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 emergenc...

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 Nat...

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 High...

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 Doc...

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: Org...

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 AAS...

In states where there is a Transit Risk-Sharing Insurance Pool, state departments of transportation (DOTs) indicate cost reduction and access to insurance as the main objectives of the pools. Among pool benefits, transit agencies find that their insurance premiums were reduced by 15%, they are mostly satisfied with their pool services, and they participate in risk reduction programs. NCHRP Web-...

The efficient movement of freight is the foundation of our communities and economy. Disruptions to the movement of goods can have substantial economic and quality of life effects. At the same time, public sector planners and officials desire a clearer understanding of how goods movement benefits communities through job creation, tax revenues, and other benefits, while balancing the potential en...

Since 2018, state departments of transportation (DOTs) have been required to develop risk-based transportation asset management plans (TAMPs) and to update these plans every four years. However, the absence of maintenance cost data in a TAMP prevents agencies from fully capturing the total investment made to preserve and improve highway infrastructure assets. NCHRP Web-Only Document 372: Incorp...

Technology is at the core of the surface transportation system and is embodied in existing and new scientific knowledge and infrastructure, hardware, and software processes. It is designed to improve performance and cost-effectiveness of infrastructure and the vehicles, systems, and services that utilize the infrastructure. In recent years, a series of rapid advances in key technology areas suc...

Highway agencies use weigh-in-motion (WIM) technology to collect vehicle weight and axle load data on roadways. NCHRP Web-Only Document 370: LTPP Data Analysis: Practical Tools and Procedures to Improve WIM Data Quality , from TRB's National Cooperative Highway Research Program, is a supplemental document to NCHRP Research Report 1070: Tools for Assuring WIM Data Quality: Practical Guide , and ...

The last decade has seen tremendous growth in resources available to state and local transportation agencies for conducting data-driven safety analysis. NCHRP Web-Only Document 369: Estimating Effectiveness of Safety Treatments in the Absence of Crash Data , from TRB's National Cooperative Highway Research Program, describes the process of developing a guide for using alternative, or surrogate,...

The determination of the level-of-service (LOS) at signalized intersections is an important activity for decision-making in the allocation of resources for managing public roads, estimating the impact of new developments, and designing signal timing plans. There is a need to develop models of right-turn-on-red (RTOR) volume to permit users of the Highway Capacity Manual methodology to estimate ...

NCHRP Web-Only Document 367: Postwar Commercial Properties and Section 106: Piloting the Methodology for Evaluating Historic Significance , from TRB's National Cooperative Highway Research Program, provides a guide for practitioners to better understand how to evaluate post-World War II commercial properties for National Register of Historic Places eligibility for transportation projects in co...

To effectively manage the condition and performance of transportation infrastructure, state transportation agencies must assess and manage risks to transportation assets. NCHRP Web-Only Document 366: Risk Assessment Techniques for Transportation Asset Management: Appendices , from TRB's National Cooperative Highway Research Program, presents the risk management resources summarized in NCHRP Res...

Highway infrastructure assets are designed and built to serve long, useful lives. These assets undergo structural aging and degradation driven by traffic and environmental factors, natural and human hazards, and changes in demand and functional use. NCHRP Web-Only Document 365: Implementation of Life-Cycle Planning Analysis in a Transportation AssetManagement Framework , from TRB's National Coo...

As state departments of transportation seek efficiencies to better manage their infrastructure, a boom in wireless and sensing technology options has presented itself. However, the capabilities of the technologies can be misunderstood, which leads to costly implementation efforts that may not leverage the full potential of such technologies. NCHRP Web-Only Document 364: Applications of RFID and...

Cold In-place Recycling (CIR) and Cold Central Plant Recycling (CCPR) are two paving techniques that are experiencing increased use as agencies strive to find cost effective, sustainable solutions to rebuild the national roadway infrastructure without compromising performance. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 363: Construction Guidelines for Cold C...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 4: Great Basin , fro...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 3: Florida , from TR...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 10: Midwest , from TRB...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 15: Southern Plains , ...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 12: Northern Plains , ...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 6: Hawaii , from TRB's...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 16: Southwest , from T...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 5: Great Lakes , from ...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 11: Northeast , from T...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 9: Mid-Atlantic , from...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for the agency and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 2: California , from...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 1: Alaska , from TRB's...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 7: Inland Northwest , ...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 14: Southeast , from T...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 8: Maritime Northwest ...

