Developing a Guide for New Mobility Options in Travel Demand Forecasting and ModelingMay 27, 2024 The transportation field is undergoing a transformative change in response to several technological innovations resulting in the emergence and widespread adoption of new mobility options (NMOs) such as shared micromobility, transportation networking companies (TNCs), and connected and autonomous vehicles (CAVs). NCHRP Web-Only Document 399: Developing a Guide for New Mobility Options in Travel ...
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Impacts of Connected, Automated Vehicle Technologies on Traffic Incident Management ResponseMarch 15, 2024 Traffic Incident Management (TIM) is the process to detect, respond to, and clear traffic incidents so that traffic flow may be restored as safely and quickly as possible. Traffic incidents are unplanned events, such as crashes, that impact traffic flow, and TIM refers to the coordinated process to respond to and clear the incidents. NCHRP Web-Only Document 395: Impacts of Connected, Automated ...
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User’s Guide for Quantifying the Effects of Vehicle Mix on Crash Frequency and Crash SeverityFebruary 13, 2024 Heavy vehicle traffic and vehicle mix have a substantial impact on crash frequency and severity. The consideration of vehicle mix would improve predictive methods for crash frequency and severity. Improved methods will result in better use of the limited funds and resources available for improving the safety of the highway system and supporting performance-based approaches. NCHRP Web-Only Docum...
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Response Planning, Assessment, and Rapid Restoration of Service of Bridges in Extreme Events: Background and SummaryMay 16, 2024 Extreme events, such as hurricanes, tornados, floods, earthquakes, fires, and collisions, pose a threat to the transportation infrastructure that millions of people depend on daily. NCHRP Web-Only Document 390: Response Planning, Assessment, and Rapid Restoration of Service of Bridges in Extreme Events: Background and Summary , from TRB's National Cooperative Highway Research Program, sup...
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Ruggedness of Laboratory Tests to Assess Cracking Resistance of Asphalt MixturesDecember 1, 2023 Cracking and durability issues of asphalt pavements have been primary concerns of departments of transportation the last two decades. Several modes of asphalt pavement cracking exist—fatigue, top-down, reflective, and thermal—and all are influenced by thermal loading, traffic loading, or a combination of both. NCHRP Web-Only Document 389: Ruggedness of Laboratory Tests to Assess Cracking Resist...
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Framework for Implementing Constructability Throughout Project Development from NEPA to Final DesignDecember 22, 2023 Since the inception of using sets of plans for construction purposes, a persistent challenge has been the miscommunication between designers and constructors, even when they were part of the same organization. NCHRP Web-Only Document 388: Framework for Implementing Constructability Throughout Project Development from NEPA to Final Design , from TRB's National Cooperative Highway Research Progra...
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Safety Prediction Model for Freeway Facilities with High Occupancy LanesDecember 27, 2023 In an effort to relieve highway congestion and promote the movement of people, some state departments of transportation have modified their freeway facilities to include high occupancy vehicle lanes, high occupancy toll lanes (HOT, or HO lanes), and other managed lane strategies. NCHRP Web-Only Document 387: Safety Prediction Model for Freeway Facilities with High Occupancy Lanes , from TRB's N...
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Quantifying the Impacts of Corridor ManagementJanuary 26, 2024 Transportation corridors are defined by the infrastructure, services, and relationships connecting places. A corridor can be a national resource connecting large cities, a regional passage connecting a state’s trade centers, or local pathways connecting through a city or town. NCHRP Web-Only Document 386: Quantifying the Impacts of Corridor Management , from TRB's National Cooperative Highway R...
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Business Case and Communications Strategies for State DOT Resilience EffortsDecember 7, 2023 As transportation agencies face an increasing frequency and magnitude of risks, strategies and tools are essential for demonstrating, communicating, and gaining support for integrating resilience into transportation decisions and investments. NCHRP Web Only Document 385: Business Case and Communications Strategies for State DOT Resilience Efforts , from TRB's National Cooperative Highway Resear...
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Developing an Emergency Response Playbook for State Transportation AgenciesNovember 10, 2023 Transportation plays a crucial role before, during and after an emergency. Transportation agencies’ unique role stems from their broad range of capabilities and responsibilities. NCHRP Web-Only Document 384: Developing an Emergency Management Playbook for State Transportation Agencies , from TRB’s National Cooperative Highway Research Program, helps develop a playbook to support emergenc...
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Seismic Site Response Analysis with Pore Water Pressure Generation: Resources for EvaluationFebruary 16, 2024 There are many seismic site response analysis programs that operate in either the time domain or the frequency domain. These programs are available as public domain software, as commercial products, and/or through direct contact with the authors. NCHRP Web-Only Document 383: Seismic Site Response Analysis with Pore Water Pressure Generation: Resources for Evaluation , from TRB's National Cooper...
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Traffic Safety Culture: Conduct of Research ReportFebruary 5, 2024 Traffic safety culture is a complex topic spanning a range of sociological and philosophical concepts as they relate to transportation safety and the systemic framework that produces different kinds of traffic safety-related outcomes. NCHRP Web-Only Document 382: Traffic Safety Culture: Conduct of Research Report , from TRB's National Cooperative Highway Research Program, contributes to the bod...
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Developing Laboratory Methods and Specification Language to Test Tack Coat MaterialsNovember 15, 2023 Most asphalt pavement design methodologies assume pavements as monolithic structures composed of multiple layers to transfer the traffic loads on the surface to the bottom layers. However, this assumption is compromised when the pavement layers are not fully bonded. NCHRP Web-Only Document 381: Developing Laboratory Methods and Specification Language to Test Tack Coat Materials , from TRB's Nat...
