Roundabouts have seen unprecedented growth across the United States, from just a handful a decade ago to more than 2,000 and counting. National guidance had to keep pace with the needs of states and communities planning and implementing roundabouts, and NCHRP took a lead role.

In regions across the nation, bridge engineers know that the next major seismic event is coming—maybe tomorrow, maybe centuries from now. DOTs have the critical charge of designing for earthquakes and protecting the lives of travelers.

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2262 contains 23 papers that explore spacing between freeway ramps, three-dimensional alignment, sight distance, design consistency for two-lane highways, passing process on two-lane rural highways, reduced-conflict intersections, operational interactions between freeway managed lanes and parallel, general p...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 181: Evaluation of Bridge-Scour Research: Abutment and Contraction Scour Processes and Prediction examines bridge-abutment scour and the effectiveness of the leading methods used for estimating design scour depth.

The Water Science and Technology Board, part of the National Academies’ Division on Earth and Life Studies (DELS), has released a report based on the proceedings of a workshop that examines whether floods and droughts are becoming more prominent in the United States, how they are changing at the regional scale, and what is known about global climate’s influence on these changes. This report pre...

TRB’s National Cooperative Highway Research Program (NCHRP) Report 696: Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content provides potential specifications for corrugated drainage pipe manufactured with recycled high-density polyethylene (HDPE). The report includes proposed draft specifications for recycled HDPE, formulations of virgin and recycled HDPE, and drainag...

TRB Transportation Research E-Circular E-C152: Adapting Transportation to the Impacts of Climate Change: State of the Practice 2011 focuses on transportation adaptation practices that can be implemented to yield potential benefits now and in the longer term. The document highlights what climate change adaptation means for the transportation industry. E-C152 was produced under the auspices ...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 177: Evaluation of Bridge Scour Research: Geomorphic Processes and Predictions explores the impact of long-term aggradation and degradation, and lateral river channel migration, on highway structures.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 175: Evaluation of Bridge Scour Research: Pier Scour Processes and Predictions explores the current state of knowledge regarding bridge-pier scour, assesses several methods for design estimates of scour depth, examines a structured methodology for scour-depth estimation for design purposes, and highlights aspects of&n...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2195 contains 18 papers that explore risk-based design, low-volume roads cross-section design, truck acceleration speeds at weigh stations, urban clear zone distance, passing sight distance, rural expressway intersection design guidance, the effects of freeway design elements on safety, and lengths of left-t...

Travelers in the United States rely on more than one-half million bridges to traverse valleys, bodies of water, roads, railroad tracks, and other physical obstacles. Standard practice requires that bridge foundations be designed to withstand the effects of sediment erosion around the piers or scour for 100 years of flow. Underestimating the impacts of scour can lead to bridge failure, while ove...

TRB’s National Cooperative Highway Research Program (NCHRP) Report 682: Scour at Wide Piers and Long Skewed Piers explores recommendations for a predictive equation for equilibrium local scour and a potential equation for predicting scour evolution rates at wide piers and skewed piers. The equations are designed to help provide better estimates of local scour and scour evolution rates than thos...

TRB Transportation Research Record: Journal of the Transportation Research Board, No. 2201 consists of 18 papers that explore bridge scour, nondestructive evaluation of bridges, bridge culverts and soil stabilization and analysis, bridge engineering case studies, and bridge structural health monitoring.

TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 347: A National Database of Subgrade Soil-Water Characteristic Curves and Selected Soil Properties for Use with the MEPDG explores the creation of a national database of pedologic soil families that contains the soil properties for subgrade materials needed as input to the Mechanistic-Empirical Pavement Design G...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 153: A National Database of Subgrade Soil-Water Characteristic Curves and Selected Soil Properties for Use with the MEPDG is the contractor’s final report and Appendices A through D related to NCHRP Research Results Digest 347 with the same title.  NCHRP RRD 347 explores the creation of a national database o...

