The number of incidents involving disruptive, threatening, or violent behavior in commercial airports has increased in recent years. However, much of the response to these incidents has been focused on addressing behavior in flight, leaving airport operators with limited guidelines tailored to the airport environment.
ACRP Research Report 280: Reducing and Managing Disruptive and Unruly Behavior in Airports: A Guide, from TRB's Airport Cooperative Research Program, presents a practical guide for reducing and responding to incidents of disruptive, threatening, or violent behavior in an airport setting. The guide examines the topic holistically and offers a structured approach to understanding root causes, prevention and mitigation strategies, coordinated response, and postincident analysis.
100 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99376-8
ISBN Ebook: 0-309-99377-6
DOI:
https://doi.org/10.17226/29156
National Academies of Sciences, Engineering, and Medicine. 2025. Reducing and Managing Disruptive and Unruly Behavior in Airports: A Guide. Washington, DC: The National Academies Press.
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The level of service (LOS) concept has been used for over 50 years by state departments of transportation (DOTs) in the U.S. for policy setting, planning, analysis, and communication efforts. Adoption of the LOS framework by individual state DOTs has generally been consistent with the Highway Capacity Manual, although usage and application may vary across different state DOTs.
NCHRP Synthesis 652: Traffic Capacity Level of Service: Adaptations and Usage, from TRB's National Cooperative Highway Research Program, includes findings that may assist state DOTs in improving their LOS practices and policies.
104 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99336-9
ISBN Ebook: 0-309-99337-7
DOI:
https://doi.org/10.17226/29143
National Academies of Sciences, Engineering, and Medicine. 2025. Traffic Capacity Level of Service: Adaptations and Usage. Washington, DC: The National Academies Press.
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The Safe System approach is a holistic approach that provides a framework for making the U.S. national transportation system safer. It is based on building and reinforcing multiple layers of protection to prevent crashes from happening and minimize the harm caused when crashes occur. This safety approach differs from conventional ones because it focuses on human vulnerability and creates a system with many redundancies to protect all transportation users.
NCHRP Research Report 1135: A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations, from TRB's National Cooperative Highway Research Program, presents information for applying the Safe System approach among state departments of transportation and other transportation agencies.
Supplemental to the report is NCHRP Web-Only Document 413: Applying the Safe System Approach to Transportation Planning, Design, and Operations.
102 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99350-4
ISBN Ebook: 0-309-99352-0
DOI:
https://doi.org/10.17226/29147
National Academies of Sciences, Engineering, and Medicine. 2025. A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
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The Safe System paradigm represents a pivot away from the “Responsibility” paradigm, which emerged in the 1980s in the United States. Whereas until recently, speed was considered safe—assuming drivers were responsible—and other road users were generally thought to be responsible for their own safety and the safety of others, the Safe System paradigm recognizes the fallibility of humans and places greater responsibility on system operators for keeping road users safe and protected.
NCHRP Web-Only Document 413: Applying the Safe System Approach to Transportation Planning, Design, and Operations, from TRB's National Cooperative Highway Research Program, is supplemental to NCHRP Research Report 1135: A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations.
53 pages
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8.5 x 11
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ISBN Ebook: 0-309-99355-5
DOI:
https://doi.org/10.17226/29148
National Academies of Sciences, Engineering, and Medicine. 2025. Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
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Transportation planning agencies and officials face a rapidly evolving technical, policy, legislative, and procedural environment. Agency professionals often seek the guidance of peers and experts to help them effectively address these challenges. Challenges include managing the demand for new transportation technologies and services within the confinements of existing streets, navigating the effects of growing e-commerce on travel patterns, managing resilience and risks, and implementing transportation planning in compliance with federal and state laws and regulations.
NCHRP Research Report 1158: Developing Snapshots for Transportation Planning, from TRB's National Cooperative Highway Research Program, documents the process of developing four Snapshots of Planning Practices, concise and visually appealing documents that report on current planning practices in use by transportation agencies in four practice areas: Complete Streets, Data Sharing for Performance Management, Collaboration on Local Freight Delivery, and Economic Analysis to Support Decision-Making.
Supplemental to the report is NCHRP Web-Only Document 431: Snapshots of Planning Practices.