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Accessing America's Great Outdoors: Forecasting Recreational Travel DemandOctober 26, 2023 Recreational travel is a major and growing activity in the United States. Recreation trips to outdoor parklands tend to have different characteristics than trips for other types of recreation, such as entertainment, sporting events, and regular exercise. NCHRP Web-Only Document 380: Accessing America's Great Outdoors: Forecasting Recreational Travel Demand , from TRB's National Cooperative High...
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Deploying Transportation Security Practices in State DOTsNovember 10, 2023 System-disrupting events, including those stemming from integrated cyber and physical components, intentional criminal acts, a global pandemic, accidents or unintentional human intervention, and natural causes, have only become more sophisticated since NCHRP Research Report 930: Update of Security 101: A Physical Security and Cybersecurity Primer for Transportation Agencies . NCHRP Web-Only Doc...
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Emergency Response: Organizational and Operational Models Used by State DOTsOctober 10, 2023 Large-scale emergencies and disasters (weather-related and other) may be somewhat rare but are not as rare as they used to be, and are generally increasing in intensity and frequency. How state departments of transportation (DOTs) train and coordinate prior to emergencies makes a big difference in how effectively they respond to an emergency. NCHRP Web-Only Document 378: Emergency Response: Org...
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Background and Development of a Guide for Intersection Control EvaluationFebruary 8, 2024 A variety of intersection control evaluation processes and metrics are used by highway agencies for evaluating intersection geometry and control options and identifying an optimal geometric and control solution for an intersection. These processes usually address safety, operational, multimodal, environmental, right-of-way, and cost impacts and other considerations. NCHRP Web-Only Document 377:...
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Rapid Tests and Specification Language for Construction of Asphalt-Treated Cold Recycled PavementsOctober 10, 2023 NCHRP Web-Only Document 376: Rapid Tests and Specification Language for Construction of Asphalt-Treated Cold Recycled Pavements , from TRB's National Cooperative Highway Research Program, provides the results and analysis of field testing conducted to verify the short-pin raveling test (SPRT) and long-pin shear test (LPST) threshold values recommended in NCHRP Research Report 960: Proposed AAS...
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Developing a Guide to Shared-Risk Insurance Pools for Transit Agencies: Conduct of Research ReportNovember 30, 2023 In states where there is a Transit Risk-Sharing Insurance Pool, state departments of transportation (DOTs) indicate cost reduction and access to insurance as the main objectives of the pools. Among pool benefits, transit agencies find that their insurance premiums were reduced by 15%, they are mostly satisfied with their pool services, and they participate in risk reduction programs. NCHRP Web-...
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Incorporating Maintenance Costs into a Transportation Asset Management PlanOctober 11, 2023 Since 2018, state departments of transportation (DOTs) have been required to develop risk-based transportation asset management plans (TAMPs) and to update these plans every four years. However, the absence of maintenance cost data in a TAMP prevents agencies from fully capturing the total investment made to preserve and improve highway infrastructure assets. NCHRP Web-Only Document 372: Incorp...
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Impact of New Disruptive Technologies on the Performance of DOTsOctober 11, 2023 Technology is at the core of the surface transportation system and is embodied in existing and new scientific knowledge and infrastructure, hardware, and software processes. It is designed to improve performance and cost-effectiveness of infrastructure and the vehicles, systems, and services that utilize the infrastructure. In recent years, a series of rapid advances in key technology areas suc...
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LTPP Data Analysis: Practical Tools and Procedures to Improve WIM Data QualityAugust 31, 2023 Highway agencies use weigh-in-motion (WIM) technology to collect vehicle weight and axle load data on roadways. NCHRP Web-Only Document 370: LTPP Data Analysis: Practical Tools and Procedures to Improve WIM Data Quality , from TRB's National Cooperative Highway Research Program, is a supplemental document to NCHRP Research Report 1070: Tools for Assuring WIM Data Quality: Practical Guide , and ...
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Estimating Effectiveness of Safety Treatments in the Absence of Crash DataOctober 4, 2023 The last decade has seen tremendous growth in resources available to state and local transportation agencies for conducting data-driven safety analysis. NCHRP Web-Only Document 369: Estimating Effectiveness of Safety Treatments in the Absence of Crash Data , from TRB's National Cooperative Highway Research Program, describes the process of developing a guide for using alternative, or surrogate,...
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Risk Assessment Techniques for Transportation Asset Management: AppendicesNovember 9, 2023 To effectively manage the condition and performance of transportation infrastructure, state transportation agencies must assess and manage risks to transportation assets. NCHRP Web-Only Document 366: Risk Assessment Techniques for Transportation Asset Management: Appendices , from TRB's National Cooperative Highway Research Program, presents the risk management resources summarized in NCHRP Res...
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Implementation of Life-Cycle Planning Analysis in a Transportation Asset Management FrameworkSeptember 18, 2023 Highway infrastructure assets are designed and built to serve long, useful lives. These assets undergo structural aging and degradation driven by traffic and environmental factors, natural and human hazards, and changes in demand and functional use. NCHRP Web-Only Document 365: Implementation of Life-Cycle Planning Analysis in a Transportation AssetManagement Framework , from TRB's National Coo...
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Construction Guidelines for Cold Central Plant Recycling and Cold In-Place RecyclingMarch 30, 2023 Cold In-place Recycling (CIR) and Cold Central Plant Recycling (CCPR) are two paving techniques that are experiencing increased use as agencies strive to find cost effective, sustainable solutions to rebuild the national roadway infrastructure without compromising performance. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 363: Construction Guidelines for Cold C...
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Pollinator Habitat Conservation Along Roadways, Volume 3: FloridaMay 25, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 3: Florida , from TR...
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Pollinator Habitat Conservation Along Roadways, Volume 4: Great BasinMay 25, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 4: Great Basin , fro...
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Pollinator Habitat Conservation Along Roadways, Volume 10: MidwestJune 9, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 10: Midwest , from TRB...
