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Publication Number:  FHWA-HRT-06-001 Vol. 69 No. 3    Date:  November/December 2005
Publication Number: FHWA-HRT-06-001 Vol. 69 No. 3
Date: November/December 2005


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:

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 the R&T Product Distribution Center to:

R&T Product Distribution Center, HRTS-03

Federal Highway Administration

9701 Philadelphia Court, Unit Q

Lanham, MD 20706

Telephone: 301–577–0818

Fax: 301–577–1421

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.

Safety Evaluation of Red-Light Cameras Publication No. FHWA–HRT–05–048

The objective of this final study was to determine the effectiveness of red-light-camera (RLC) systems in reducing crashes. RLC systems enhance accountability and enforcement for red-light running violations. Using the empirical Bayes (EB) research method, the study compared statistics drawn from test sites both before and after the implementation of RLC technology. Drawing from tests conducted in seven jurisdictions across the United States and from 132 sites, the study estimated the crash-reducing effects and associated economic effects of RLC systems and specifically derived costs for rear-end and right-angle crashes for various crash severity levels.

Cover of Publication: Safety Evaluations of Red-Light Cameras

The crash effects detected were consistent with those found in many previous RLC studies. Specifically, the RLC systems decreased right-angle crashes and increased rear-end ones. But further economic analysis, which examined the extent to which increased rear-end crashes might negate the benefit of fewer right-angle crashes, showed an aggregate benefit from RLC systems in terms of crash costs. A disaggregate analysis found that the greatest economic benefits can be attained at intersections with the following characteristics: high levels of average annual daily traffic, more right-angle than rear-end crashes, and the presence of protected left-turn phases.

The NTIS publication order number for this report is PB2005106539. To view this publication online, visit www.fhwa.dot.gov/publications/research/safety/05048/index.cfm.

Covered Bridge Manual

Publication No. FHWA–HRT–04–098

FHWA's Covered Bridge Manual provides guidance to transportation specialists involved with any aspect of maintaining covered bridges, from initial inspections and evaluations through engineering, rehabilitation, and construction. To provide users with introductory background information, the publication also contains general terminology for covered bridges as well as brief historical information. The manual covers loading, structural analysis, connections, and design issues. The last six chapters contain discussions of evaluation, maintenance, strengthening, and preservation of existing covered bridges; historic considerations; and a state-of-the-art guide on wood preservatives for covered bridges, including historic preservation requirements as directed by the U.S. Department of the Interior.

The appendices include an extensive series of case studies that highlight engineering problems and solutions for several covered bridges in the United States. A unique feature of the Covered Bridge Manual is that it focuses on nuances of how covered bridges are engineered, including some issues not addressed currently by national bridge specifications. The chapter on timber connections in particular provides a comprehensive discussion of joinery and represents an important contribution to covered bridge engineering.

To learn about the preservation of U.S. covered bridges, visit the Web site for the National Historic Covered Bridge Preservation Program at www.fhwa.dot.gov/bridge/covered.htm.

Estimating Cumulative Traffic Loads, Volume II: Traffic Data Assessment and Axle Load Projection for the Sites with Acceptable Axle Weight Data, Final Report for Phase 2

Publication No. FHWA–RD–03–094

This report contains findings of the second phase of a study to estimate traffic loads on long-term pavement performance (LTPP) sites. The first phase, which encompassed the development of an estimation methodology with numerical examples, now is documented in Estimating Cumulative Traffic Loads, Final Report for Phase 1 (FHWA-RD-00-054), first issued in July 2000. Phase 2 includes the assessment of the overall quality of traffic data for all 890 LTPP traffic sites surveyed and the projection of axle loads for each site that provided adequate traffic data. The Phase 2 report also includes the distribution of comprehensive traffic data reports to participating agencies and the incorporation of each agency's comments regarding the study's traffic projections.

The study developed projections for axle loads for all inservice years up to 1998 for LTPP traffic sites that had adequate traffic monitoring data in FHWA's Information Management System (IMS) database. The researchers expressed the projections as annual axle load spectra for single, tandem, and triple axles and placed the data into IMS-computed parameter tables. Appendix A summarizes projection results for all LTPP sites.

Cover of Estimating Cumulative Traffic Loads, Volume II: Traffic Data Assessment and Axle Load Projection for the Sites with Acceptable Axle Weight Data, Final Report for Phase 2

To overcome the difficulty of estimating traffic loads for the 332 LTPP sites without adequate data, researchers proposed developing an LTPP Pavement Loading Guide (PLG). Therefore, the report contains a description of the purpose, design parameters, and functionality of the PLG; a blueprint for the guide's development; and two examples of using the PLG to obtain traffic load projections for LTPP sites without site-specific data on truck class or axle load.

The recommended traffic analysis activities include the development of the PLG, completion of traffic load projections for all LTPP sites, and the development of a comprehensive action plan to better utilize existing traffic data. Recommended components of the action plan include a comprehensive quality assurance process, use of monthly traffic data for estimating traffic loads, and regional modeling using both LTPP and other traffic data.

The NTIS publication order number for this report is PB2005103114. To view the publication online, visit www.fhwa.dot.gov/pavement/ltpp/03094/03094.pdf.




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