52 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99418-7
ISBN Ebook: 0-309-99419-5
DOI:
https://doi.org/10.17226/29170
National Academies of Sciences, Engineering, and Medicine. 2025. Developing Snapshots for Transportation Planning. Washington, DC: The National Academies Press.
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NCHRP Web-Only Document 431: Snapshots of Planning Practices, from TRB's National Cooperative Highway Research Program, presents a series of illustrated "snapshots" that serve as a resource for transportation-planning practice development and provide information for realistic practice implementation and program advancement.
The document is supplemental to NCHRP Research Report 1158: Developing Snapshots for Transportation Planning.
22 pages
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8.5 x 11
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ISBN Ebook: 0-309-99436-5
DOI:
https://doi.org/10.17226/29175
National Academies of Sciences, Engineering, and Medicine. 2025. Snapshots of Planning Practices. Washington, DC: The National Academies Press.
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On transit systems across the United States, rising rates of drug use along with deteriorating safety conditions for customers and staff have become increasingly pressing and complex issues for transit agencies to solve. Many challenges surround agencies’ responses to drug use on transit, such as inconsistent data collection and the low uptake of support services.
TCRP Synthesis 179: The Impacts of and Response to Drug Use on Transit, from TRB's Transit Cooperative Research Program, documents and synthesizes the current practices of transit agencies in addressing the consumption and distribution of illegal drugs on their systems, as well as the resulting effects on customer and staff safety and security.
90 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99396-2
ISBN Ebook: 0-309-99397-0
DOI:
https://doi.org/10.17226/29161
National Academies of Sciences, Engineering, and Medicine. 2025. The Impacts of and Response to Drug Use on Transit. Washington, DC: The National Academies Press.
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In recent years, Lidar technology has improved. Additionally, the experiences of state departments of transportation (DOTs) with Lidar have grown, and documentation of existing practices, business uses, and needs would now benefit state DOTs’ efforts.
NCHRP Synthesis 642: Practices for Collecting, Managing, and Using Light Detection and Ranging Data, from TRB’s National Cooperative Highway Research Program, documents state DOTs’ practices related to technical, administrative, policy, and other aspects of collecting, managing, and using Lidar data to support current and future practices.
210 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-71799-X
ISBN Ebook: 0-309-71800-7
DOI:
https://doi.org/10.17226/29042
National Academies of Sciences, Engineering, and Medicine. 2025. Practices for Collecting, Managing, and Using Light Detection and Ranging Data. Washington, DC: The National Academies Press.
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In the face of growing uncertainties, supply chain resilience is coming to be seen as increasingly important. Vulnerabilities revealed during the COVID-19 pandemic have highlighted the fragility of the global supply chain but have also spurred research and uncovered effective practices and strategies to mitigate and manage supply chain disruptions.
NCHRP Research Report 1154: Supply Chain Challenges and Solutions amid COVID-19, from TRB's National Cooperative Highway Research Program, provides an overview for understanding the elements of supply chains, describing the suppliers, manufacturers, distributors, retailers, and end users, as well as the supporting infrastructure. The supply chain challenges identified in this report are organized into eight categories: physical congestion and capacity, information and data, security, equipment, workforce, regulatory, and supplier source.
76 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99366-0
ISBN Ebook: 0-309-99367-9
DOI:
https://doi.org/10.17226/29153
National Academies of Sciences, Engineering, and Medicine. 2025. Supply Chain Challenges and Solutions amid COVID-19. Washington, DC: The National Academies Press.
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Consensus
Air traffic controller staffing is essential for aviation safety in the United States. Therefore, the Federal Aviation Administration (FAA) should continue to increase air traffic controller hiring, improve training success rates, incentivize transfers from overstaffed to understaffed airports, and implement robust fatigue management systems and efficient shift-scheduling tools. FAA should also rebuild its controller staffing based on its traditional modeling approach—as refined by needed updates and with local input—rather than adopting newer facility staffing models the agency developed collaboratively with members of the National Air Traffic Controllers Association. FAA should also conduct recommended research to improve understanding about the relationship between facility staffing levels and safety and validate its facility models using risk indicators, some of which are confidential and therefore not available to the committee that prepared the report.
