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;...

Examples of transformational technologies—many are discussed in technical and popular media—include wireless telecommunications, shared vehicles, connected vehicles, fully autonomous vehicles, alternative-fuel vehicles, smart cities and communities, big data analytics, internet-of-things, as well as UAVs or drones, 3-D printing, and more. Public agencies face significant challenges continuing to perform their governmental functions in the face of the private sector’s prodigious output of these new techno...

Pavement smoothness (or roughness) is used by state highway agencies for monitoring network condition and other purposes such as assessing construction quality and optimizing investments in preservation, rehabilitation, and reconstruction. States are also required to report the International Roughness Index (IRI) as an element of the federal Highway Performance Monitoring System (HPMS). Because IRI is not measured directly but is calculated as the mechanical response of a generic quarter-car, traveling a...

State transportation agencies will always fulfill a role in the emergency-management effort - for all incidents, from the routine traffic incident through major emergencies to catastrophic events. State agency plans and procedures are expected (indeed required if the agency seeks federal compensation) to be related to state and regional emergency structures and plans. This involves multi-agency, multi‐jurisdictional cooperation in emergency planning and operations. This pre-publication draft,  NCHRP...

Since 2009, when NCHRP's last Security 101 report was released, there have been significant advances in transportation security approaches, including new strategies, programs, and ways of doing business that have increased the security of transportation systems as well as ensured their resiliency. Hazards and threats to the system have also continued to evolve since 2009. While the incidence of large-scale terrorist attacks has remained small, transportation agencies are at increasingly greater risk...

Firms that have graduated from the federal Disadvantaged Business Enterprise (DBE) program or have successfully competed for state transportation agency contracts are the focus in NCHRP Research Report 913: Compendium of Successful Practices, Strategies, and Resources in the U.S. DOT Disadvantaged Business Enterprise Program. The DBE program provides small businesses owned and controlled by socially and economically disadvantaged persons with opportunities to participate on federally assisted highway con...

Geometric design practitioners in state transportation agencies have a new set of guidelines on probability of vehicle rollover based on various roadside design features. NCHRP Research Report 911: Guidelines for Traversability of Roadside Slopes will assist practitioners in the reduction of serious injury crashes associated with rollovers on roadside slopes. Data from the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS) shows that one-third of single-vehicle run-off-road (SVR...

The distance between the driver’s line of sight along the roadway ahead on a horizontal curve and a sight obstruction on the inside of the curve is known as the horizontal sightline offset (HSO). Highway agencies can use  NCHRP Research Report 910: Design Guidelines for Horizontal Sightline Offsets as guidance to address the types of sight distance restrictions that are most likely to be encountered on specific roadway types.  The relationship between stopping sight distance (SSD) and the frequ...