TRB has released Critical Issues in Transportation 2019 . In this report, which is updated periodically by the TRB Executive Committee, a series of challenging questions are posed to explore issues and opportunities that may arise 10 to 20 years into the future. These questions, 63 in all, have been organized into 12 topic areas and provide a way to frame future areas of research, policy analys...

TRB Special Report 329: Renewing the National Commitment to the Interstate Highway System: A Foundation for the Future explores pending and future federal investment and policy decisions concerning the federal Interstate Highway System. Congress asked the committee to make recommendations on the “features, standards, capacity needs, application of technologies, and intergovernmental roles to up...

TRB's Airport Cooperative Research Program (ACRP) latest Impacts on Practice explores the impact ACRP Synthesis 39 : Airport Wildlife Population Management has had on integrated wildlife management plans at airports. A wildlife biologist at Orlando International Airport utilized this report to develop a holistic approach to mitigating bird strikes with a specific species of heron that thrives i...

Transportation Research E-Circular 237: Innovations in Asphalt Mixture Design Procedures explores the fundamentals of asphalt mix design for improved durability and performance. Based off of presentations made at TRB's 95th Annual Meeting, the document examines presentations that cover ways to incorporate more binder into the mix with trials that modify the air void and void in mineral aggregat...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 890: Using Recycled Asphalt Shingles with Warm Mix Asphalt Technologies documents the development of a design and evaluation procedure that provides acceptable performance of asphalt mixtures incorporating warm mix asphalt (WMA) technologies and recycled asphalt shingles (RAS)—with and without recycled asphalt pave...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 257: A Mechanistic–Empirical Model for Top–Down Cracking of Asphalt Pavements Layers develops a calibrated mechanistic-empirical (ME) model for predicting the load-related top-down cracking in the asphalt layer of flexible pavements. Recent studies have determined that some load-related fatigue cracks in asphalt pavem...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 858: Quantifying the Effects of Preservation Treatments on Pavement Performance presents a proposed framework that uses performance measures to quantify the changes in pavement performance in terms of condition, service life, and life-cycle costs. Pavement preservation provides a means for maintaining and improving the ...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 878: Validation of the Louisiana Interlayer Shear Strength Test for Tack Coat evaluates and validates a test method to determine the interlayer shear strength of asphalt pavement layers. The report includes three appendices documenting the field project checklist, photos of existing pavement distress in two states, and ...

TRB's E-Circular 234: Relationships of Laboratory Mixture Aging to Asphalt Mixture Performance summarizes the results from TRB Session 462: Relationship of Laboratory Mix Aging to Asphalt Mixture Performance, which was held during the 2016 TRB Annual Meeting. This circular includes four papers on addressing laboratory mix aging and explore handling asphalt mixtures at a production facility, var...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 530: Construction and Rehabilitation of Concrete Pavements Under Traffic identifies practices from projects representing a wide range of conditions and techniques. The current state of the practice in constructing or rehabilitating concrete pavements under traffic relies primarily on a few high-profile and well-documented pro...

TRB’s Transportation Research Record: Journal of the Transportation Research Board has released 16 early access papers addressing pavements, including: Intelligent Compaction for Quality Control and Acceptance for Soil and Base Compaction through Statistical Analysis ( link ) Comparing Traffic Speed Deflectometer and Falling Weight Deflectometer Data ( link ) Time-Series Review of Highway Perfo...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 526: Inertial Profiler Certification for Evaluation of International Roughness Index determines the state of practice of certification of inertial profilers at the national and international levels. Inertial profilers are used to collect the repeatable and reproducible road profiles analyzed to calculate a smoothness or ride ...

TRB's National Cooperative Highway Research Program (NCHRP) has released a pre-publication, non-edited version of Research Report 876: Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. The report presents an approach for estimating the cost-effectiveness of including safety and operational improvements in a resurfacing, res...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 524: Aggregate Quality Requirements for Pavements Aggregate Quality Requirements for Pavements documents transportation agency requirements for the quality of aggregates for various pavement types. Constructing and maintaining pavements requires an abundant and dependable supply of quality aggregates. Aggregate comes from a w...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 877: Performance-Based Mix Design for Porous Friction Courses presents a proposed mix design method for porous asphalt friction course (PFCs). PFCs have been used in the United States for many years. Their open aggregate gradations and resultant high air void contents provide PFCs with the ability to quickly remove wate...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 515: Practices for Preventing Roadway Departures identifies and summarizes practices being used by state departments of transportation (DOTs) to prevent roadway departure crashes and to identify the data-driven advantages and disadvantages of these practices. More than half of all traffic fatalities result from roadway depart...