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Pollinator Habitat Conservation Along Roadways, Volume 15: Southern PlainsJune 23, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 15: Southern Plains , ...
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Pollinator Habitat Conservation Along Roadways, Volume 16: SouthwestJune 23, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 16: Southwest , from T...
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Pollinator Habitat Conservation Along Roadways, Volume 6: HawaiiJune 2, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 6: Hawaii , from TRB's...
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Pollinator Habitat Conservation Along Roadways, Volume 12: Northern PlainsJune 9, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 12: Northern Plains , ...
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Pollinator Habitat Conservation Along Roadways, Volume 11: NortheastJune 9, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 11: Northeast , from T...
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Pollinator Habitat Conservation Along Roadways, Volume 5: Great LakesJune 2, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 5: Great Lakes , from ...
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Pollinator Habitat Conservation Along Roadways, Volume 9: Mid-AtlanticJune 9, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 9: Mid-Atlantic , from...
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Pollinator Habitat Conservation Along Roadways, Volume 2: CaliforniaMay 25, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 2: California , from...
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Pollinator Habitat Conservation Along Roadways, Volume 1: AlaskaMay 25, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 1: Alaska , from TRB's...
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Pollinator Habitat Conservation Along Roadways, Volume 7: Inland NorthwestJune 2, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 7: Inland Northwest , ...
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Pollinator Habitat Conservation Along Roadways, Volume 8: Maritime NorthwestJune 2, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 8: Maritime Northwest ...
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Pollinator Habitat Conservation Along Roadways, Volume 14: SoutheastJune 23, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 14: Southeast , from T...
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Pollinator Habitat Conservation Along Roadways, Volume 13: Rocky MountainsJune 23, 2023 Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 13: Rocky Mountains , ...
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Acquisition of Utility Property Interests and Compensation Practices for Utility RelocationsJune 29, 2023 There is a need for guidance on how to acquire utility property interests and reimburse utility owners for eligible utility relocation costs. NCHRP Web-Only Document 360: Acquisition of Utility Property Interests and Compensation Practices for Utility Relocations , from TRB's National Cooperative Highway Research Program, develops guidelines that provide a framework for practitioners to follow ...
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Developing a Guide to Effective Methods for Setting Transportation Performance TargetsMay 19, 2023 Performance management has become increasingly important for transportation agencies in recent years. A key component of performance management is setting targets, which can be challenging. NCHRP Web-Only Document 358: Developing a Guide to Effective Methods for Setting Transportation Performance Targets , from TRB's National Cooperative Highway Research Program, is supplemental to NCHRP Resear...
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Wrong-Way Driving Solutions, Policy, and GuidelinesAugust 3, 2023 There are many strategies and treatments that agencies can consider for implementation to address wrong-way driving maneuvers, ranging from conventional traffic control devices to specialized geometric design elements and various intelligent transportation systems-based solutions. NCHRP Web-Only Document 357: Wrong-Way Driving Solutions, Policy, and Guidelines , from TRB's National Cooperative ...
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Development of a Guide for Accommodating Utilities within Highways and FreewaysApril 13, 2023 AASHTO is the author of two documents that have guided utility accommodation highways for decades. The first document primarily applies to utility accommodation on highways that are part of the Federal Aid system. The second document primarily applies to utilities on state highways. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 356: Development of a Guide for A...
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Safe and Effective Temporary Traffic Control for Mobile Operations on Two-Lane RoadwaysFebruary 3, 2023 Mobile operations can either move continuously along the roadway as during most striping operations, or intermittently as during a pothole patching operation. Mobile operations on two-lane roadways present unique challenges to transportation agencies, not the least of which is the highly variable conditions encountered in the field. The TRB National Cooperative Highway Research Program's NCHRP ...
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Risk-Based Inspection and Strength Evaluation of Suspension Bridge Main Cable SystemsJanuary 20, 2023 Most suspension bridges in use today have cables composed of thousands of steel wires and most of these bridges are aging and carry high volumes of traffic. Deterioration of the elements of the suspension system is a problem, replacement of these elements can be expensive and problematic, while failure could be catastrophic. The TRB National Cooperative Highway Research Program's NCHRP Web-Only...
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Crash Modification Factors in the Highway Safety Manual: Resources for EvaluationApril 20, 2023 Highway safety practitioners were given a significant new tool in 2010 with the publication of the AASHTO Highway Safety Manual . In the HSM, crash modification factors (CMFs) were provided to estimate the safety effects for a variety of treatments or countermeasures. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 352: Crash Modification Factors in the Highway S...
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Development and Application of Crash Severity Models for Highway Safety: Conduct of Research ReportMay 8, 2023 The first edition of the Highway Safety Manual has provided methods and procedures for estimating total crashes, crashes by type, and crashes by severity at the site level, project level and corridor level. Crash prediction models are critical in the entire safety management system recommended by HSM, including network screening, economic analysis, project prioritization, and safety effectivene...
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Long-Term Vegetation Management Strategies for Roadsides and Roadside AppurtenancesJanuary 26, 2023 Long-term vegetation management strategies that decrease the need for routine chemical and mechanical vegetation control can reduce recurring maintenance costs, highway worker exposure to traffic, impacts to the environment and cultural resources, and maintenance-related delays to the traveling public. However, these strategies vary in their effectiveness, longevity, initial construction costs,...
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Virtual Public Involvement: Lessons from the COVID-19 PandemicDecember 14, 2022 During the COVID-19 pandemic, transportation agencies' most used public-engagement tools were virtual public meetings, social media, dedicated project websites or webpages, email blasts, and electronic surveys. As the pandemic subsides, virtual and hybrid models continue to provide opportunities and challenges. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 349:...