Transportation agencies can make a difference for imperiled pollinators by managing existing roadside vegetation and designing new revegetation plantings with habitat needs in mind. This can generate public support for agencies and help to mitigate the negative ecological effects of roads. NCHRP Web-Only Document 362: Pollinator Habitat Conservation Along Roadways, Volume 13: Rocky Mountains , ...

There is a need for guidance on how to acquire utility property interests and reimburse utility owners for eligible utility relocation costs. NCHRP Web-Only Document 360: Acquisition of Utility Property Interests and Compensation Practices for Utility Relocations , from TRB's National Cooperative Highway Research Program, develops guidelines that provide a framework for practitioners to follow ...

The co-location of utilities and roadways emphasizes the need for resolute guidelines on accommodating utility and telecommunication facilities in public right-of-way (ROW). Departments of Transportation (DOTs), as often the managers of this ROW, need to understand their rules and options in accommodation and in possible compensation from those accommodations. NCHRP Web-Only Document 359: Valua...

Performance management has become increasingly important for transportation agencies in recent years. A key component of performance management is setting targets, which can be challenging. NCHRP Web-Only Document 358: Developing a Guide to Effective Methods for Setting Transportation Performance Targets , from TRB's National Cooperative Highway Research Program, is supplemental to NCHRP Resear...

There are many strategies and treatments that agencies can consider for implementation to address wrong-way driving maneuvers, ranging from conventional traffic control devices to specialized geometric design elements and various intelligent transportation systems-based solutions. NCHRP Web-Only Document 357: Wrong-Way Driving Solutions, Policy, and Guidelines , from TRB's National Cooperative ...

AASHTO is the author of two documents that have guided utility accommodation highways for decades. The first document primarily applies to utility accommodation on highways that are part of the Federal Aid system. The second document primarily applies to utilities on state highways. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 356: Development of a Guide for A...

Chief executive leadership of transportation agencies have placed substantial emphasis on the protection of IT systems against cyber threats. Less focus has been devoted to the risks to operational technology (OT) and equipment or in protecting transportation business operations. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 355: Cybersecurity Issues and Protec...

Chief executive leadership of transportation agencies have placed substantial emphasis on the protection of IT systems against cyber threats. Less focus has been devoted to the risks to operational technology (OT) and equipment or in protecting transportation business operations. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 355: Cybersecurity Issues and Protec...

Mobile operations can either move continuously along the roadway as during most striping operations, or intermittently as during a pothole patching operation. Mobile operations on two-lane roadways present unique challenges to transportation agencies, not the least of which is the highly variable conditions encountered in the field. The TRB National Cooperative Highway Research Program's NCHRP ...

Most suspension bridges in use today have cables composed of thousands of steel wires and most of these bridges are aging and carry high volumes of traffic. Deterioration of the elements of the suspension system is a problem, replacement of these elements can be expensive and problematic, while failure could be catastrophic. The TRB National Cooperative Highway Research Program's NCHRP Web-Only...

Highway safety practitioners were given a significant new tool in 2010 with the publication of the AASHTO Highway Safety Manual . In the HSM, crash modification factors (CMFs) were provided to estimate the safety effects for a variety of treatments or countermeasures. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 352: Crash Modification Factors in the Highway S...

The first edition of the Highway Safety Manual has provided methods and procedures for estimating total crashes, crashes by type, and crashes by severity at the site level, project level and corridor level. Crash prediction models are critical in the entire safety management system recommended by HSM, including network screening, economic analysis, project prioritization, and safety effectivene...

