Publication Number: FHWA-HRT-07-004

Communication Product Updates

Compiled by Zac Ellis of FHWA's Office of Research and Technology Services

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:

Address requests for items available from:

For more information on research and technology publications 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.

SafetyAnalyst

Publication No. FHWA-HRT-06-124

SafetyAnalyst is a set of software tools currently under development to help State and local transportation agencies analyze the safety performance of specific locations, suggest appropriate countermeasures, quantify their expected benefits, and evaluate their effectiveness. SafetyAnalyst incorporates state-of-the-art approaches to managing safety that will guide the decisionmaking process by identifying needs and offering a systemwide program for improvements. SafetyAnalyst also will include economic analysis tools to ensure that transportation agencies achieve the greatest possible benefit from each dollar committed to improving highway safety.

The SafetyAnalyst toolkit will address site-specific physical modifications to the highway system but is not intended for general driver or vehicle programs developed to improve systemwide safety. The software will enable agencies to identify crash patterns at specific locations and determine whether crashes occur more frequently than expected. In addition, highway officials will be able to use SafetyAnalyst to review the frequency and percentage of particular crash types throughout the entire highway system or for particular roadway segments or intersections. Highway agencies also will be able to use SafetyAnalyst to investigate the potential benefits of engineering improvements at specific sites. FHWA expects to release the final tools in 2008.

This document is available online at www.fhwa.dot.gov/publications/research/safety/06124/index.cfm. Paper copies also are available from FHWA's R&T Product Distribution Center.

This TechBrief provides a summary of the computer software, Pedestrian and Bicycle Crash Analysis Tool (PBCAT) Version 2.0, which replaces PBCAT Version 1.0. FHWA designed the software to assist State and local officials, planners, and engineers in reducing crashes involving pedestrians and bicyclists. A handbook for the software, Pedestrian and Bicycle Crash Analysis Tool (PBCAT): Version 2.0 Application Manual (FHWA-HRT-06-089), also is available.

To download the software and manual, visit www.fhwa.dot.gov/research/tfhrc/, www.walkinginfo.org/pc/pbcat.cfm, or www.bicyclinginfo.org/bc/pbcat.cfm.

This study reports on the continued field evaluations of treatments applied to four pavements suffering from distress caused by alkali-silica reactions (ASR). Researchers evaluated one set of treatments on existing pavements that already showed ASR-related distress in California, Delaware, and Nevada. Two of the existing pavements are located in relatively dry environments, while the third (in Delaware) is located in a moderately wet environment. The fourth site, in New Mexico, consists of treatments on newly constructed pavements built with known reactive aggregates.

At the Nevada site, the researchers treated the pavement with methacrylate (HMM), silane, linseed oil, or lithium hydroxide. The Delaware site used only lithium hydroxide, while the California site used only methacrylate. The test sections in New Mexico consisted of pavement that contained admixtures as ASR inhibitors. The study involved three types of treatments, with variations within each type: (1) addition of lithium hydroxide (at two rates); (2) replacement of 25 percent of the cement with various combinations of Class C and Class F fly ash; and (3) addition of a high-range water reducer (HRWR).

The evaluation showed that none of the treatments was significantly beneficial to pavements with moderate to advanced ASR damage. The methacrylate sealer was effective when applied to a bridge deck, as it extended the pavement service life by 3 to 5 years or more when applied in two to three coats. The results indicate that, regardless of the treatment, upward moisture migration from the subgrade to the bottom of the pavement is sufficient to support continued ASR even in dry desert climates. Preliminary results from the New Mexico test sites show that Class F ash, Lomar (HRWR), or blended Class C and F ashes may improve resistance to ASR distress. However, Class C ash can make deterioration much worse. Careful selection of the fly ash is necessary when attempting to mitigate known reactive aggregates. The researchers recommended continued monitoring of this test site.

This document is available online at www.fhwa.dot.gov/pavement/pccp/pubs/02082. Limited copies are available from FHWA's R&T Product Distribution Center. The document also is available from NTIS under order number PB2006-114290.

Researchers constructed field test sections during 1992 as part of the SHRP investigation of the frost resistance of concrete. The first freeze-thaw-related deterioration the researchers expected to see on the pavement concrete after it was exposed to deicing salt was salt scaling. However, the test sections constructed in Ohio were diamond-ground between construction and the monitoring team's first visit. The diamond-ground surface did not deteriorate over time. The researchers determined that internal deterioration of the Ohio test sections was not present or, where present, was caused by a mechanism other than freeze-thaw. Further, the researchers did not detect freeze-thaw deterioration in the Minnesota test sections (not exposed to deicing salts), though freeze-thaw tests conducted on specimens cut from the test sections 6 years after construction showed significantly different performance than specimens prepared and tested at the time the test sections were constructed.

For both the Ohio and Minnesota sections, the researchers concluded that only 6 years of winter exposure would not be adequate to evaluate the potential long-term performance thoroughly. Though the Ohio sections have been overlaid, making further monitoring impossible, the Minnesota sections are still exposed. The researchers recommended additional monitoring of these sections, along with exposing sections to salt to determine their resistance to salt scaling. The D-cracking mitigation study indicated that in many cases the D-cracking returned after 6 years, independent of the mitigation technique tried. Additional testing would be required to make further evaluations.