TRB’s Airport Cooperative Research Program (ACRP) Web-Only Document 8: Alternative Aircraft Anti-Icing Formulations with Reduced Aquatic Toxicity and Biochemical Oxygen Demand explores the aquatic toxicity and biological oxygen demand state of the art, components, and promising alternative formulations of deicing and anti-icing products. The report also examines the performance; efficiency; mat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 148: Debris Photographic Archive and Supplemental Materials for NCHRP Report 653 includes the debris photographic archive, the survey questionnaire and list of respondents, and the report on the field pilot study related to development of NCHRP 653. NCHRP Report 653 : Effects of Debris on Bridge Pier Scour explores gu...

TRB’s National Cooperative Highway Research Program (NCHRP) Report 653: Effects of Debris on Bridge Pier Scour explores guidelines to help estimate the quantity of accumulated, flow event debris, based on the density and type of woody vegetation and river bank condition upstream and analytical procedures to quantify the effects of resulting debris-induced scour on bridge piers. The debris photo...

The Board on Atmospheric Sciences and Climate, part of the National Academies' Division on Earth and Life Studies (DELS), has released a report that examines the impacts of climate change and how the United States can begin adapting to them in beneficial ways. The report explores activities under way at state and local levels, adaptation options, and how the nation can become better prepared to...

TRB’s Airport Cooperative Research Program (ACRP) Research Results Digest 9: Alternative Aircraft and Pavement Deicers and Anti-Icing Formulations with Improved Environmental Characteristics explores the aquatic toxicity and biological oxygen demand state of the art, components, and promising alternative formulations of deicing and anti-icing products. The report also examines the performance; ...

TRB’s National Cooperative Highway Research Program (NCHRP) Report 396: Monitoring Scour Critical Bridges explores the current state of practice for fixed scour bridge monitoring.

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2101 includes 13 papers that explore rural low-volume roads issues, including objective distress measures for evaluating unpaved road condition, estimating roughness of unpaved roads, and assessing heavy traffic impacts on gravel roads. This issue of the TRR also examines the three-point imaging test for the...

TRB’s second Strategic Highway Research Program (SHRP 2) has released its 2008 Annual Report that summarizes progress made in 2008 in building the framework and platforms needed to fulfill the SHRP 2 vision: a highway system that actively contributes to improved quality of life for all Americans by providing safe, efficient mobility in an economically, socially, and environmentally responsible ...

TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 334: Joint Workshop on Abutment Scour: Present Knowledge and Future Needs – June 2008 explores the state of knowledge on bridge abutment scour.

TRB’s National Cooperative Highway Research Program (NCHRP) Report 611: Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments explores analytical and design methods for the seismic design of retaining walls, buried structures, slopes, and embankments.  The Final Report is organized into two volumes. NCHRP Report 611 is Volume 1 of this study. Volume 2 ,...

TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 382: Estimating Stiffness of Subgrade and Unbound Materials for Pavement Design explores the significance of the resilient modulus property, various methods of determining this property of subsoils and unbound bases, and the application of this parameter in the mechanistic-empirical pavement design guide.

TRB's Transportation Research Record: Journal of the Transportation Research Board, No. 2059 includes 11 papers that explore the Micro-Deval test for coarse aggregates, the Micro-Deval test for fine aggregates, anisotropic behavior of aggregate bases, permanent deformation of natural bituminous sands, stiffness of unbound aggregate bases, and shear strength of recycled glass.  This issue ...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2053 includes 9 papers that explore frost and thaw depth predictors for variable load restrictions, climate change impact on low-volume roads, sensor technology for spring load restrictions, fly ash with calcium chloride for stabilization of base and subgrade courses, and time domain reflectometry and micro...

TRB’s Transportation Research Circular E-C130: Geophysical Methods Commonly Employed for Geotechnical Site Characterization explores how geotechnical, geophysical tools are used to image or characterize the shallow subsurface of the Earth, typically to depths of less than several hundred feet.

TRB’s Transportation Research Circular E-C129: Use of Inclinometers for Geotechnical Instrumentation on Transportation Projects explores the state of the practice and representative applications on the use of inclinometer systems for measuring ground deformation and performance of geotechnical design elements on transportation projects. The report examines inclinometer components and installat...