Long-term vegetation management strategies that decrease the need for routine chemical and mechanical vegetation control can reduce recurring maintenance costs, highway worker exposure to traffic, impacts to the environment and cultural resources, and maintenance-related delays to the traveling public. However, these strategies vary in their effectiveness, longevity, initial construction costs,...

During the COVID-19 pandemic, transportation agencies' most used public-engagement tools were virtual public meetings, social media, dedicated project websites or webpages, email blasts, and electronic surveys. As the pandemic subsides, virtual and hybrid models continue to provide opportunities and challenges. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 349:...

The Highway Safety Manual (HSM) is a tool that helps transportation agencies make data-driven decisions about safety. It includes methods for quantifying safety performance and predicting crash frequencies. The HSM is currently being updated to include macro-level crash prediction models, which can be used to assess safety trends at a regional or national level. NCHRP Web-Only Document 348: Mac...

Roundabout implementation in the United States has increased in the last decade, and practitioners have learned lessons in successfully applying roundabouts in various land use and transportation environments and contexts. Associated with NCHRP Research Report 1043: Guide for Roundabouts , which provides information and guidance on all aspects of roundabouts, the TRB National Cooperative Highwa...

State transportation agencies (STAs) may need to focus their strategic planning and programmatic initiatives over the next two decades to mitigate threats to, and take advantage of, opportunities for system performance and agency effectiveness. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 346: Programmatic Issues of Future System Performance details a unified ...

Transportation agencies must grapple with a broad range of trends and issues that influence and act upon the systems they manage and operate. Issues include climate change, goods movement, changing centers of population and economic activity, and telework, among others. NCHRP Web-Only Document 345: State Transportation Agency Decision-Making for System Performance: Conduct of Research Report , ...

Limited availability of construction-inspector resources for transportation infrastructure is a major challenge and can lead to accepting material or workmanship without sufficient examination, which can result in quality risks, safety concerns, functional failures, and reduced performance life of highway infrastructure. NCHRP Web-Only Document 344: Risk-Based Construction Inspection: Conduct o...

Freeway congestion usually occurs at freeway merge, diverge, and weaving segments that have the potential to develop bottlenecks. To alleviate or mitigate the impacts of congestion at these segments, a number of active management operational strategies have been implemented such as ramp metering, hard shoulder running, managed lanes, and others. The TRB National Cooperative Highway Research Pro...

Trade-offs between uses of roadway cross sections are understood through a variety of lenses, from safety and operations to comfort and mode choice. Estimates of the impacts of cross-section decision-making on outcome measures include environmental, equity, and economy. NCHRP Web-Only Document 342: Roadway Cross-Section Reallocation: Conduct of Research Report , from TRB's National Cooperative ...

NCHRP Web-Only Document 341: Roadside Database Coding Manual , from TRB's National Cooperative Highway Research Program, is supplemental to NCHRP Research Report 1033: Long-Term Roadside Crash Data Collection Program . The document provides a coding manual for the NCHRP Project 17-43 database , a relational database that interfaces with the NASS CDS database, incorporating additional informati...

Dynamic curbside management has been the purview of cities, with much of the relevant research and guidance directed toward local transportation agencies. However, state departments of transportation, metropolitan planning organizations, and other regional agencies can be important partners for these local entities because, in many cases, roadways and other curb zone elements are part of the re...

Access management has many benefits, including, but not limited to, improved safety, reduced delay, better multimodal quality of service, and livability. Yet government agencies often find themselves under intense pressure to yield to requests for more (or poorly located) access connections, or to forego a raised median that will preserve or restore roadway safety. The TRB National Cooperative ...

Implements of husbandry (IoH) are vehicles designed for agricultural purposes and exclusively used in the conduct of agricultural operations. The TRB National Cooperative Highway Research Program's  NCHRP Web-Only Document 338: Quantifying the Effects of Implements of Husbandry on Pavements: Appendices is supplemental to   NCHRP Research Report 1019: Quantifying the Effects of Impleme...

Construction inspectors (CIs) are the frontline workforce that ensures the work on transportation infrastructure projects meets the design and contract requirements and that the finished product meets or exceeds the quality standards. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 337: Training and Certification of Construction Inspectors for Transportation Infr...