This document is available online at www.fhwa.dot.gov/pavement/pccp/pubs/02083. Limited copies are available from FHWA's R&T Product Distribution Center. The document is also available from NTIS under order number PB2006-114291.

This research study, sponsored by FHWA, summarizes the field performance of high-early-strength (HES) concrete patches between 1994 and 1998. Researchers constructed the patches under SHRP between June 1991 and July 1992 in Arkansas, Illinois, Nebraska, New York, and North Carolina using existing State construction practices. The patches were constructed mainly with Type III cement, four types of coarse aggregate, and three types of fine aggregate. The researchers used similar types of air-entraining admixtures, water reducers, and set accelerators at all except the North Carolina site. The patches were located in areas with varying environmental and traffic conditions. The performance criterion of interest was durability. The researchers quantified the durability of the HES concrete over a period of 7 years using various indicators including compressive strength, static elastic modulus, rapid chloride permeability, and asphalt concrete (AC) impedance. Also, they visually examined the HES patches to locate any material- or durability-related distresses. This report discusses in detail the effects of climate and material properties on the durability of HES concrete.

Some of the results of interest include the effect of water reducer type, curing method, and aggregate type on long-term durability. The report also presents comparisons of the rapid chloride permeability and AC impedance test results and the rate of strength gain for the mixes evaluated. Overall, the HES patches performed well with no obvious signs of deterioration. However, the results were not conclusive because the performance monitoring period was relatively short. The researchers recognized a need for further research in the areas of mechanical properties and long-term durability of HES concrete.

This document is available online at www.fhwa.dot.gov/pavement/pccp/pubs/02084. Limited copies are available from FHWA's R&T Product Distribution Center. The document is also available from NTIS under order number PB2006-115204.

The objective of this study was to monitor and evaluate the performance of experimental full-depth repairs made with HES materials placed under SHRP Project C-206. Researchers conducted the experiment to demonstrate and validate technologies that would enable highway agencies to reopen full-depth portland cement concrete (PCC) pavements to traffic after repairs and document the information needed to apply this technology. The experimental factors for the study included material type, strength at opening, and repair length. The researchers evaluated a total of 11 HES concrete mixes with opening times ranging from 2-24 hours at two field sites (U.S. I-20, Augusta, GA, and State Route 2, Vermilion, OH).

The scope of the study included 5-year monitoring of SHRP C-206 full-depth sections, analyzing the data, and revising the guidelines for early opening of full-depth PCC pavement repairs as needed. The monitoring program consisted of visual surveys of distress to monitor the development of cracking, faulting, and spalling. The researchers conducted the surveys annually from the fall of 1994 through the fall of 1998. The results of the evaluation showed that full-depth repairs made with HES PCC can provide effective long-term performance; however, adverse temperature conditions during installation can cause premature failures. Extremely high PCC temperatures during curing also should be avoided. The study found that fatigue damage due to early opening is negligible, especially for repairs of 3.7 meters (12.14 feet) or shorter. Within the range of strength evaluated under SHRP C-206, the strength at opening could not be correlated to performance. Based on the results of this evaluation, the researchers recommended no changes to the opening criteria suggested in the SHRP C-206 manual of practice.

This document is available online at www.fhwa.dot.gov/pavement/pccp/pubs/02085. Limited copies are available from FHWA's R&T Product Distribution Center. The document is also available from NTIS under order number PB2006-114292.

Researchers installed and tested two types of concrete overlays — silica fume concrete (SFC) and latex-modified Type III PCC (LMC-III) — as part of SHRP Project C-206: Optimization of Highway Concrete Technology — Bridge Deck Overlays. The two overlay types were chosen for their ability to fill two needs. The researchers chose SFC as a long-term, low-permeability overlay, and they selected LMC-III as an HES concrete for use when traffic had to be restored after as little as 24 hours. This report summarizes the 5-year study to evaluate the long-term performance of the overlays.

The researchers evaluated and compared SFC and LMC-III overlays at four locations in Kentucky and Ohio. Installed in 1992, each test site included SFC and LMC-III overlays on opposite directions of a bridge structure. The study evaluated the overlays each year between 1994 and 1998. All overlays had high initial bond strengths that remained high over the study period when tested away from delamination. The researchers rated the overlays as in generally good condition in 1998, after 6 years of service, though some individual sites were rated as fair due to extensive cracking.

Though both SFC and LMC-III overlays performed satisfactorily, the service life of the overlays tended to vary based on the site location. Generally, cracking and delamination of the overlays tended to increase with time. Typically, all overlays should be inspected biannually for cracking, delamination, and routine maintenance, including consideration of crack and delamination repairs to extend the service life of SFC and LMC-III overlays.

This document is available online at www.fhwa.dot.gov/pavement/pccp/pubs/02086. Limited copies are available from FHWA's R&T Product Distribution Center. The document is also available from NTIS under order number PB2006-114293.