Full-depth reclamation (FDR) is a method to recycle in-place asphalt material for reconstruction and rehabilitation of flexible pavements.
NCHRP Synthesis 657: Full-Depth Reclamation: Current Practices, from TRB's National Cooperative Highway Research Program, documents practices used by state departments of transportation, including classification of FDR types, site selection, specifications and guidelines for FDR mix design, and test methods to evaluate FDR quality.
146 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99545-0
ISBN Ebook: 0-309-99546-9
DOI:
https://doi.org/10.17226/29222
National Academies of Sciences, Engineering, and Medicine. 2025. Full-Depth Reclamation: Current Practices. Washington, DC: The National Academies Press.
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Automatic vehicle monitoring (AVM) and vehicle health monitoring (VHM) are becoming more widely utilized by transit agencies across the United States. These agencies are increasingly interested in using predictive maintenance technology (PMT), artificial intelligence (AI), and other technologies, but the overall capabilities and benefits of these technologies are still emerging.
TCRP Synthesis 185: Use of Automatic Vehicle Monitoring, Vehicle Health Monitoring, and Diagnostic Systems by Transit Agencies, from TRB's Transit Cooperative Research Program, explores how AVM, VHM, and other technologies are utilized to monitor an array of onboard vehicle components in order to assist in the early identification of potential mechanical issues, thus supporting effective maintenance practices.
90 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99599-X
ISBN Ebook: 0-309-99600-7
DOI:
https://doi.org/10.17226/29236
National Academies of Sciences, Engineering, and Medicine. 2025. Use of Automatic Vehicle Monitoring, Vehicle Health Monitoring, and Diagnostic Systems by Transit Agencies. Washington, DC: The National Academies Press.
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Emerging ground access technologies, such as autonomous, automated, connected, and electric vehicles, will affect airport landside operations. Curbside traffic will change, becoming more complex as automotive technologies become more innovative. Other mass and personal transportation modes that leverage both legacy and new technologies will also provide mobility to and from the airport. Airport operators will need to understand the impacts to landside operations to effectively plan for passenger terminal facilities. They will also have to consider accessibility, costs, legal and regulatory implications, sustainability, and resilience.
ACRP Research Report 269: Enhancing Airport Access with Emerging Mobility, from TRB's Airport Cooperative Research Program, provides strategies for addressing current and future transportation and ground access technologies and for planning landside facilities that incorporate these emerging technologies.
328 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-73198-4
ISBN Ebook: 0-309-73199-2
DOI:
https://doi.org/10.17226/28600
National Academies of Sciences, Engineering, and Medicine. 2025. Enhancing Airport Access with Emerging Mobility. Washington, DC: The National Academies Press.
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Letter
TRB's Research and Technology Coordinating Committee provides strategic advice to the Federal Highway Administration (FHWA) on its research, development and technology (RD&T) program. The committee's letter report to FHWA describes how the agency's RD&T program functions as a key element in the nation's highway RD&T enterprise. After examining the goals, capabilities, and constraints of the FHWA RD&T program, the committee recommends steps the agency can take to further strengthen its crucial role in accelerating innovation in the highway field.
14 pages
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ISBN Ebook: 0-309-60003-0
DOI:
https://doi.org/10.17226/29262
National Academies of Sciences, Engineering, and Medicine. 2025. Research and Technology Coordinating Committee Letter Report: September 2025. Washington, DC: The National Academies Press.
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The COVID-19 pandemic-induced shift toward remote and hybrid work arrangements significantly impacted peak hour transit ridership across the United States; however, offpeak ridership exhibited greater resilience. As a result, many transit agencies began reevaluating their service strategies, placing greater emphasis on nighttime service enhancements to better serve emerging travel patterns and support those who rely on transit outside conventional work hours.
TCRP Synthesis 181: Planning and Operations Initiatives to Support Nighttime Transit Ridership, from TRB's Transit Cooperative Research Program, documents current practices undertaken by transit agencies to support nighttime transit ridership and focuses on how transit agencies prioritize service improvements to support nighttime transit demand and address the needs of essential workers. It includes a survey of 25 transit agencies plus five case examples that examine strategies related to safety, operations, resource allocation, ridership trends, and partnerships.