These are among the recommendations in TRB Special Report 357: The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations, from the Transportation Research Board of the National Academies of Sciences, Engineering, and Medicine. The report, called for by Congress, notes that about 30 percent of the FAA facilities are staffed at more than 10 percent below their staffing targets and about 30 percent of facilities are staffed at 10 percent or more above their staffing targets. FAA experienced a series of externally imposed constraints on hiring since 2013, including two government shutdowns over budget and fiscal policy and the COVID-19 pandemic, that have notably affected several of the largest facilities that serve many of the country’s largest airports and have had an outsized effect on passenger delays.
284 pages
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6 x 9
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paperback
ISBN Paperback: 0-309-99224-9
ISBN Ebook: 0-309-99225-7
DOI:
https://doi.org/10.17226/29112
National Academies of Sciences, Engineering, and Medicine. 2025. The Air Traffic Controller Workforce Imperative: Staffing Models and Their Implementation to Ensure Safe and Efficient Airspace Operations. Washington, DC: The National Academies Press.
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Mechanically stabilized earth (MSE) walls are widely used in transportation projects due to their cost-saving, time-efficient, and resilient nature. However, most of the walls constructed so far have been built too recently to allow assessment of whether or not they would meet the desired design life. Additionally, design guidelines, construction materials, and protocols have evolved greatly since the technology was first adopted.
NCHRP Synthesis 644: Asset Management Practices for Mechanically Stabilized Earth Walls, from TRB's National Cooperative Highway Research Program, documents state departments of transportation asset management practices for MSE walls in their inventories. Relevant practices include those related to maintenance and rehabilitation of deteriorated walls, inventory and assessment, and development of risk and life-cycle costs.
96 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99228-1
ISBN Ebook: 0-309-99229-X
DOI:
https://doi.org/10.17226/29115
National Academies of Sciences, Engineering, and Medicine. 2025. Asset Management Practices for Mechanically Stabilized Earth Walls. Washington, DC: The National Academies Press.
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Airport operators are seeing greater use of technology in their terminal concessions programs. This increased use reflects concessionaires using technology to improve efficiency, a growing customer preference for e-commerce, and airports leveraging their own technologies to better manage their commercial operations. Some airports have started to implement omnichannel ecommerce platforms to deliver an advanced retail experience for passengers.
ACRP Research Report 279: Framework and Tools for Incorporating Technologies into Airport In-Terminal Concessions Programs, from TRB's Airport Cooperative Research Program, presents a practical guide for evaluating, selecting, and implementing technology to enhance customer experience, operational efficiency, and revenue generation in airport terminal concessions programs.
Supplemental to the report are ACRP Web-Only Document 66: Incorporating Technologies into Airport In-Terminal Concessions Programs: A Primer, an Excel self-assessment tool, and a technical report on the research effort.
82 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99344-X
ISBN Ebook: 0-309-99345-8
DOI:
https://doi.org/10.17226/29145
National Academies of Sciences, Engineering, and Medicine. 2025. Framework and Tools for Incorporating Technologies into Airport In-Terminal Concessions Programs. Washington, DC: The National Academies Press.
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ACRP Web-Only Document 66: Incorporating Technologies into Airport In-Terminal Concessions Programs: A Primer, from TRB's Airport Cooperative Research Program, is supplemental to ACRP Research Report 279: Framework and Tools for Incorporating Technologies into Airport In-Terminal Concessions Programs. The primer is a practical document that will be of interest to a wide array of industry practitioners desiring to use technology to enhance airport terminal concessions programs.
77 pages
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8.5 x 11
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ISBN Ebook: 0-309-99348-2
DOI:
https://doi.org/10.17226/29146
National Academies of Sciences, Engineering, and Medicine. 2025. Incorporating Technologies into Airport In-Terminal Concessions Programs: A Primer. Washington, DC: The National Academies Press.
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State department of transportation (DOT) construction activities must comply with federal and state National Pollutant Discharge Elimination System construction general permit requirements. The regulations require state DOTs to implement policies, procedures, and practices to minimize offsite discharges of sediment-laden stormwater to protect downstream receiving water bodies during construction.