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Macro-Level Analysis of Safety Planning and Crash Prediction Models: A GuideJune 21, 2023 The Highway Safety Manual (HSM) is a tool that helps transportation agencies make data-driven decisions about safety. It includes methods for quantifying safety performance and predicting crash frequencies. The HSM is currently being updated to include macro-level crash prediction models, which can be used to assess safety trends at a regional or national level. NCHRP Web-Only Document 348: Mac...
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Background and Summary of a Guide for RoundaboutsJune 1, 2023 Roundabout implementation in the United States has increased in the last decade, and practitioners have learned lessons in successfully applying roundabouts in various land use and transportation environments and contexts. Associated with NCHRP Research Report 1043: Guide for Roundabouts , which provides information and guidance on all aspects of roundabouts, the TRB National Cooperative Highwa...
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Programmatic Issues of Future System PerformanceNovember 18, 2022 State transportation agencies (STAs) may need to focus their strategic planning and programmatic initiatives over the next two decades to mitigate threats to, and take advantage of, opportunities for system performance and agency effectiveness. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 346: Programmatic Issues of Future System Performance details a unified ...
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State Transportation Agency Decision-Making for System Performance: Conduct of Research ReportMay 11, 2023 Transportation agencies must grapple with a broad range of trends and issues that influence and act upon the systems they manage and operate. Issues include climate change, goods movement, changing centers of population and economic activity, and telework, among others. NCHRP Web-Only Document 345: State Transportation Agency Decision-Making for System Performance: Conduct of Research Report , ...
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Risk-Based Construction Inspection: Conduct of Research ReportJune 9, 2023 Limited availability of construction-inspector resources for transportation infrastructure is a major challenge and can lead to accepting material or workmanship without sufficient examination, which can result in quality risks, safety concerns, functional failures, and reduced performance life of highway infrastructure. NCHRP Web-Only Document 344: Risk-Based Construction Inspection: Conduct o...
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Traffic Modeling DocumentMay 16, 2023 Freeway congestion usually occurs at freeway merge, diverge, and weaving segments that have the potential to develop bottlenecks. To alleviate or mitigate the impacts of congestion at these segments, a number of active management operational strategies have been implemented such as ramp metering, hard shoulder running, managed lanes, and others. The TRB National Cooperative Highway Research Pro...
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Roadway Cross-Section Reallocation: Conduct of Research ReportOctober 17, 2023 Trade-offs between uses of roadway cross sections are understood through a variety of lenses, from safety and operations to comfort and mode choice. Estimates of the impacts of cross-section decision-making on outcome measures include environmental, equity, and economy. NCHRP Web-Only Document 342: Roadway Cross-Section Reallocation: Conduct of Research Report , from TRB's National Cooperative ...
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Roadside Database Coding ManualJune 22, 2023 NCHRP Web-Only Document 341: Roadside Database Coding Manual , from TRB's National Cooperative Highway Research Program, is supplemental to NCHRP Research Report 1033: Long-Term Roadside Crash Data Collection Program . The document provides a coding manual for the NCHRP Project 17-43 database , a relational database that interfaces with the NASS CDS database, incorporating additional informati...
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Developing a Toolkit to Measure and Communicate the Value of Access ManagementApril 21, 2023 Access management has many benefits, including, but not limited to, improved safety, reduced delay, better multimodal quality of service, and livability. Yet government agencies often find themselves under intense pressure to yield to requests for more (or poorly located) access connections, or to forego a raised median that will preserve or restore roadway safety. The TRB National Cooperative ...
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Quantifying the Effects of Implements of Husbandry on Pavements: AppendicesDecember 1, 2022 Implements of husbandry (IoH) are vehicles designed for agricultural purposes and exclusively used in the conduct of agricultural operations. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 338: Quantifying the Effects of Implements of Husbandry on Pavements: Appendices is supplemental to NCHRP Research Report 1019: Quantifying the Effects of Impleme...
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Training and Certification of Construction Inspectors for Transportation InfrastructureJanuary 27, 2023 Construction inspectors (CIs) are the frontline workforce that ensures the work on transportation infrastructure projects meets the design and contract requirements and that the finished product meets or exceeds the quality standards. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 337: Training and Certification of Construction Inspectors for Transportation Infr...
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Proposed Guidelines for Fixed Objects in the Roadside Design GuideOctober 19, 2022 Crash data show that more than 18,000 traffic fatalities per year result from roadway departures, and over 7,000 of those roadway departure crashes involved collisions with roadside fixed objects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 336: Proposed Guidelines for Fixed Objects in the Roadside Design Guide helps develop an evaluation methodology and desi...
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A Guide to Computation and Use of System-Level Valuation of Transportation AssetsJune 8, 2022 Determining the value of a transportation organization's physical assets is important for both financial reporting and transportation asset management (TAM). The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 335: A Guide to Computation and Use of System-Level Valuation of Transportation Assets details how to calculate asset value and use it to support application i...
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Multi-State In-Service Performance Evaluations of Roadside Safety HardwareSeptember 29, 2022 The evolution of roadside hardware in the past has been largely dictated by changes to crash testing guidelines rather than observed field performance. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 332: Multi-State In-Service Performance Evaluations of Roadside Safety Hardware develops a unified format and nationally compatible "in-service performance evaluatio...
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Mobility on Demand and Automated Driving Systems: A Framework for Public-Sector AssessmentDecember 6, 2022 Innovative and emerging mobility services offer travelers more options to increase mobility and access goods and services. In addition, various technological developments have the potential to alter the automotive industry and traveler experience, as well as mobility and goods access. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 331: Mobility on Demand and Aut...
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Accessibility Measures in PracticeNovember 3, 2022 With an accessibility perspective, land use changes can bring transportation improvements by bringing activity locations closer together. If incorporated into transportation performance management, accessibility has the potential to highlight projects that would otherwise be overlooked because of their congestion-related impacts. The TRB National Cooperative Highway Research Program's NCHRP Web...
