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) has released a pre-publication, non-edited version of Research Report 894: Evaluating the Performance of Longitudinal Barriers on Curved, Superelevated Roadway Sections. Curved, high-speed roadways are usually superelevated to make the curved roadway easier for vehicles to navigate. However, the angle of these roadways can cause an inc...

TRB's National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) Final Report 186: Development of an Electrical Probe for Rapid Assessment of Ground Improvement explores new technologies that can be used in soil improvement. Soil improvement has numerous applications in transportation construction, including embankment stabilization, underpinning bri...

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 National Cooperative Highway Research Program (NCHRP) Research Report 884: Guidelines for Managing Geotechnical Risks in Design–Build Projects provides guidelines for the implementation of geotechnical risk management measures for design –build project delivery . The guidelines provide five strategies for aligning a transportation agency and its design–builder’s perception of geotechnical...

TRB's National Cooperative Highway Research Program (NCHRP)  Web-Only Document 247: Managing Geotechnical Risks in Design–Build Projects documents the research effort to produce NCHRP Research Report 884 : Guidelines for Managing Geotechnical Risks in Design–Build Projects. NCHRP Research Report 884 provides guidelines for the implementation of geotechnical risk management measures for des...

TRB's E-Circular 235: Glossary of Transportation Construction Quality Assurance Terms: Seventh Edition contains common terms and accepted practice in transportation construction quality assurance terminology. Transportation construction quality assurance (QA), like many other specialized subject areas, has its own unique language containing numerous technical terms or expressions having very sp...

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...

The latest edition of Research Pays Off explores the Georgia Department of Transportation (DOT)'s use of alternative delivery methods to compress and accelerate the delivery of projects from engineering through construction through public–private partnerships (PPPs) and design–build (DB) methods.This article discusses the legislation that allowed Georgia DOT to build partnerships with private f...

A featured article in the July-August 2018 issue of the TR News investigates how risk is addressed in both the traditional project delivery method and in alternative project delivery methods used by departments of transportation across the country.  The TR News is TRB's bimonthly magazine featuring timely articles on innovative and state-of-the-art research and practice in all modes of tra...

A featured article in the July-August 2018 issue of the TR News examines the latest application and implementation of alternative contracting methods for faster project delivery of transportation infrastructure. The TR News is TRB's bimonthly magazine featuring timely articles on innovative and state-of-the-art research and practice in all modes of transportation. It also includes brief news it...

The July–August issue of TR News examines 20 years of research and TRB activities on alternative contracting methods (ACM) and success stories from implementing research innovations. Explored are pioneering tools and contracting techniques used by state departments of transportation such as Georgia and Colorado, along with tested project delivery methods, selection tools for transit, internatio...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 518: Staffing for Alternative Contracting Methods documents current practices in state departments of transportation (DOTs) staffing and organizational structure for alternative contracting methods (ACMs). ACMs include design–build, construction manager/general contractor, public–private partnerships, and other innovative con...

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 Transportation Research Record: Journal of the Transportation Research Board has released 12 early access papers addressing construction, including: Leveraging Intelligent Compaction and Thermal Profiling Technologies to Improve Asphalt Pavement Construction Quality: A Case Study ( link ) Managing Public Communication Strategies in Accelerated Highway Construction Projects ( link ) Traffi...

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 519: The Renewal of Stormwater Systems Using Trenchless Technologies summarizes technologies used for the renewal of stormwater systems, including new, emerging, and underutilized trenchless methods, and identifies future research needs. Both trenchless replacement and trenchless renewal methods can reduce negative impacts as...

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...

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) Web-Only Document 250: Use of Automated Machine Guidance within the Transportation Industry studies automated machine guidance (AMG) implementation barriers and develop strategies for effective implementation of AMG technology in construction operations. AMG links design software with construction equipment to direct the operations of ...

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...

TRB's E-Circular 230: Culverts and Soil–Structure Interaction: Fifty Years of Change and a Twenty-Year Projection summarizes the presentations from the TRB 93rd Annual Meeting on January 14, 2014 in Washington, D.C. In the past 40 to 50 years have seen significant changes in the pipe industry in terms of materials used, structure sizes, shapes, and joint capabilities. Design methodologies ...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 242: Recommended AASHTO Guide Specifications for ABC Design and Construction documents the results of a synthesis of past research regarding Accelerated Bridge Construction (ABC), leading to the development of Guide Specifications for Accelerated Bridge Construction. Part 1 of the report includes Design Specifications...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 870: Field Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content explores the use of corrugated high density polyethylene (HDPE) pipe manufactured with recycled content and proposes guidelines for manufacturing these pipes to ensure they meet the service life requirements for the given appl...

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...

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...