigned varied over a range of up to five different ratings. It is predicted that only 68 percent of the Condition Ratings will vary within one rating point of the average, and 95 percent will vary within two points. Factors that appeared to correlate with Routine Inspection results include Fear of Traffic; Visual Acuity and Color Vision; Light Intensity; Inspector Rushed Level; and Perceptions of Maintenance, Complexity, and Accessibility.
The NTIS publication numbers are PB2001-107603 (Volume I) and PB2001-107599 (Volume II).
Performance Test for Geosynthetic-Reinforced Soil Including Effects of Preloading
Publication No. FHWA-RD-01-018
A study was undertaken to investigate the behavior of Geosynthetic-Reinforced Soil (GRS) masses under various loading conditions and to develop a simplified analytical model for predicting deformation characteristics of a generic GRS mass. Significant emphasis was placed on the effects of preloading. To conduct the study, a revised laboratory test, known as the Soil-Geosynthetic Performance (SGP) test, was developed. The test is capable of investigating the behavior of a generic GRS mass in a manner mimicking the field placement condition, and soil and geosynthetic reinforcement are allowed to deform in an interactive manner.
A series of SGP tests were performed. Different soils and reinforcements were employed, and the soil-geosynthetic composites were subject to various loading sequences. Correlations between the results of SGP tests and full-scale GRS structures were evaluated. It was found that the degree of reduction in settlement due to preloading could be assessed by the SGP tests with very good accuracy. Finite element analyses were performed to examine the stress distribution in the SGP test. The importance of using small reinforcement spacing was evidenced by the stress distribution. A Simplified Preloading-Reloading (SPR) analytical model was developed to predict the deformation characteristics of a GRS mass subject to monotonic loading and preloading/reloading. The SPR model was shown to be able to accurately predict the results obtained from the SGP tests and numerical analysis of automated plane strain reinforcement tests.
The NTIS publication number is PB2001-107602.
Long-Term Durability of Geosynthetics Based on Exhumed Samples From Construction Projects
Publication No. FHWA-RD-00-157
This report presents the results of mechanical and chemical tests on 24 retrieved geosynthetics from 12 sites across the United States and provides a baseline databank of the mechanical and chemical properties of many commonly used geosynthetics in transportation applications as tested by industry. It also provides a summary and synthesis of the results and methods from site retrievals and comments on the significance of laboratory index testing in developing durability design protocols. This report is the last report of a comprehensive study on the "Durability of Geosynthetic Materials for Highway Applications." Previously published reports include:
FHWA-RD-97-142, Stress Cracking Potential for HDPE Geogrids (NTIS No. PB99-105512).
FHWA-RD-97-143, Testing Protocols for Confined Creep and Extension Testing of Geosynthetics (NTIS No. PB98-138688).
FHWA-RD-97-144, Testing Protocols for Oxidation and Hydrolysis of Geosynthetics (NTIS No. PB99-157976).
The NTIS publication number is PB2001-105580.