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Bonded Concrete Overlays on Asphalt Pavements: Resources for EvaluationOctober 13, 2022 The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 329: Bonded Concrete Overlays on Asphalt Pavements: Resources for Evaluation provides Appendices A through G of the contractor’s final report, which detail survey responses from transportation agencies on bonded concrete overlays on asphalt pavements as well as agency plans and projects. The document is supple...
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Safety Effects of Raising Speed Limits to 75 mph and HigherOctober 17, 2022 Across the United States, maximum speed limit laws vary dramatically. In the mid-1990s, many states increased speed limits to 75 mph on select roads. More recently, some states have established speed limits greater than 75 mph. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 328: Safety Effects of Raising Speed Limits to 75 mph and Higher is supplemental to NCHRP...
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Serious and Fatal Motorcycle Crashes into Traffic Barriers: Injury InformationOctober 27, 2022 Motorcycle riders account for more fatalities than the passengers of any other vehicle type involved in a guardrail collision. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 327: Serious and Fatal Motorcycle Crashes into Traffic Barriers: Injury Information is a supplemental document to NCHRP Research Report 1005: Motorcycle Crashes into Traffic Barriers: Factor...
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Consideration of Roadside Features in the Highway Safety ManualMay 2, 2022 Highway engineers are constantly redesigning and rebuilding roadways to meet higher standards, provide safer highways and increase mobility. For the last forty years this has included designing and building roadways that are more forgiving when a driver inadvertently encroaches onto the roadside. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 325: Consideration ...
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Guide to Implementation of the Toward Zero Deaths National Strategy on Highway SafetyJune 27, 2022 In June 2014, eight associations that represent government agencies involved in highway safety released the document Toward Zero Deaths: A National Strategy on Highway Safety . This national strategy describes a long-term vision of zero traffic-related deaths and outlines the current challenges that need to be tackled. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Docum...
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Highway Safety Manual User GuideMarch 31, 2022 The Highway Safety Manual can be used to identify sites with the most potential for crash frequency or severity reduction; identify contributing factors to crashes and mitigation measures; and estimate the potential crash frequency and severity on highway networks, among other uses. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 323: Highway Safety Manual User G...
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Command-Level Decision Making for Transportation Emergency ManagersMay 16, 2022 Command-level decision making is a critical factor in successfully managing and mitigating critical incidents. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 321: Command-Level Decision Making for Transportation Emergency Managers is a document done in collaboration with TRB's Transit Cooperative Research Program (TCRP) and Airport Cooperative Research Pro...
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Aligning Geometric Design with Roadway ContextMarch 21, 2022 Since 1984, AASHTO’s “Green Book” and other roadway design criteria have been primarily based on a functional classification system of a hierarchical network composed of arterials, collector, and local roads. However, this hierarchical functional classification system is in lack of flexibility in design, especially for a modern multimodal roadway system. The TRB National Cooperative Highwa...
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Roadside Safety Analysis Program (RSAP) UpdateMarch 11, 2022 Motor vehicle crashes cost society more than $230 billion annually. On an average day, 117 fatal crashes occur on U.S. roadways, and 30 percent of these fatalities are people under the age of 25. In total, this amounts to a societal loss of $630 million per day. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 319: Roadside Safety Analysis Program (RSAP) Update de...
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Safety Prediction Models for Six-Lane and One-Way Urban and Suburban ArterialsMarch 10, 2022 The Highway Safety Manual (HSM) provides a predictive method for two- and four-lane urban and suburban arterial facilities with both undivided and divided cross-sections. The manual does not cover arterials with six or more lanes or one-way streets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 318: Safety Prediction Models for Six-Lane and One-Way Urban and Su...
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Developing a Guide for Managing Performance to Enhance Decision-MakingJune 9, 2022 Transportation agencies largely have performance structures in place, but these structures alone do not guarantee progress on meeting performance targets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 317: Developing a Guide for Managing Performance to Enhance Decision-Making provides guidance on how agencies can strengthen their gathering and use of feedback t...
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Human Factors Guidelines for Road Systems 2021 Update, Volume 2: Conduct of Research Report January 27, 2022 Human factors principles and concepts can be used by highway designers and traffic engineers to improve roadway design and traffic safety. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 316: Human Factors Guidelines for Road Systems 2021 Update, Volume 2: Conduct of Research Report describes the process of updating guidelines, which were delivered in NCHRP Web-O...
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Human Factors Guidelines for Road Systems 2021 Update, Volume 1: Updated and New ChaptersJanuary 27, 2022 In 2015, there were more than 6 million police-reported crashes in the United States. While crashes are complex and it is generally interactions between road users, vehicles, and the environment that lead to crashes, some form of driver error is a contributing factor in most crashes. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 316: Human Factors Guidelines fo...
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Details of the Study on the Use of 0.7-in Diameter Strands in Precast Pretensioned GirdersAugust 3, 2022 The use of precast pretensioned girders using 0.7-in. diameter strands would help bridge designers extend the spans of the existing girder shapes. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 315: Details of the Study on the Use of 0.7-in Diameter Strands in Precast Pretensioned Girders is supplemental to NCHRP Research Report 994: Use of 0.7-in. Diameter Stra...
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Updating the AASHTO LRFD Movable Highway Bridge Design SpecificationsNovember 5, 2021 There are approximately 1,000 movable highway bridges in the U.S. inventory. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 314: Updating the AASHTO LRFD Movable Highway Bridge Design Specifications allows bridge owners the option of employing site-specific conditions to develop the design wind speed and provides other general updates to previous research from 2...