82 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99541-8
ISBN Ebook: 0-309-99542-6
DOI:
https://doi.org/10.17226/29221
National Academies of Sciences, Engineering, and Medicine. 2025. Planning and Operations Initiatives to Support Nighttime Transit Ridership. Washington, DC: The National Academies Press.
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Young drivers with neurodevelopmental disabilities may be at more risk for motor vehicle crashes due to behavior characteristics commonly associated with these conditions. In recent years, a growing body of research has examined driving risks for teens with autism and those with attention-deficit/hyperactivity disorder (ADHD).
BTSCRP Research Report 15: Teen Driving Performance Associated with Distraction, ADHD, and Other Risk Factors, from TRB's Behavioral Traffic Safety Cooperative Research Program, provides further insights into traffic safety risks for teen drivers with different levels of ADHD. The report concludes that teen drivers with ADHD tend to look away from the road more frequently and may be at an elevated risk for missed hazards.
40 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99489-6
ISBN Ebook: 0-309-99490-X
DOI:
https://doi.org/10.17226/29209
National Academies of Sciences, Engineering, and Medicine. 2025. Teen Driving Performance Associated with Distraction, ADHD, and Other Risk Factors. Washington, DC: The National Academies Press.
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Over the past decade, public transit agencies across the United States and Canada have increasingly adopted low-income fare discount programs to improve transit affordability and accessibility. The COVID-19 pandemic accelerated this trend, prompting agencies to reevaluate services and expand affordable transit choices. These programs offer various benefits such as fare discounts, free rides, or discounted passes.
TCRP Synthesis 182: Providing Low-Income Fare Discounts at Public Transit Agencies, from TRB's Transit Cooperative Research Program, documents the current state of the practice of low-income fare discount programs offered by North American transit agencies.
126 pages
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paperback
ISBN Paperback: 0-309-99495-0
ISBN Ebook: 0-309-99496-9
DOI:
https://doi.org/10.17226/29210
National Academies of Sciences, Engineering, and Medicine. 2025. Providing Low-Income Fare Discounts at Public Transit Agencies. Washington, DC: The National Academies Press.
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Transportation leaders encounter multiple situations daily that require decisions to be made. These decisions can have impacts on billions of dollars or an entire state of travelers, and they often need to be made quickly and without all the information available.
NCHRP Research Report 1162: Advancing the Art and Science of Decision-Making: A Guide, from TRB’s National Cooperative Highway Research Program, combines practical advice and experiences from transportation agency executives with the latest findings from cognitive science research to supplement leaders’ toolboxes for good decision-making.
87 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-60018-9
ISBN Ebook: 0-309-60016-2
DOI:
https://doi.org/10.17226/29265
National Academies of Sciences, Engineering, and Medicine. 2025. Advancing the Art and Science of Decision-Making: A Guide. Washington, DC: The National Academies Press.
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The transportation industry continues to face a range of unforeseen and evolving challenges to transportation assets and operations that affect the performance and resilience of transportation systems and networks. For example, significant disruptions to supply chains and traffic patterns were outcomes of the unanticipated collapse of the Key Bridge in Baltimore, Maryland.
NCHRP Research Report 1146: Risk Management at State DOTs: Building Momentum and Sustaining the Practice, from TRB's National Cooperative Highway Research Program, provides guidelines for state departments of transportation and other agencies to establish and maintain a risk management culture and practice.
104 pages
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paperback
ISBN Paperback: 0-309-99340-7
ISBN Ebook: 0-309-99341-5
DOI:
https://doi.org/10.17226/29144
National Academies of Sciences, Engineering, and Medicine. 2025. Risk Management at State DOTs: Building Momentum and Sustaining the Practice. Washington, DC: The National Academies Press.
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The availability of large-scale, high-resolution, and consistently collected road data will improve the safety of all road users. The use of artificial intelligence (AI), machine learning (ML), and big data is key in providing the information needed to power data-driven, public, and proprietary safety analysis tools, as well as predictive and other systemic safety tools.
