Below are brief descriptions of communications products recently developed by the Federal Highway Administration’s 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 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
5301 Shawnee Road
Alexandria, VA 22312
Telephone: 703–605–6050
Toll-free number: 1–888–584–8332 
Web site: www.ntis.gov
Email: customerservice@ntis.gov

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

R&T Product Distribution Center
Szanca Solutions/FHWA PDC
700 North 3rd Avenue
Altoona, PA 16601
Telephone: 814–239–1160
Fax: 814–239–2156
Email: report.center@dot.gov 

For more information on R&T communications products available from FHWA, visit FHWA’s Web site at www.fhwa.dot.gov, the FHWA Research Library at www.fhwa.dot.gov/research/library (or email fhwalibrary@dot.gov), or the National Transportation Library at ntl.bts.gov (or email library@dot.gov).

Analysis of Cracking in Jointed Plain Concrete Pavements (Summary Report)

Publication Number: FHWA-HRT-16-073

Premature cracking can severely degrade concrete pavement structures. Many studies have suggested that premature longitudinal cracking is caused primarily by improper construction or rehabilitation practices combined with heavy load repetitions.

This summary report discusses an investigation of the trends of longitudinal and transverse cracking in jointed concrete pavements based on data from the Long-Term Pavement Performance (LTPP) program’s Strategic Study of Structural Factors for Rigid Pavements (SPS-2). LTPP SPS-2 is an excellent resource for studying long-term performance of jointed concrete pavements because of the availability of data for pavement performance, material properties, and environmental and traffic conditions.

Researchers identified the effects of slab properties, base type, traffic volume, and environmental factors on the occurrence and extent of longitudinal and transverse cracking from a simple analysis of the raw cracking data. They selected SPS-2 sites in Arizona and Arkansas to investigate cracking mechanisms in detail, proposed a new hypothesis for the prevalence of premature cracking on these sites, and tested the hypothesis using numerical simulations.

The researchers found that longitudinal and transverse cracking were more sensitive to slab thickness and base type than other construction variables. Surface cracking was worse in dry climatic zones than wet zones. Most transverse cracks initiated from the slab edge close to the shoulder, and two forms of longitudinal cracks can initiate from transverse edges of slabs: a single long crack or multiple short cracks along the whole section. In addition to inadequate compaction of the base layers during construction and rehabilitation, the major contribution to premature longitudinal cracking appeared to be voiding, or a lack of support underneath the entire length of the pavement, beneath the outer edge of the pavement. Voiding is caused by localized deformation of “depressurized” soil, which occurs principally because of slab curl, when the pavement curls upward or downward at the edges.

This document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/16073/index.cfm.

Optimization of Rib-to-Deck Welds for Steel Orthotropic Bridge Decks (Report)

Publication Number: FHWA-HRT-17-020

Highway agencies have used orthotropic steel decks for decades, especially on long-span bridges, because of their light weight and fast construction. However, fatigue cracking has been a maintenance nuisance because the geometries and direct wheel loading of these bridges create complex stresses that are difficult to predict using conventional design tools.

This report documents the results of fatigue testing of full-scale geometries of various orthotropic rib-to-deck welds. FHWA undertook this study to assess these weld geometries and potentially provide performance data that might alleviate restrictive specifications on fabrication. Currently, these restrictions reduce the competitiveness of orthotropic steel decks compared to other alternatives.

Researchers explored variables such as the welding process and weld penetration. When the project began, the common practice in the United States was to use a one-sided, partial-penetration weld joining the rib and deck plates together, with a minimum requirement of 80-percent penetration. Restrictive requirements such as these result in a very narrowly defined welding procedure with little tolerance for variation. In practice, this leads to numerous weld repairs and rigorous inspection requirements that drive up the cost of orthotropic deck fabrication. Researchers found that the 80-percent penetration requirement could be significantly relaxed because fatigue performance was dictated largely by weld size and not by penetration.

This report is expected to benefit those interested in the design and fabrication of steel orthotropic bridge decks, including State transportation departments, steel bridge fabricators, design consultants, and researchers.

This document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/structures/bridge/17020/index.cfm.

State of the Practice for Shoulder and Center Line Rumble Strip Implementation On Non-Freeway Facilities (Report)

Publication Number: FHWA-HRT-17-026

The overall goal of FHWA’s Roadway Departure Safety Program is to improve the safety of the Nation’s highways through the reduction of roadway departure crashes. Roadway departures continue to account for more than half of U.S. roadway fatalities annually and nearly 40 percent of serious injuries, making such crashes a significant safety concern.

This report discusses research aimed at providing agencies with a framework for making decisions on how to implement rumble strips. It includes a literature review detailing research related to rumble strip design, noise and vibration testing methods and findings, impacts on bicyclists and motorcyclists, pavement condition impacts, pavement marking visibility, operational effectiveness, and safety effectiveness.

The report also provides a review of current practices. These include department policies and standard drawings for rumble strip implementation strategies, systematic installation criteria, currently used rumble strip dimensions, high-crash corridor installation practices, and special considerations and modifications.

Researchers conducted a gap analysis based on the literature and current practices reviews. The analysis identified that transportation agencies struggle with the optimal design and location of rumble strips given the geometry and context of the roadway. Also, agencies face challenges in identifying when noise issues will be a concern and determining the optimal soundlevel.

In addition, to date, no research studies have explored the impacts of rumble strips on pedestrian or bicyclist safety. Little quantitative research exists on the impacts of rumble strips on pavements or longitudinal joints. Moreover, few safety studies have reported the dimensions of rumble strips included in the research. This lack of data makes it difficult to identify the safety effectiveness of different designs, particularly narrower and shallower rumble strips.

This report is intended for safety engineers, highway designers, planners, and practitioners at State and local agencies involved with decision making related to rumble strips.

This document is available to download at www.fhwa.dot.gov/publications/research/safety/17026/index.cfm.