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Selecting Ramp Design Speeds, Volume 2: Conduct of Research ReportNovember 23, 2021 Designing extended sections of highway based on the design speed process is relatively straightforward. However, when applied to interchange ramps where high-speed facilities meet low-speed facilities and drivers are expected to accelerate or decelerate over short distances, application of the design speed process is more complex. The TRB National Cooperative Highway Research Program's NCHRP We...
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Selecting Ramp Design Speeds, Volume 1: GuideNovember 23, 2021 Selection of a design speed should be based upon the anticipated operating speed, topography, adjacent land use, modal mix, and functional classification of the roadway. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 313: Selecting Ramp Design Speeds, Volume 1: Guide provides further detail for selecting an appropriate ramp design speed than presented in the 201...
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Evaluation and Synthesis of Connected Vehicle Communication TechnologiesOctober 13, 2021 In 1999, the Federal Communications Commission (FCC) allocated the intelligent transportation system (ITS) band, also known as the “5.9 GHz band,” for transportation purposes including connected and automated vehicle (CAV) technologies. These technologies enable a host of applications for vehicle‐to-vehicle, vehicle‐to‐infrastructure, and vehicle‐to‐pedestrian communication — collectively known...
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Safety Performance of Part-Time Shoulder Use on Freeways, Volume 2: Conduct of Research Report November 5, 2021 Part-time shoulder use is a congestion relief strategy that allows use of the left or right shoulders as travel lanes during some, but not all, hours of the day. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 309: Safety Performance of Part-Time Shoulder Use on Freeways, Volume 2: Conduct of Research Report describes the development of crash predicti...
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Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation SectorMarch 14, 2022 Many technical and institutional issues related to estimating and reducing greenhouse gas emissions (GHGs) lie across a wide spectrum of the activities undertaken by state departments of transportation (DOTs). The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 308: Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector documents the...
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Recommended Guidelines for the Selection of Test Levels 2 Through 5 Bridge RailingsSeptember 27, 2021 Since bridges cross over large spans of space they often cross significant features such as busy transportation corridors. In addition, bridges carry heavy vehicles sometimes with dangerous cargos, such as fuel and hazardous chemicals. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 307: Recommended Guidelines for the Selection of Test Levels 2 Through 5 Bridge R...
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Safety Prediction Methodology and Analysis Tool for Freeways and InterchangesOctober 11, 2021 Prior to this research project, state highway agencies did not have tools for reflecting safety in their decisions concerning freeway and interchange projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 306: Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges documents a safety prediction method for freeways that is suitable for inc...
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Validation of a Performance-Based Mix Design Method for Porous Friction CoursesSeptember 15, 2021 Porous Friction Course (PFC) mixtures are designed with an open aggregate structure to yield high inplace air voids (i.e., typically between 15 and 20 percent). This allows rainwater to drain horizontally through the layer toward the edge of the pavement structure, thereby improving pavement surface friction. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 305: V...
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Criteria for Restoration of Longitudinal Barriers, Phase II August 27, 2021 Guardrails are an important feature of the roadside that are used to shield errant motorists from becoming involved in even more catastrophic crashes by redirecting vehicles away from fixed hazards such as trees and poles and terrain hazards such as steep roadside slopes and fill embankments. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 304: Criteria for Resto...
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Understanding and Communicating Reliability of Crash Prediction ModelsDecember 16, 2021 Understanding and communicating consistently reliable crash prediction results are critical to credible analysis and to overcome barriers for some transportation agencies or professionals utilizing these models. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 303: Understanding and Communicating Reliability of Crash Prediction Models provides guidance on being ab...
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Development of Guidelines for Quantifying Benefits of Traffic Incident Management StrategiesFebruary 4, 2022 Traffic Incident Management activities have advanced in recent years to become a critical part of transportation operations, as well as a significant budget expenditure. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 301: Development of Guidelines for Quantifying Benefits of Traffic Incident Management Strategies seeks to improve uniformity in measurement, acces...
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Guidance to Predict and Mitigate Dynamic Hydroplaning on RoadwaysJuly 29, 2021 Hydroplaning is a serious problem that is associated with a relatively small but significant number of crashes. Statistics from various parts of the world indicate that approximately 15% to 20% of all road traffic crashes occur in wet weather conditions. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 300: Guidance to Predict and Mitigate Dynamic Hydroplaning on ...
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Investigating the Relationship of As-Constructed Asphalt Pavement Air Voids to Pavement PerformanceJune 11, 2021 Several controlled laboratory studies have shown that air voids (AV) can have a large effect on the performance of asphalt pavements. AVs that are either too high or too low can cause a reduction in pavement life. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 299: Investigating the Relationship of As-Constructed Asphalt Pavement Air Voids to Pavement Performanc...
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Developing a Systematic Approach for Determining Construction Contract TimeMarch 18, 2022 Excessive contract time is costly because it extends a construction crew’s exposure to traffic, prolongs the inconvenience to the public, and subjects motorists to less than desirable safety conditions for longer periods. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 298: Developing a Systematic Approach for Determining Construction Contract Timeseeks to provid...
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Intersection Crash Prediction Methods for the Highway Safety ManualApril 11, 2021 The first edition of the Highway Safety Manual (HSM), in 2010, included Safety Performance Functions (SPFs) for roadway segments and intersections. However, not all intersection types are covered in the first edition of the HSM. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 297: Intersection Crash Prediction Methods for the Highway Safety Manual develops ...
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Guidelines for Cost-Effective Safety Treatments of Roadside DitchesApril 2, 2021 Run-off-road traffic crashes account for almost one-third of the deaths and serious injuries each year on U.S. highways. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 296: Guidelines for Cost-Effective Safety Treatments of Roadside Ditches provides new proposed design guidance for the configuration of ditches adjacent to the roadway. A supplemental PowerPoint S...