NCHRP Research Report 1152: Leveraging Artificial Intelligence and Big Data to Enhance Safety Analysis: A Guide, a publication from TRB's National Cooperative Highway Research Program, outlines the limitations of traditional safety evaluations and demonstrates how new data sources— like connected vehicles, LiDAR, video analytics, and edge devices—can enhance safety insights and predictive capabilities. Case studies include successful pilots with the Oregon Department of Transportation, showcasing ML models for inventorying streetlight luminaires to inform crash risk analysis, and the City of Bellevue, WA, analyzing vehicle turning behavior to improve safety at signalized intersections.
110 pages
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paperback
ISBN Paperback: 0-309-59960-1
ISBN Ebook: 0-309-59961-X
DOI:
https://doi.org/10.17226/29098
National Academies of Sciences, Engineering, and Medicine. 2025. Leveraging Artificial Intelligence and Big Data to Enhance Safety Analysis: A Guide. Washington, DC: The National Academies Press.
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Demand response transportation (DRT) providers have consistently looked for operational designs and mechanisms to improve service efficiencies and lower operational costs. DRT services, which include ADA (Americans with Disabilities Act) complementary paratransit and general public DRT services, such as advance reservation dial-a-ride services and ondemand microtransit services, are inherently less efficient to operate due to circumstances of geography, population locations, program rules, and “points of interest” (relevant transit locations and destinations) for travel.
TCRP Synthesis 183: Operational and Service Factors When Integrating or Consolidating ADA Paratransit and On-Demand Services, from TRB's Transit Cooperative Research Program, provides information, analysis, and examples of the current state of the practice in integrating or consolidating ADA paratransit and other types of paratransit service with on-demand microtransit for the general public, including documented findings and results from the agencies, municipalities, and other local government entities providing these commingled trips.
166 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99475-6
ISBN Ebook: 0-309-99476-4
DOI:
https://doi.org/10.17226/29206
National Academies of Sciences, Engineering, and Medicine. 2025. Operational and Service Factors When Integrating or Consolidating ADA Paratransit and On-Demand Services. Washington, DC: The National Academies Press.
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For transit operators with zero-emission transit buses (ZEB) in their fleets, the primary concern is whether the vehicles can meet the agency’s service requirements for both regularly scheduled service and for unscheduled service to address local or regional events and emergencies. This concern applies both at the individual route and fleet levels.
TCRP Research Report 256: Resilient Zero-Emission Transit Bus Fleets: A Guide, from TRB's Transit Cooperative Research Program, provides a framework for transit agencies to update their resilience plans to operate ZEB fleets. It also offers a roadmap for transit agencies to integrate their existing zero-emission vehicle (ZEV) transition strategies into broader resilience planning efforts.
106 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99471-3
ISBN Ebook: 0-309-99472-1
DOI:
https://doi.org/10.17226/29205
National Academies of Sciences, Engineering, and Medicine. 2025. Resilient Zero-Emission Transit Bus Fleets: A Guide. Washington, DC: The National Academies Press.
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Recent years have seen an increased focus on the performance of roadside hardware. As the use of high-tension cable barrier (HTCB) systems increased across the United States, the transportation industry determined that there was a research need to summarize the state of practice for HTCB systems.
NCHRP Research Report 1156: Material Requirements for High-Tension Cable Barriers: A Guide, from TRB's National Cooperative Highway Research Program, presents a guide on material requirements for highway guardrail systems and their components to provide consistency with current roadside safety hardware requirements.
The report follows up on NCHRP Research Report 1020: Investigation of Material Requirements for Highway Guardrail Systems.
150 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99428-4
ISBN Ebook: 0-309-99429-2
DOI:
https://doi.org/10.17226/29173
National Academies of Sciences, Engineering, and Medicine. 2025. Material Requirements for High-Tension Cable Barriers: A Guide. Washington, DC: The National Academies Press.
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The Federal Communications Commission’s current licensing freeze, while it considers new rules for the 4.9 GHz spectrum band, leaves a limited number of options for new use of the band. While it is not presently known when the freeze will be lifted, and if any new rules will be put into effect, there are nevertheless currently several potential opportunities for state department of transportation operations in the band.
NCHRP Web-Only Document 422: Planning for 4.9 GHz Spectrum Changes, from TRB's National Cooperative Highway Research Program, provides background and guidance for transportation agencies that wish to implement systems in the band.
