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
that have been released since June 2001 is available online. To search for older publications visit the
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 ...
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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...
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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...
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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...
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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...
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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...
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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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NCHRP Synthesis 576
October 11, 2021
The nature of the transportation project-level air quality arena is evolving, and there are potentially significant impacts to project schedules and budgets should air quality issues arise. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 576: Practices for Project-Level Analyses for Air Quality compiles and documents information regarding existing practices related to proje...
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NCHRP Synthesis 575
January 26, 2022
Roadway lighting is a widely recognized intervention for reducing nighttime crashes and isolated rural intersection lighting appears to be beneficial overall, but predicting the benefits likely at a specific location is very difficult. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 575: Lighting Practices for Isolated Rural Intersections is designed to help provide a found...
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NCHRP Synthesis 574
October 01, 2021
Agencies must consider many factors, such as work zone duration and weather conditions, in selecting appropriate pavement marking materials to effectively guide drivers through work zones. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 574: Temporary Pavement Markings Placement and Removal Practices in Work Zones addresses the need for more knowledge on which different typ...
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NCHRP Synthesis 573
September 10, 2021
State departments of transportation (DOTs) and other state and local agencies have implemented integrated flood warning and response systems to mitigate the effects of floods. These systems are critical for staging personnel, deciding when to close roads, inspecting bridges, tracking floods throughout the state, and planning recovery. The TRB National Cooperative Highway Research Program's NCHRP S...
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NCHRP Synthesis 572
August 19, 2021
Permitted movements of oversize and overweight (OS/OW) loads traditionally occur during the daytime on weekdays to allow for adequate staffing support and safety-focused practices. Due to increases in traffic congestion, safety concerns over fleet mixes, and other factors, many states began allowing or requesting those movements to occur during off-peak traffic hours, including nights and weekends...
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NCHRP Synthesis 571
February 11, 2022
Load ratings are used in part to allocate federal funding to agencies and to plan for repairing, replacing, and rehabilitating bridges. Therefore, load ratings can affect the movement of goods throughout a region and are vitally important to the continued safe and efficient operation of the highway system. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 571: Load Rating of ...
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NCHRP Synthesis 570
August 13, 2021
Although project closeout only entails a small portion of actual construction work, closing out highway construction projects for state departments of transportation (DOTs) is a complex and vital process that is a part of project delivery for highway construction projects. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 570: Practices for Closing Out Highway Projects from S...
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NCHRP Synthesis 569
August 25, 2021
Cold in-place recycling (CIR) is a process in which 3 to 4 inches of the existing asphalt pavement layers are pulverized, mixed with a recycling agent, and repaved in place. It provides agencies with cost-effective and environmentally friendly pavement maintenance and rehabilitation options for aged asphalt pavements. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 569: Pra...
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NCHRP Synthesis 568
July 09, 2021
Portland cement concrete (PCC) pavement joint sealing material technology has evolved in recent decades, and the effect of current joint sealant practice has not been well documented. Therefore, it is necessary to establish a standardized approach to joint sealant evaluation as well as to investigate the practice of joint sealant in PCC pavement design. The TRB National Cooperative Highway Researc...
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NCHRP Synthesis 567
July 30, 2021
Transportation Systems Management and Operations (TSMO) programs include elements of operations, planning, design, construction, maintenance, and safety. They are frequently complex and cross jurisdictional boundaries, involving traditional state departments of transportation (DOTs), local DOTs, and metropolitan planning organizations (MPOs), along with disruptive technology markets. The TRB Natio...
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NCHRP Synthesis 566
July 09, 2021
Bridge approach systems are used by state departments of transportation (DOTs) to form a smooth transition between the roadway and bridges. Adequate performance of bridge approaches is of extreme importance to transportation agencies as they affect both safety and the public perception of ride quality if the transition is not smooth. The TRB National Cooperative Highway Research Program's NCHRP Sy...
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NCHRP Synthesis 565
October 14, 2021
Pavement preservation is broadly acknowledged to provide network-wide benefits such as extending pavement life, enhancing system performance, reducing operation and maintenance costs, and improving safety. However, the performance of each pavement preservation project hinges on many factors. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 565: Maintenance and Surface Prepar...
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NCHRP Synthesis 564
May 06, 2021
State departments of transportation (DOTs) conduct planning and administer funding programs for the implementation of pedestrian and bicycle projects. The amount of federal funds available for these projects has grown steadily since 1992 under programs implemented as part of the Intermodal Surface Transportation Efficiency Act. The TRB National Cooperative Highway Research Program's NCHRP Synthesi...
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