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Improved Prediction Models for Crash Types and Crash SeveritiesApril 29, 2021 The release of the Highway Safety Manual (HSM) by the American Association of State Highway and Transportation Officials (AASHTO) in 2010 was a landmark event in the practice of road safety analysis. Before it, the United States had no central repository for information about quantitative road safety analysis methodology. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Do...
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Revised Clear-Water and Live-Bed Contraction Scour Analysis Training ManualJuly 16, 2021 A workshop, "Revised Contraction Scour Analysis," is presented in this training manual. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 294: Revised Clear-Water and Live-Bed Contraction Scour Analysis Training Manual adheres to the guidance promulgated by the National Highway Institute and the International Association of Continuing Education and Training for adu...
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Deploying Transportation Resilience Practices in State DOTsJune 24, 2021 Over the past 15 years, the nation’s transportation systems have experienced numerous significant disruptions that have resulted in economic loss and loss of human life. The 2020 COVID-19 pandemic is a recent example of how unexpected events can affect the performance and role of transportation systems. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 293: Deployi...
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Roadside Hardware Replacement Analysis: User GuideFebruary 11, 2021 Highway agencies can use a method to assess roadside hardware and establish priorities on how upgrades of hardware should occur for individual projects or establish policy guidelines on roadside hardware assessments. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 292: Roadside Hardware Replacement Analysis: User Guide presents how to implement and plan for asses...
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Development of a Posted Speed Limit Setting Procedure and ToolJune 4, 2021 Several types of speed limits exist, including statutory speed limit, posted speed limit, school zone speed limit, work zone speed limit, variable speed limit, and advisory speed. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 291: Development of a Posted Speed Limit Setting Procedure and Tool documents the research efforts and findings from an NCHRP Project 17-...
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Highway Capacity Manual Methodologies for Corridors Involving Freeways and Surface StreetsOctober 19, 2020 The procedures detailed in the 6th Edition of the Highway Capacity Manual (HCM) estimate capacity and several operational measures, including those determining Level of Service, for freeway facilities as well as surface streets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 290: Highway Capacity Manual Methodologies for Corridors Involving Freeways and Surface ...
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Standard Definitions for Common Types of Pavement CrackingSeptember 16, 2020 New definitions will help pavement cracking survey providers and pavement engineers at state highway administrations conduct objective cracking measurements and encourage continuing technological innovations by researchers and vendors. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 288: Standard Definitions for Common Types of Pavement Cracking helps develop sta...
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Planning and Implementing Multimodal, Integrated Corridor Management: GuidebookAugust 18, 2020 Integrated Corridor Management (ICM) is an operational concept that seeks to reduce congestion and improve performance by maximizing the use of available multimodal capacity across a corridor, including highways, arterial roads, and transit systems. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 287: Planning and Implementing Multimodal, Integrated Corridor Mana...
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Principles and Guidance for Presenting Active Traffic Management Information to DriversMarch 5, 2021 Active Traffic Management (ATM) strategies have become more common in the United States as state departments of transportation grapple with increasing congestion and fewer dollars available to add capacity to keep pace. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 286: Principles and Guidance for Presenting Active Traffic Management Information to Drivers deve...
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Developing a Guide for Quantitative Approaches to Systemic Safety AnalysisDecember 14, 2020 Highway agencies have traditionally managed the safety improvement process by identifying and correcting high-crash locations (“hot-spots”), where concentrations of crashes and, often, patterns of crashes of similar types, were found. However, when crashes are evaluated over too short a period of time (3 years or less), locations may be identified as hot-spots simply due to the random nature of...
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Decision-Making Guide for Traffic Signal PhasingAugust 17, 2020 Few resources provide information related to selecting the most appropriate traffic signal phasing for the various geometric and operational situations encountered in the field. This is especially true for left-turn signal phasing decisions with respect to the level of control for the left-turn movement and whether left turns should precede or follow the main through movement. The TRB National ...
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Improving Mid-Term, Intermediate, and Long-Range Cost Forecasting for State Transportation AgenciesOctober 28, 2020 Predicting the future of the construction market is always a challenging task - regardless of whether it is over the next one or 20 years - since it involves several uncertainties. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 283: Improving Mid-Term, Intermediate, and Long-Range Cost Forecasting for State Transportation Agencies documents the research that led...
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Framework for Managing Data from Emerging Transportation Technologies to Support Decision-MakingOctober 21, 2020 The amount of data surrounding the application of emerging technologies is expanding, producing “big data” at magnitudes not previously seen. While a few agencies have found some success with individual projects, most are uncertain on how to handle this level of big data at an organizational level. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 282: Framework fo...
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Integrating Tribal Expertise into Processes to Identify, Evaluate, and Record Cultural ResourcesApril 7, 2020 There is a lot of evidence that Native American tribes could be better involved in planning transportation projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 281: Integrating Tribal Expertise into Processes to Identify, Evaluate, and Record Cultural Resources explores how unique tribal perspectives and expertise could inform the tribal engagement and consu...
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Valuing Wildlife Crossings and Enhancements for Mitigation CreditsFebruary 27, 2020 There is mounting evidence demonstrating the effectiveness of wildlife overpasses and underpasses in improving motorist safety and conserving wildlife. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 280: Valuing Wildlife Crossings and Enhancements for Mitigation Credits synthesizes current practices used by state DOTs and their partners for calculating and apply...
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Information Findability Implementation Pilots at State Transportation AgenciesJuly 28, 2020 With a quick online search, you can discover the answers to all kinds of questions. Findability within large volumes of information and data has become almost as important as the answers themselves. Without being able to search various types of media ranging from print reports to video, efforts are duplicated and productivity and effectiveness suffer. The TRB National Cooperative Highway Resear...
