The transportation field is undergoing a transformative change in response to several technological innovations resulting in the emergence and widespread adoption of new mobility options (NMOs) such as shared micromobility, transportation networking companies (TNCs), and connected and autonomous vehicles (CAVs). NCHRP Web-Only Document 399: Developing a Guide for New Mobility Options in Travel Dem...

Traffic Incident Management (TIM) is the process to detect, respond to, and clear traffic incidents so that traffic flow may be restored as safely and quickly as possible. Traffic incidents are unplanned events, such as crashes, that impact traffic flow, and TIM refers to the coordinated process to respond to and clear the incidents. NCHRP Web-Only Document 395: Impacts of Connected, Automated Veh...

When a separate lane is provided for left-turning vehicles, the interval during which drivers turn can be described as either protected or permissive. In a protected left-turn movement, the left-turning driver has the exclusive right-of-way and faces no other (legal) conflicts. In a permissive left-turn movement, the left-turning driver may turn only after yielding to other conflicting movements, ...

Heavy vehicle traffic and vehicle mix have a substantial impact on crash frequency and severity. The consideration of vehicle mix would improve predictive methods for crash frequency and severity. Improved methods will result in better use of the limited funds and resources available for improving the safety of the highway system and supporting performance-based approaches. NCHRP Web-Only Document...

Extreme events, such as hurricanes, tornados, floods, earthquakes, fires, and collisions, pose a threat to the transportation infrastructure that millions of people depend on daily.  NCHRP Web-Only Document 390: Response Planning, Assessment, and Rapid Restoration of Service of Bridges in Extreme Events: Background and Summary , from TRB's National Cooperative Highway Research Program, supple...

Cracking and durability issues of asphalt pavements have been primary concerns of departments of transportation the last two decades. Several modes of asphalt pavement cracking exist—fatigue, top-down, reflective, and thermal—and all are influenced by thermal loading, traffic loading, or a combination of both. NCHRP Web-Only Document 389: Ruggedness of Laboratory Tests to Assess Cracking Resistanc...

Since the inception of using sets of plans for construction purposes, a persistent challenge has been the miscommunication between designers and constructors, even when they were part of the same organization. NCHRP Web-Only Document 388: Framework for Implementing Constructability Throughout Project Development from NEPA to Final Design , from TRB's National Cooperative Highway Research Program, ...

In an effort to relieve highway congestion and promote the movement of people, some state departments of transportation have modified their freeway facilities to include high occupancy vehicle lanes, high occupancy toll lanes (HOT, or HO lanes), and other managed lane strategies. NCHRP Web-Only Document 387: Safety Prediction Model for Freeway Facilities with High Occupancy Lanes , from TRB's Nati...

Transportation corridors are defined by the infrastructure, services, and relationships connecting places. A corridor can be a national resource connecting large cities, a regional passage connecting a state’s trade centers, or local pathways connecting through a city or town. NCHRP Web-Only Document 386: Quantifying the Impacts of Corridor Management , from TRB's National Cooperative Highway Rese...

As transportation agencies face an increasing frequency and magnitude of risks, strategies and tools are essential for demonstrating, communicating, and gaining support for integrating resilience into transportation decisions and investments. NCHRP Web Only Document 385: Business Case and Communications Strategies for State DOT Resilience Efforts , from TRB's National Cooperative Highway Research ...

Transportation plays a crucial role before, during and after an emergency. Transportation agencies’ unique role stems from their broad range of capabilities and responsibilities.   NCHRP Web-Only Document 384: Developing an Emergency Management Playbook for State Transportation Agencies , from TRB’s National Cooperative Highway Research Program, helps develop a playbook to support emergency m...

There are many seismic site response analysis programs that operate in either the time domain or the frequency domain. These programs are available as public domain software, as commercial products, and/or through direct contact with the authors. NCHRP Web-Only Document 383: Seismic Site Response Analysis with Pore Water Pressure Generation: Resources for Evaluation , from TRB's National Cooperati...

Traffic safety culture is a complex topic spanning a range of sociological and philosophical concepts as they relate to transportation safety and the systemic framework that produces different kinds of traffic safety-related outcomes. NCHRP Web-Only Document 382: Traffic Safety Culture: Conduct of Research Report , from TRB's National Cooperative Highway Research Program, contributes to the body o...

Most asphalt pavement design methodologies assume pavements as monolithic structures composed of multiple layers to transfer the traffic loads on the surface to the bottom layers. However, this assumption is compromised when the pavement layers are not fully bonded. NCHRP Web-Only Document 381: Developing Laboratory Methods and Specification Language to Test Tack Coat Materials , from TRB's Nation...

Recreational travel is a major and growing activity in the United States. Recreation trips to outdoor parklands tend to have different characteristics than trips for other types of recreation, such as entertainment, sporting events, and regular exercise. NCHRP Web-Only Document 380: Accessing America's Great Outdoors: Forecasting Recreational Travel Demand , from TRB's National Cooperative Highway...

System-disrupting events, including those stemming from integrated cyber and physical components, intentional criminal acts, a global pandemic, accidents or unintentional human intervention, and natural causes, have only become more sophisticated since NCHRP Research Report 930: Update of Security 101: A Physical Security and Cybersecurity Primer for Transportation Agencies . NCHRP Web-Only Docume...

Large-scale emergencies and disasters (weather-related and other) may be somewhat rare but are not as rare as they used to be, and are generally increasing in intensity and frequency. How state departments of transportation (DOTs) train and coordinate prior to emergencies makes a big difference in how effectively they respond to an emergency. NCHRP Web-Only Document 378: Emergency Response: Organi...

A variety of intersection control evaluation processes and metrics are used by highway agencies for evaluating intersection geometry and control options and identifying an optimal geometric and control solution for an intersection. These processes usually address safety, operational, multimodal, environmental, right-of-way, and cost impacts and other considerations. NCHRP Web-Only Document 377: Ba...

NCHRP Web-Only Document 376: Rapid Tests and Specification Language for Construction of Asphalt-Treated Cold Recycled Pavements , from TRB's National Cooperative Highway Research Program, provides the results and analysis of field testing conducted to verify the short-pin raveling test (SPRT) and long-pin shear test (LPST) threshold values recommended in NCHRP Research Report 960: Proposed AASHTO ...

Good quality pavement construction translates directly to good performance and long life. State departments of transportations (DOTs) apply established standards and specifications to perform a wide range of material tests through various stages of a construction contract in accordance with federal aid requirements and state DOT specific requirements. NCHRP Web-Only Document 375: Incorporating Non...