Crash data show that more than 18,000 traffic fatalities per year result from roadway departures, and over 7,000 of those roadway departure crashes involved collisions with roadside fixed objects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 336: Proposed Guidelines for Fixed Objects in the Roadside Design Guide helps develop an evaluation methodology and desi...

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 i...

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 334: Roadside Barrier Designs near Bridge Rail Ends with Restricted Rights-of-Way: A National Survey and Testing Reports includes appendices to NCHRP Research Report 1013: Roadside Barrier Designs near Bridge Rail Ends with Restricted Rights-of-Way: A Guide , which describes the application and installation of short...

State departments of transportation (DOTs) face increasingly stringent requirements for stormwater quantity and quality. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 333: Watershed Approach to Mitigating Hydrologic Impacts of Transportation Projects: Conduct of Research Report  describes the development of a watershed-based approach to mitigating hydrolog...

The evolution of roadside hardware in the past has been largely dictated by changes to crash testing guidelines rather than observed field performance. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 332: Multi-State In-Service Performance Evaluations of Roadside Safety Hardware develops a unified format and nationally compatible "in-service performance evaluatio...

Innovative and emerging mobility services offer travelers more options to increase mobility and access goods and services. In addition, various technological developments have the potential to alter the automotive industry and traveler experience, as well as mobility and goods access. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 331: Mobility on Demand and Aut...

With an accessibility perspective, land use changes can bring transportation improvements by bringing activity locations closer together. If incorporated into transportation performance management, accessibility has the potential to highlight projects that would otherwise be overlooked because of their congestion-related impacts. The TRB National Cooperative Highway Research Program's NCHRP Web...

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 329: Bonded Concrete Overlays on Asphalt Pavements: Resources for Evaluation  provides Appendices A through G of the contractor’s final report, which detail survey responses from transportation agencies on bonded concrete overlays on asphalt pavements as well as agency plans and projects. The document is supple...

Across the United States, maximum speed limit laws vary dramatically. In the mid-1990s, many states increased speed limits to 75 mph on select roads. More recently, some states have established speed limits greater than 75 mph. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 328: Safety Effects of Raising Speed Limits to 75 mph and Higher is supplemental to NCHRP...

Motorcycle riders account for more fatalities than the passengers of any other vehicle type involved in a guardrail collision. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 327: Serious and Fatal Motorcycle Crashes into Traffic Barriers: Injury Information is a supplemental document to NCHRP Research Report 1005: Motorcycle Crashes into Traffic Barriers: Factor...

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 E...

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 ...

In June 2014, eight associations that represent government agencies involved in highway safety released the document Toward Zero Deaths: A National Strategy on Highway Safety . This national strategy describes a long-term vision of zero traffic-related deaths and outlines the current challenges that need to be tackled. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Docum...

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 G...

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 technolog...

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 Pro...

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 Highwa...

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 de...

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 Su...

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 t...

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-O...

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 fo...

The use of precast pretensioned girders using 0.7-in. diameter strands would help bridge designers extend the spans of the existing girder shapes. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 315: Details of the Study on the Use of 0.7-in Diameter Strands in Precast Pretensioned Girders is supplemental to NCHRP Research Report 994: Use of 0.7-in. Diameter Stra...

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 2...

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 We...

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 201...

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 Develop...

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 Consistenc...

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...

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 predicti...

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...

Many technical and institutional issues related to estimating and reducing greenhouse gas emissions (GHGs) lie across a wide spectrum of the activities undertaken by state departments of transportation (DOTs). The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 308: Methods for State DOTs to Reduce Greenhouse Gas Emissions from the Transportation Sector documents the...

Since bridges cross over large spans of space they often cross significant features such as busy transportation corridors. In addition, bridges carry heavy vehicles sometimes with dangerous cargos, such as fuel and hazardous chemicals. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 307: Recommended Guidelines for the Selection of Test Levels 2 Through 5 Bridge R...