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Implementing Alternative Technical Concepts in All Types of Highway Project Delivery MethodsJuly 13, 2020 There is an emerging view in the construction industry that better performance or better value for money can be achieved by integrating teamwork for planning, design, and construction of projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 277: Implementing Alternative Technical Concepts in All Types of Highway Project Delivery Methods seeks to assist integr...
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Evaluating Strategies for Work Zone Transportation Management PlansSeptember 18, 2020 Transportation management plans (TMPs) are a set of coordinated strategies designed to help agencies achieve work zone project goals related to traffic mobility, efficient system operation, motorist and worker safety, and other operational targets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 276: Evaluating Strategies for Work Zone Transportation Management P...
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Zero Emission Vehicles: Forecasting Fleet Scenarios and their Emissions ImplicationsFebruary 1, 2020 Vehicle electrification is one of the emerging and potentially disruptive technologies that are being considered to reduce emissions of criteria pollutants, mobile source air toxics (MSATs), and greenhouse gases (GHGs) from motor vehicles. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 274: Zero Emission Vehicles: Forecasting Fleet Scenarios and their Emissions ...
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Road User Understanding of Bicycle Signal Faces on Traffic SignalsJanuary 6, 2020 Prior to 2013, the use of bicycle-specific signals in the U.S. was limited to a few jurisdictions. However, in recent years, the number of installations has grown rapidly. This research identified more than 500 intersections using bicycle signals in a variety of contexts. Despite the recent approval and practice, the TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 27...
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Existing and Emerging Highway Infrastructure Preservation, Maintenance, and Renewal Definitions, Practices, and ScenariosApril 23, 2020 The National Cooperative Highway Research Program's NCHRP Web-Only Document 272: Existing and Emerging Highway Infrastructure Preservation, Maintenance, and Renewal Definitions, Practices, and Scenarios provides appendices to NCHRP Report 750, Volume 7: Preservation, Maintenance, and Renewal of Highway Infrastructure .
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Guide Specification for Service Life Design of Highway BridgesJanuary 3, 2020 The majority of instances of explicit consideration of service life design has been limited to signature bridges and other projects where extended service lives (in other words, greater than 100 years) are specified by the owner. Many state departments of transportation and other transportation agencies have recognized the importance of implementing service life design for typical highway bridg...
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Developing a Guide to Emergency Management at State Transportation AgenciesJuly 22, 2020 Transportation plays a critical role in emergency management. After all, state transportation agencies have large and distributed workforces, easy access to heavy equipment, and a robust communications infrastructure capable of sustained mobilization. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 267: Developing a Guide to Emergency Management at State Transpor...
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Developing a Physical and Cyber Security Primer for Transportation Agencies July 17, 2020 Small events pose threats of great consequences since the impact of any incident is magnified when a transportation network is operating at or past its capacity—as is the case in portions of many states as travel demand on their transportation networks grows. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 266: Developing a Physical and Cyber Security Primer for ...
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White Papers for Right-Sizing Transportation InvestmentsSeptember 4, 2020 While not all right-sizing projects involve a change in jurisdictional responsibility and ownership, jurisdictional transfer can be a key tool for implementing right-sizing plans and agreements. As a supplemental document to NCHRP Research Report 917: Right-Sizing Transportation Investments:A Guidebook for Planning and Programming , the TRB National Cooperative Highway Research Program's NCHRP ...
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Sustainable Highway ConstructionJanuary 31, 2020 A programmatic approach to sustainable materials procurement in highway construction may be better than one-off attempts. For now, there is little guidance on procuring sustainability in highway construction and sustainability is not as important as cost or schedule. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 262: Sustainable Highway Construction describes t...
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Case Studies of Truck Activity Data for Emissions Modeling June 12, 2019 NCHRP Web-Only Document 261: Case Studies of Truck Activity Data for Emissions Modeling consists of seven case studies that are appendices A to G of NCHRP Report 909: Guide to Truck Activity Data for Emissions Modeling. NCHRP Research Report 909 explores methods, procedures, and data sets needed to capture commercial vehicle activity, vehicle characteristics, and operations to assist in estimat...
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Guidelines to Improve the Quality of Element-Level Bridge Inspection DataMarch 8, 2019 TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 259: Guidelines to Improve the Quality of Element-Level Bridge Inspection Data is intended to assist inspectors in identifying defects and assigning the appropriate condition state for bridge elements. To ensure the safety and serviceability of bridges, the guidelines include accuracy requirements designed to help pro...
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Manual on Subsurface InvestigationsFebruary 6, 2019 TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 258: Manual on Subsurface Investigations provides an update to the American Association of State Highway Transportation Officials (AASHTO) 1988 manual of the same name. This report reflects the changes in the approaches and methods used for geotechnical site characterization that the geotechnical community has develop...
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A Mechanistic–Empirical Model for Top–Down Cracking of Asphalt Pavements LayersOctober 31, 2018 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...
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Assessing Interactions Between Access Management Treatments and Multimodal Users December 28, 2018 TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 256: Assessing Interactions Between Access Management Treatments and Multimodal Users describes operational and safety relationships between access management techniques and the automobile, pedestrian, bicycle, public transit, and truck modes. This contractor's report may help assist in the selection of alternati...
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Improved Analysis of Two-Lane Highway Capacity and Operational PerformanceJuly 2, 2018 TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 255: Improved Analysis of Two-Lane Highway Capacity and Operational Performance supplements the sixth edition of the Highway Capacity Manual (HCM). Specifically, this project includes the following updates: the development of a more realistic speed-flow relationship the introduction of a new service measure—follower d...
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Implications of Connected and Automated Driving Systems, Vol. 6: Implementation PlanOctober 26, 2018 TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 6: Implementation Plan provides a technical memorandum on how to put the research findings and products into practice; identifies possible institutions that might take leadership in applying the research findings/products; and identifies issues affecti...
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