NCHRP Synthesis 648: Construction Stormwater Program Management, Tracking, Reporting, and Compliance, from TRB's National Cooperative Highway Research Program, documents state DOT practices, tools, and approaches for managing compliance with state and federal construction stormwater permit requirements.
188 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-73470-3
ISBN Ebook: 0-309-73471-1
DOI:
https://doi.org/10.17226/29051
National Academies of Sciences, Engineering, and Medicine. 2025. Construction Stormwater Program Management, Tracking, Reporting, and Compliance. Washington, DC: The National Academies Press.
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Traffic volume data are used by state departments of transportation (DOTs), metropolitan planning organizations (MPOs), and other local agencies in various analyses and functions related to transportation planning, design, traffic operations, safety, pavement design and maintenance, enforcement, environmental analysis, and construction, among others.
NCHRP Web-Only Document 436: Leveraging Existing Traffic Signal Assets to Obtain Quality Traffic Counts: A Guide, from TRB's National Cooperative Highway Research Program, provides transportation agencies with information about extracting motorized and non-motorized traffic volume data from existing signal assets.
89 pages
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8.5 x 11
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ISBN Ebook: 0-309-99517-5
DOI:
https://doi.org/10.17226/29214
National Academies of Sciences, Engineering, and Medicine. 2025. Leveraging Existing Traffic Signal Assets to Obtain Quality Traffic Counts: A Guide. Washington, DC: The National Academies Press.
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Severe weather events can impact transit agency operations, equipment, and infrastructure. For example, Hurricane Katrina in 2005 destroyed the transit fleet of the New Orleans Regional Transit Authority, more than 300 buses. In another example, an EF-4 tornado in 2021 destroyed the fleet of the Fulton County Transit Authority in Kentucky.
TCRP Synthesis 180: Transit Recovery in the Aftermath of Severe Weather Events: Current State of Practice, from TRB's Transit Cooperative Research Program, documents the current state of practice around transit recovery plans and provides examples of short- and long-term recovery. The focus is on bus operations in U.S. passenger public transportation systems, recognizing also that transit agencies may offer multiple types of services in addition to bus services, such as rail and light rail, streetcars or trolleys, paratransit, and ferry service.
108 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99392-X
ISBN Ebook: 0-309-99393-8
DOI:
https://doi.org/10.17226/29160
National Academies of Sciences, Engineering, and Medicine. 2025. Transit Recovery in the Aftermath of Severe Weather Events: Current State of Practice. Washington, DC: The National Academies Press.
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Supplementary cementitious materials (SCMs) are nonorganic additives used in concrete mixtures, either as a partial replacement of Portland cement in the mixture or as a preblended material with the cement. Commonly used SCMs include fly ash, slag cement, and silica fume. Due to the increasing unavailability of fly ash in many regions, state departments of transportation (DOTs) have been considering and using alternative SCMs.
NCHRP Synthesis 656: Use of Supplementary Cementitious Materials for Concrete, from TRB's National Cooperative Highway Research Program, documents state DOT practices for specifying and using SCMs in concrete.
144 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99319-9
ISBN Ebook: 0-309-99320-2
DOI:
https://doi.org/10.17226/29140
National Academies of Sciences, Engineering, and Medicine. 2025. Use of Supplementary Cementitious Materials for Concrete. Washington, DC: The National Academies Press.
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Culverts are buried drainage structures underneath roadways or embankments that are open at both ends and used to convey and transport water. They can often be vulnerable to accelerated deterioration when there is more frequent severe weather, which can lead to a suite of costly unplanned repairs, rehabilitation projects, or full replacements.
NCHRP Synthesis 651: Practices to Enhance Resiliency of Existing Roadway and Embankment Culverts, from TRB's National Cooperative Highway Research Program, documents management and maintenance practices used by state departments of transportation (DOTs) to enhance resiliency of existing roadway and embankment culverts.
154 pages
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8.5 x 11
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paperback
ISBN Paperback: 0-309-99294-X
ISBN Ebook: 0-309-99295-8
DOI:
https://doi.org/10.17226/29134
National Academies of Sciences, Engineering, and Medicine. 2025. Practices to Enhance Resiliency of Existing Roadway and Embankment Culverts. Washington, DC: The National Academies Press.
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