16 pages
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ISBN Ebook: 0-309-59969-5
DOI:
https://doi.org/10.17226/29256
National Academies of Sciences, Engineering, and Medicine. 2025. Planning for 4.9 GHz Spectrum Changes. Washington, DC: The National Academies Press.
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State departments of transportation (DOTs) have begun changing the medium of construction contract documents from paper or 2D plans to 3D models that are contractually binding. The driver of this major change is the ability for contractors and inspectors to use 3D models directly to support project activities and communicate the design intent. However, changing the medium of construction contract documents has created challenges for state DOTs, including a need for robust review and documentation procedures as well as a lack of automated quality control and quality assurance management processes for 3D models.
NCHRP Research Report 1153: Digital Model–Based Project Development and Delivery: A Guide for Quality Management, from TRB’s National Cooperative Highway Research Program, presents state-of-the-art information to assist state DOTs in their review of 3D models that are contractually binding and to advance the use of digital project development and delivery.
Supplemental to the report are NCHRP Web-Only Document 428: Quality Management for Digital Model–Based Project Development and Delivery, Appendix F Addendum: Review Checklist Spreadsheet, an implementation plan, and a webinar presentation.
106 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99422-5
ISBN Ebook: 0-309-99423-3
DOI:
https://doi.org/10.17226/29171
National Academies of Sciences, Engineering, and Medicine. 2025. Digital Model–Based Project Development and Delivery: A Guide for Quality Management. Washington, DC: The National Academies Press.
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NCHRP Web-Only Document 428: Quality Management for Digital Model–Based Project Development and Delivery, from TRB’s National Cooperative Highway Research Program, addresses two key challenges for state departments of transportation and other highway agencies: the use of 3D models as a new way to review construction designs and the review of the 3D models themselves.
The document is supplemental to NCHRP Research Report 1153: Digital Model–Based Project Development and Delivery: A Guide for Quality Management.
150 pages
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8.5 x 11
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ISBN Ebook: 0-309-99426-8
DOI:
https://doi.org/10.17226/29172
National Academies of Sciences, Engineering, and Medicine. 2025. Quality Management for Digital Model–Based Project Development and Delivery. Washington, DC: The National Academies Press.
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Airports, while physically located within individual states, operate as instruments of commerce subject to federal jurisdiction as part of the national transportation system. This duality, requiring airports to navigate multiple layers of laws and regulations, is particularly significant in the context of cannabis, where some states have legalized the substance for certain uses while federal law continues to prohibit it.
ACRP Legal Research Digest 49: Legal Impacts to Airports from State Legalization of Cannabis, from TRB's Airport Cooperative Research Program, provides insight into the legal impacts to airports from these and ongoing efforts by certain states to legalize cannabis by identifying key issues and corresponding legal guidance, where available.
44 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99298-2
ISBN Ebook: 0-309-99299-0
DOI:
https://doi.org/10.17226/29135
National Academies of Sciences, Engineering, and Medicine. 2025. Legal Impacts to Airports from State Legalization of Cannabis. Washington, DC: The National Academies Press.
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Commuter rail services operate in more than 20 North American regions, connecting communities to urban downtowns. These services enjoyed decades of growth, with ridership increasing by 50 percent between 1990 and 2019. However, travel demand shifts brought on by the COVID-19 pandemic and continued work-from-home patterns caused ridership to collapse and only partially recover. This sudden change also upended the traditional financial model, in which fare revenues covered more than half of operating costs. While commuter rail providers vary in size and structure, they all share an uncertain future in solidifying a long-term and financially sustainable role in serving regional transportation demands.
TCRP Research Report 254: The Future of Commuter Rail in North America, from TRB's Transit Cooperative Research Program, examines the history of commuter rail in North America, evaluates current trends, presents constraints, reviews case studies, and explores strategies— including alternative approaches to service schedules, simplified fare structures, and infrastructure options—to address changing goals and circumstances at the agency, regional, and national levels in the United States and Canada.
82 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99266-4
ISBN Ebook: 0-309-99267-2
DOI:
https://doi.org/10.17226/29128
National Academies of Sciences, Engineering, and Medicine. 2025. The Future of Commuter Rail in North America. Washington, DC: The National Academies Press.
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