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 in T...

A major use of Mechanically Stabilized Earth (MSE) walls is as bridge approach embankments, where they are typically constructed with a roadside barrier system supported on the edge of the walls. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 326: Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Eart...

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 of ...

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 Guid...

Work zone intrusion technologies are available that provide an opportunity to prevent and mitigate vehicle intrusions into roadway work zones. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 322: Alternative Technologies for Mitigating the Risk of Injuries and Deaths in Work Zones: Conduct of Research provides a comprehensive synthesis and evaluation of technologies...

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 Progra...

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 Highway R...

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 detai...

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 Subur...

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 to i...

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-Only...

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 for R...

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 2000...

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 Web-O...

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 2018 G...

Despite widespread use of walking as a transportation mode, walking has received far less attention than the motor vehicle mode in terms of national guidance and methods to support planning, designing, and operating safe, functional, and comfortable facilities. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 312: Enhancing Pedestrian Volume Estimation and Developing...

Project-level Programmatic Agreements (PAs) streamline and expedite the environmental review process and provide departments of transportation with greater flexibility in decision making regarding adverse effects to historic properties and defining appropriate mitigation. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 311: Improving the Efficiency and Consistency o...

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 as...

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 prediction ...

Left or right shoulders can be strategically opened as travel lanes, and "part-time shoulder use" is defined as using a shoulder "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 1: Informational Guide and Safety Evaluation Guidelines provides an overview of pa...