National Cooperative Highway Research Program (NCHRP) Synthesis Reports

Syntheses report on the state of the practice based on literature reviews and surveys of recent activities in critical areas. Syntheses also inform airport managers about innovations being used by others to solve problems.
 
Below are the latest 20 NCHRP Synthesis Reports that have been produced by TRB.  A page highlighting NCHRP Reports that have been released since June 2001 is available online.  To search for older publications visit the TRB Online Bookstore or the TRB Publication Index.

Measuring Investments in Active Transportation When Accomplished as Part of Other Projects NCHRP Synthesis 596 September 09, 2022 There are few inventories of state investments in active transportation, at least partially because there is no federally mandated requirement to report on these investments. They are often accomplished as part of larger infrastructure projects, in order to realize the efficiencies inherent in making changes across modes on a network at the same time. The TRB National Cooperative Highway Research ...

Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements NCHRP Synthesis 595 September 09, 2022 Incompatibility between aggregate type and asphalt binder, presence of standing water or water under pressure in the pavement layers, and improper construction practices are some of the many factors that influence moisture susceptibility of flexible pavements. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 595: Practices for Assessing and Mitigating the Moisture Susceptibi...

Technological Capabilities of Departments of Transportation for Digital Project Management and Delivery NCHRP Synthesis 594 September 23, 2022 Technology solutions are in no short supply for state departments of transportation across the United States. With advancements in geospatial accuracy, cost reduction for technology components, and a need for effective staff utilization, a wealth of products and systems are becoming attractive options in the delivery of highway projects. The TRB National Cooperative Highway Research Program's NCHR...

3D Digital Models as Highway Construction Contract Documents NCHRP Synthesis 593 August 10, 2022 State departments of transportation (DOTs) have been investing in 3D modeling and sharing 3D digital models with contractors. Some DOTs have piloted the use of 3D digital models as contract documents, others continue to provide contractors with 3D digital models for information purposes, and some have not begun using 3D digital models in construction. The TRB National Cooperative Highway Research ...

Practices for Balancing Safety Investments in a Comprehensive Safety Program NCHRP Synthesis 592 July 22, 2022 The Highway Safety Improvement Program (HSIP) is a core federal-aid highway program with the purpose of achieving significant reductions in fatalities and serious injuries on all public roads. Although there are federal requirements that guide state HSIP efforts, there are several variations in how state departments of transportation (DOTs) identify, prioritize, and evaluate HSIP projects. The TRB...

Use of Safety Management Systems in Managing Highway Maintenance Worker Safety NCHRP Synthesis 591 July 29, 2022 Safety and health programs are vital to the success of state departments of transportation (DOTs). While the safety of all DOT employees is paramount, maintenance and other field workers are exposed to unique hazards that demand a higher level of management than traditional office-based positions. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 591: Use of Safety Management...

Agency Use of Quality Control Plans for Administering Quality Assurance Specifications NCHRP Synthesis 590 July 22, 2022 For years, state departments of transportation (DOTs) were solely responsible for quality control (QC) and performed testing and inspection to verify construction quality. However, since the 1970s, many state DOTs have transferred the responsibility for QC processes of their highway-construction projects to contractors. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 590: A...

Automated Data Collection and Quality Management for Pavement Condition Reporting NCHRP Synthesis 589 September 01, 2022 Automated collection of pavement data allows agencies to collect data on pavement health, including cracking, rutting, faulting, and roughness, at highway speeds. This provides important information for better pavement decision-making. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 589: Automated Data Collection and Quality Management for Pavement Condition Reporting docum...

Design Practices for Rock Slopes and Rockfall Management NCHRP Synthesis 588 June 29, 2022 While there are no national standards for rock slope design and rockfall management, many state departments of transportation (DOTs) have developed their own design goals and objectives. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 588: Design Practices for Rock Slopes and Rockfall Management documents DOT practices for the design of rock slopes and rockfall mitigation s...

