Travel time reliability is frequently cited as an important metric for the trucking community and users of truck freight services. While the travel time reliability for trucking is commonly measured, truck reliability is seldom considered in the benefit–cost evaluation of mobility projects, which underrepresents the benefits accrued to freight users of the roadway system. The TRB National Cooperative Highway Research Program's NCHRP Research Report 925: Estimating the Value of Truck Travel Time Reliabili...

Analysis of the erodibility of geomaterials is important for the study of problems related to soil erosion such as bridge scour, embankment overtopping erosion, and stream stability. Erodibility is the relationship between the soil erosion rate and fluid velocity or hydraulic shear stress. Since different soils have different geotechnical properties, their erosion rates vary. The TRB National Cooperative Highway Research Program's  NCHRP Research Report 915: Relationship Between Erodibility and Prop...

Accurate traffic forecasts for highway planning and design help ensure that public dollars are spent wisely. Forecasts inform discussions about whether, when, how, and where to invest public resources to manage traffic flow, widen and remodel existing facilities, and where to locate, align, and how to size new ones. The TRB National Cooperative Highway Research Program's NCHRP Report 934: Traffic Forecasting Accuracy Assessment Research seeks to develop a process and methods by which to analyze and impro...

Recent federal legislation has established requirements for agencies to set performance targets and report on safety, pavement, and bridge conditions; transit asset state of good repair; system performance; freight; and mobile source emissions. These requirements have resulted in increased visibility and attention to Transportation Performance Management (TPM) and increased awareness of the importance of data within that process. The TRB National Cooperative Highway Research Program's NCHRP Report 920:&n...

Laboratory conditioning of asphalt mixtures during the mix design process to simulate their short-term aging influences the selection of the optimum asphalt content. In addition, long-term conditioning affects the mixture and binder stiffness, deformation, and strength evaluated with fundamental characterization tests to assess mixture performance. The current standard conditioning procedure, AASHTO R 30, Standard Practice for Mixture Conditioning of Hot-Mix Asphalt, was developed over two decades ago. I...

State DOTs are increasingly subject to Total Maximum Daily Load (TMDL) requirements for water quality improvement that are implemented through National Pollutant Discharge Elimination System (NPDES) permits. As a result, state DOTs may incur significant costs to construct, operate, maintain, and monitor performance of best management practices and other stormwater treatment facilities that treat stormwater from sources outside the right-of-way, as well as stormwater from roadway sources. TRB’s National C...

"Big data" is not new, but applications in the field of transportation are more recent, having occurred within the past few years, and include applications in the areas of planning, parking, trucking, public transportation, operations, ITS, and other more niche areas. A significant gap exists between the current state of the practice in big data analytics (such as image recognition and graph analytics) and the state of DOT applications of data for traffic incident management ( TIM) (such as the manual u...

Between 2005 and 2011, the number of traffic fatalities in the U.S. declined by 11,031, from 43,510 in 2005 to 32,479 in 2011. This decline amounted to a reduction in traffic-related deaths of 25.4 percent, by far the greatest decline over a comparable period in the last 30 years. Historically, significant drops in traffic fatalities over a short period of time have coincided with economic recessions. Longer recessions have coincided with deeper declines in the number of traffic fatalities. This report f...

More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS). According to the National Asphalt Pavement Association, cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The use of RAP in HMA dates back...

Carbon fiber reinforced polymer (CFRP) is becoming a recognized alternative to traditional construction materials in a wide range of civil engineering applications. An example of such applications is the use of CFRP cables or bars as prestressing tendons for concrete bridge girders, especially in aggressive environments where steel prestressing strands are susceptible to corrosion. Despite their promise, CFRP prestressing tendons have not frequently been used for bridge construction in the United States;...