 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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 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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 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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 Guide for Quantitative Approaches to Systemic Safety AnalysisDecember 14, 2020 Traditional approaches to safety have focused on identifying high-crash locations and implementing projects to address predominant concerns at these locations. The systemic approach to safety is a method of safety management that typically involves lower unit cost safety improvements that are wid...
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 Performance-Based Management of Traffic SignalsDecember 31, 2020 Management of traffic signal systems is a critical function for many transportation agencies. Thanks to advancements in technology, it is now possible to collect large amounts of data at signalized intersections, leading to the development of dozens of performance measures. The TRB National...
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 Guidebook for Managing Data from Emerging Technologies for TransportationOctober 21, 2020 With increased connectivity between vehicles, sensors, systems, shared-use transportation, and mobile devices, unexpected and unparalleled amounts of data are being added to the transportation domain at a rapid rate, and these data are too large, too varied in nature, and will change too quickly ...
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 AASHTO Load Rating Provisions for Implements of HusbandryNovember 20, 2020 Farm equipment, generally referred to as “implements of husbandry” (IoH), has been considered to be local vehicles on farms that do not use public roads often, if at all. As a result, state and local jurisdictions vary widely in managing IoH. Apparently, the growth of IoH has far outpaced that of...
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 Proposed AASHTO Guides for Bridge Preservation ActionsDecember 3, 2020 Many transportation departments have significant practical experience with bridge preservation and have developed conclusions regarding the effectiveness of bridge preservation actions based on those experiences. However, limited efforts have been made to identify, measure, evaluate, and document...
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 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge DesignAugust 21, 2020 Performance-based seismic design (PBSD) for infrastructure in the United States is a developing field, with new research, design, and repair technologies; definitions; and methodologies being advanced every year. The TRB National Cooperative Highway Research Program's NCHRP Research Report 949: P...
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 Procedures and Guidelines for Validating Contractor Test DataMay 27, 2020 In the development of a quality assurance program, a state highway agency (SHA) incorporates policies and procedures for assessing how well the materials and construction used by a contractor on a construction project satisfy the agency's specifications. The TRB National Cooperative Highway Resea...
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 Strategies for Work Zone Transportation Management PlansSeptember 18, 2020 One of the ways a state department of transportation or other transportation agency can address work zone safety and other impacts is to develop and implement a transportation management plan (TMP). The TRB National Cooperative Highway Research Program's NCHRP Research Report 945: Strategies for ...
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 Evaluating the Suitability of Roadway Corridors for Use by Monarch ButterfliesJune 1, 2020 Roadsides provide promising monarch habitat as they frequently contain nectar and host plants; however, they also present a range of risks, including pesticide spillover, vehicle collisions, contaminant runoff, and non-native vegetation. The TRB National Cooperative Highway Research Program's NCH...< |