The National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) Final Report 193: DART Field Validation and Prototype Refinement documents a study to validate a field-ready prototype of the Duomorph Asphalt Rheology Tester (DART) as a low-cost and easy-to-use asphalt binder testing device. The DART system has the potential to provide a cost-effective ...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 516: Tack Coat Specifications, Materials, and Construction Practices provides state agencies across the United States with guidance as they reevaluate their tack coat specifications, the materials they use, and the practices by which the tack coats are placed. Pavement thickness design assumes that pavement works together as ...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 871: Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction presents a proposed standard method for long-term laboratory aging of asphalt mixtures for performance testing. The method is intended for consideration as a replacement for the method in AASHTO R 30, “Mixture Conditioning of Hot Mix Asphalt...

To keep pace with accelerating rate of research distribution, the Transportation Research Record: Journal of the Transportation Research Board is now publishing articles as soon as they are finalized. The latest papers to be published are as follows: Use of a Laser Diffractometer to Obtain the Particle Size Distribution of Fine-Grained Soils Interstate Speed Profiles Conditioning and Testing Pr...

The full edition of the July–August 2017  TR News  magazine is now available.  Moving research into practice is the theme of feature articles in this edition. Authors describe today’s successes, present a systematic approach that has proved effective at a state department of transportation, describe federal programs encouraging innovations at the state level, discuss initiatives ...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 863: Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete  presents procedures for determining material properties of cold-recycled asphalt mixtures for input to pavement structural design programs. Highway agencies are placing increasing emphasis on sustainability, recycling, a...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2632 consists of 15 papers that explore asphalt, including: Performance-Related Specifications for Asphalt Emulsions Used in Microsurfacing Treatments Chemical, Microstructural, and Rheological Characterizations of Binders to Evaluate Aging and Rejuvenation Statistical Analyses of Aggregate Mineral–Binder Ad...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2657 consists of 11 papers that explore geotechnical engineering, including: Long-Term Durability Studies on Chemically Treated Reclaimed Asphalt Pavement Material as a Base Layer for Pavements Effect of Microbial-Induced Calcite Precipitation on Surface Erosion and Scour of Granular Soils: Proof of Concept ...

The full edition of the May-June 2017 TR News is now available. This edition explores the role of transportation in economic development. Articles feature information about benefit-cost analysis, freight production models, transportation satellite accounts, and right sizing strategies. The TR News is TRB's bimonthly magazine featuring timely articles on innovative and state-of-the-art research ...

TRB's National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) has released Final Report 181: Development of Small Specimen Geometry for Asphalt Mixture Performance Testing. The use of small specimen geometries in Asphalt Mixture Performance Tester (AMPT) offer a means to measure as-built pavement layers. Small specimen geometries may improve the e...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2641 consists of 19 papers that explore pavements, including: Nondestructive In Situ Characterization of Elastic Moduli of Full-Depth Reclamation Base Mixtures Implementation of the Thin Bonded Concrete Overlay of Existing Asphalt Pavement Design Procedure in the AASHTOWare Pavement ME Design Software Evalua...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2630 consists of 18 papers that explore construction, including: Estimating Earthwork Volumes Through Use of Unmanned Aerial Systems Assessment of State Agencies’ Practices in Managing Geotechnical Risk in Design–Build Projects Roles and Responsibilities of Independent Cost Estimator in Construction Manager–...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2629 consists of 12 papers that explore concrete materials, including: Should Minimum Cementitious Contents for Concrete Be Specified? Effect of Specimen Size and Curing Condition on the Compressive Strength of Alkali-Activated Concrete Mitigation of Alkali–Silica Reaction by Hydrated Alumina Use of Fly Ash ...

TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2640 consists of 12 papers that explore pavements, including: Load Spectra–Incorporated Fatigue Cracking Model Implementation and Case Study Updates to Hourly Climate Data for Use in AASHTOWare Pavement Mechanistic–Empirical Design Autonomous Vehicles: Assessment of the Implications of Truck Positioning on F...