 Guidelines for Treatments to Mitigate Opposite Direction CrashesMay 16, 2022 From 2016 through 2018, there were more than 19,200 vehicles in the United States involved in opposite direction crashes that resulted in a fatality. Approximately 68 percent of these crashes occurred on two-lane roadways. The TRB National Cooperative Highway Research Program's NCHRP Research Rep...
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 Guide to Pedestrian AnalysisFebruary 18, 2022 Roadway designs and signal phasing that address the safety of all road users are being implemented in many cities around the country. As part of this, accurate methods for estimating pedestrian volumes are needed to quantify exposure and, in turn, evaluate the benefits of pedestrian safety measur...
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 Guidelines for the Development and Application of Crash Modification FactorsNovember 17, 2021 Crash modification factors (CMF) provide transportation professionals with the kind of quantitative information they need to make decisions on where best to invest limited safety funds. The TRB National Cooperative Highway Research Program's pre-publication draft of NCHRP Research Report 991: Gui...
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 Rural Transportation Issues: Research RoadmapSeptember 27, 2021 Although only 19% of the population lives in rural areas, more than 70% of the U.S.’s four million miles of roadways are in rural areas. The rural transportation system also includes numerous airports; railways; inland and coastal waterways; rural and intercity buses; and bicycle, pedestrian, and...
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 Ruggedness of Laboratory Tests for Asphalt Mixture Cracking ResistanceMarch 16, 2022 Cracking is a primary distress mode of asphalt pavements that creates the need for their rehabilitation. All types of asphalt pavement cracking—thermal, reflection, fatigue, and topdown— are affected by numerous factors and their interactions. The TRB National Cooperative Highway Research Program...
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 Implementation of the AASHTO Guide for Enterprise Risk ManagementMarch 8, 2022 The AASHTO Guide for Enterprise Risk Management , published in 2016, defines enterprise risk management as “the formal and systematic effort to control uncertainty and variability on an organization’s strategic objectives by managing risks at all levels of the organization.” The TRB National Coop...
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 Guidelines for Quantifying Benefits of Traffic Incident Management StrategiesFebruary 4, 2022 Ensuring a coordinated response to highway crashes and other incidents is vital to protecting public safety, keeping traffic moving, and reducing environmental impacts. The TRB National Cooperative Highway Research Program's NCHRP Research Report 981: Guidelines for Quantifying Benefits of Traffi...
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 Systematic Approach for Determining Construction Contract Time: A GuidebookMarch 18, 2022 Contract time affects the cost of construction, traffic disruption and public inconvenience, the economic impact of projects to the surrounding areas, and schedule risks. The TRB National Cooperative Highway Research Program's NCHRP Research Report 979: Systematic Approach for Determining Constru...
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 Access Management in the Vicinity of Interchanges, Volume 2: Research OverviewFebruary 15, 2022 The spacing of crossroads in the vicinity of interchanges can have operational and safety impacts on a street system. The deployment of access management strategies in these areas can also have potential influence on the economic vitality of a roadway network, but how best to balance these critic...
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 Resilience Primer for Transportation ExecutivesAugust 6, 2021 CEOs of departments of transportation (DOTs) face many challenges, including some that will have serious impacts on people's mobility and safety, and possibly on the tenure of CEOs. Many of these challenges revolve around the resilience of the transportation system—how well it can withstand disru...
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 Transportation System Resilience: Research Roadmap and White PapersSeptember 24, 2021 Although the need for a more effective set of short- and long-term transportation resilience strategies is increasingly obvious and urgent, many knowledge gaps and institutional barriers still exist. The TRB National Cooperative Highway Research Program's NCHRP Research Report 975: Transportation...
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 Revised Clear-Water and Live-Bed Contraction Scour AnalysisJuly 16, 2021 Bridge waterways commonly narrow or constrict natural channels, forcing water to flow through a contracted area, thereby increasing the magnitudes of velocity and turbulent kinetic energy of flow passing through the waterway. If these increases cause erosion of the waterway boundaries, the contra...