Use of Smart Work Zone Technologies for Improving Work Zone Safety NCHRP Synthesis 587 June 30, 2022 To make work zones safer, state departments of transportation (DOTs) use smart technologies with specialized components, such as sensors, communications, software, and electronic equipment, to manage traffic and operations and disseminate traveler information. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 587: Use of Smart Work Zone Technologies for Improving Work Zone Sa...

Use of Recycling Agents in Asphalt Concrete Mixtures NCHRP Synthesis 586 June 01, 2022 Although the use of recycled asphalt materials (RAM) in new asphalt mixtures can reduce the amount of virgin and nonrenewable materials required and increase the rutting resistance of pavements, it may also compromise cracking resistance. To mitigate this issue, asphalt mixtures containing RAM may require the use of a softer binder or recycling agent (RA). The TRB National Cooperative Highway Rese...

Bridge Element Data Collection and Use NCHRP Synthesis 585 September 09, 2022 Initial efforts to define and collect bridge element data in the United States started in the late 1990s with the development and implementation of bridge management systems (BMSs). Over the years, the bridge management community provided feedback and made suggestions to improve the bridge element inspection methodology. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 585: ...

Visualization of Highway Performance Measures NCHRP Synthesis 584 July 13, 2022 Visualizations are tools for analyzing, reporting, and communicating the complexities of a transportation system and for synthesizing these intricacies into presentations that can be easily understood. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 584: Visualization of Highway Performance Measures documents current practices and methods used by state departments of transp...

Implementation of Subsurface Utility Engineering for Highway Design and Construction NCHRP Synthesis 583 May 18, 2022 While it is recognized to be in the public interest to permit the installation of utility infrastructure in roadway rights-of-way, the practice has contributed to utility-related issues being one of the leading causes of delays for transportation projects. Subsurface utility engineering (SUE) is an approach state departments of transportation (DOTs) have implemented to locate utilities and assist ...

Highway Infrastructure Inspection Practices for the Digital Age NCHRP Synthesis 582 May 20, 2022 Historically, state departments of transportation (DOTs) have employed on-site workforces to execute infrastructure inspection using traditional inspection methods. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 582: Highway Infrastructure Inspection Practices for the Digital Age documents the various technologies - such as unmanned aircraft systems (UASs), embedded and re...

Rehabilitation of Culverts and Buried Storm Drain Pipes NCHRP Synthesis 581 May 16, 2022 Departments of transportation (DOTs) are increasing employment of asset management strategies in response to federal and state initiatives. Low-cost and effective treatments applied throughout the life of the asset can be employed prior to significant asset degradation, which otherwise would likely require a high-cost reactionary treatment. The TRB National Cooperative Highway Research Program's N...

Practices for Ensuring the Smoothness of Concrete Bridge Decks NCHRP Synthesis 580 April 14, 2022 Rough bridge surfaces can increase user costs by accumulative wear and tear on vehicles, increase freight costs resulting from damage to goods or packaging, add to potential safety concerns with nonuniform tire loads, decrease the life of a structure by increasing dynamic loads, and reduce user satisfaction. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 580: Practices for...

Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance NCHRP Synthesis 579 April 22, 2022 Subsurface drainage is known to pavement professionals to be an important factor affecting pavement performance and preservation of public investment, and numerous studies have emphasized its importance. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 579: Subsurface Drainage Practices in Pavement Design, Construction, and Maintenance documents the current state of practice...

Use of Unmanned Aerial Systems for Highway Construction NCHRP Synthesis 578 March 24, 2022 In the last decade, new technologies have transformed all stages of highway construction as more industry stakeholders have begun incorporating new technologies into their daily construction activities. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 578: Use of Unmanned Aerial Systems for Highway Construction documents the use of Unmanned Aircraft Systems (UAS) by state de...

Collaborative Practices for Performance-Based Asset Management Between State DOTs and MPOs NCHRP Synthesis 577 September 17, 2021 The degree of collaboration between state departments of transportation (DOTs) and metropolitan planning organzations (MPOs) on goals and performance targets for management of transportation assets varies. Collaboration may also involve investment decisions. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 577: Collaborative Practices for Performance-Based Asset Management B...

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