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 Mainstreaming System Resilience Concepts into Transportation Agencies: A GuideJune 24, 2021 Transportation officials recognize that a reliable and sustainable transportation system is needed to fulfill their agency’s mission and goals. The TRB National Cooperative Highway Research Program's NCHRP Research Report 970: Mainstreaming System Resilience Concepts into Transportation Agencies:...
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 Traffic Signal Control Strategies for Pedestrians and BicyclistsFebruary 9, 2022 In the United States, traffic signal timing is traditionally developed to minimize motor vehicle delay at signalized intersections, with minimal attention paid to the needs of pedestrians and bicyclists. The unintended consequence is often diminished safety and mobility for pedestrians and bicycl...
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 LED Roadway Lighting: Impact on Driver Sleep Health and AlertnessJuly 29, 2021 Light emitting diode (LED) technology has revolutionized the lighting industry. The dimming and instant-on capabilities of these light sources along with their high efficiency have allowed lighting designers to overcome some of the limitations of previous technologies, particularly in roadway lig...
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 Asphalt Binder Aging Methods to Accurately Reflect Mixture AgingApril 30, 2021 Asphalt binders experience aging that occurs in two distinct stages under quite different conditions: (1) short-term during construction (plant mixing, storage, placement, and compaction) and (2) long-term during the service life of the pavement. The TRB National Cooperative Highway Research Prog...
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 Posted Speed Limit Setting Procedure and Tool: User GuideJune 4, 2021 Several factors are considered within engineering studies when determining the posted speed limit, including the 85th percentile speed, which is based on the driving behavior of most drivers (85 percent). The 85th percentile speed is believed to represent a safe speed that would minimize crashes....
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 Protocols for Network-Level Macrotexture MeasurementJune 21, 2021 Macrotexture, which influences vehicle-roadway skid resistance, refers to the texture of the pavement due to the arrangement of aggregate particles. Pavement surfaces are subjected to seasonal variations, and over time the embedded aggregates become polished due to the onslaught of traffic. Resea...
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 A Pandemic Playbook for Transportation AgenciesApril 12, 2021 Understanding pandemics, their impacts to transportation, and potential effective response has become more important, not only for the response to COVID-19, but also if, as the World Health Organization warns, we are now “living in a time of viruses.” TRB's National Cooperative Highway Research P...
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 Proposed Modification to AASHTO Cross-Frame Analysis and DesignFebruary 8, 2021 Cross-frames are important structural components that serve many functions throughout the service life of steel I-girder bridges. Under repetitive load cycles caused by heavy truck passages, cross-frames and their connections can be susceptible to load-induced fatigue cracking if not properly des...
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 Entrained Air-Void Systems for Durable Highway ConcreteFebruary 3, 2021 Laboratory testing and field experience have shown that highway concrete should be properly air entrained to resist the action of freezing and thawing, particularly in wet climates. Several gaps in the state of the knowledge still exist. The TRB National Cooperative Highway Research Program's NCH...
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 Diverging Diamond Interchange Informational Guide, Second EditionJanuary 29, 2021 The diverging diamond interchange (also known as a double crossover diamond interchange) is a relatively new design to the United States. This design can increase throughput and safety without widening bridge structures. The TRB National Cooperative Highway Research Program's NCHRP Research Repo...
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 Utilization Measurement and Management of Fleet EquipmentJanuary 29, 2021 State highway agency equipment fleet assets are vital to the delivery of agency programs, projects, and services. Measuring, monitoring, and reporting on asset utilization levels are necessary for the management of the equipment fleet and meeting the highway agency’s business needs. The TRB Natio...
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 Guidebook for Data and Information Systems for Transportation Asset ManagementMarch 26, 2021 Effective transportation asset management (TAM) depends on having good data about the assets under management, their descriptions, current condition and history, functional performance, and the activities conducted to develop, maintain, improve, and rehabilitate them during the course of their se...
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