Prior to this research project, state highway agencies did not have tools for reflecting safety in their decisions concerning freeway and interchange projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 306: Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges documents a safety prediction method for freeways that is suitable for inc...

Porous Friction Course (PFC) mixtures are designed with an open aggregate structure to yield high inplace air voids (i.e., typically between 15 and 20 percent). This allows rainwater to drain horizontally through the layer toward the edge of the pavement structure, thereby improving pavement surface friction. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 305: V...

Guardrails are an important feature of the roadside that are used to shield errant motorists from becoming involved in even more catastrophic crashes by redirecting vehicles away from fixed hazards such as trees and poles and terrain hazards such as steep roadside slopes and fill embankments. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 304: Criteria for Resto...

Understanding and communicating consistently reliable crash prediction results are critical to credible analysis and to overcome barriers for some transportation agencies or professionals utilizing these models. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 303: Understanding and Communicating Reliability of Crash Prediction Models provides guidance on being ab...

The Moving Ahead for Progress in the 21st Century Act (MAP-21) requires a set of performance metrics to include assessment of serious injuries in crashes. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 302: Development of a Comprehensive Approach for Serious Traffic Crash Injury Measurement and Reporting Systems presents a roadmap for states to develop comprehen...

Traffic Incident Management activities have advanced in recent years to become a critical part of transportation operations, as well as a significant budget expenditure. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 301: Development of Guidelines for Quantifying Benefits of Traffic Incident Management Strategies seeks to improve uniformity in measurement, acces...

Hydroplaning is a serious problem that is associated with a relatively small but significant number of crashes. Statistics from various parts of the world indicate that approximately 15% to 20% of all road traffic crashes occur in wet weather conditions. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 300: Guidance to Predict and Mitigate Dynamic Hydroplaning on ...

Several controlled laboratory studies have shown that air voids (AV) can have a large effect on the performance of asphalt pavements. AVs that are either too high or too low can cause a reduction in pavement life. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 299: Investigating the Relationship of As-Constructed Asphalt Pavement Air Voids to Pavement Performanc...

Excessive contract time is costly because it extends a construction crew’s exposure to traffic, prolongs the inconvenience to the public, and subjects motorists to less than desirable safety conditions for longer periods. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 298: Developing a Systematic Approach for Determining Construction Contract Timeseeks to provid...

The first edition of the Highway Safety Manual  (HSM), in 2010, included Safety Performance Functions (SPFs) for roadway segments and intersections. However, not all intersection types are covered in the first edition of the HSM. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 297: Intersection Crash Prediction Methods for the Highway Safety Manual develops ...

Run-off-road traffic crashes account for almost one-third of the deaths and serious injuries each year on U.S. highways. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 296: Guidelines for Cost-Effective Safety Treatments of Roadside Ditches provides new proposed design guidance for the configuration of ditches adjacent to the roadway. A supplemental PowerPoint S...

The release of the Highway Safety Manual (HSM) by the American Association of State Highway and Transportation Officials (AASHTO) in 2010 was a landmark event in the practice of road safety analysis. Before it, the United States had no central repository for information about quantitative road safety analysis methodology. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Do...

A workshop, "Revised Contraction Scour Analysis," is presented in this training manual. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 294: Revised Clear-Water and Live-Bed Contraction Scour Analysis Training Manual adheres to the guidance promulgated by the National Highway Institute and the International Association of Continuing Education and Training for adu...

Over the past 15 years, the nation’s transportation systems have experienced numerous significant disruptions that have resulted in economic loss and loss of human life. The 2020 COVID-19 pandemic is a recent example of how unexpected events can affect the performance and role of transportation systems. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 293: Deployi...

Highway agencies can use a method to assess roadside hardware and establish priorities on how upgrades of hardware should occur for individual projects or establish policy guidelines on roadside hardware assessments. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 292: Roadside Hardware Replacement Analysis: User Guide presents how to implement and plan for asses...

Several types of speed limits exist, including statutory speed limit, posted speed limit, school zone speed limit, work zone speed limit, variable speed limit, and advisory speed. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 291: Development of a Posted Speed Limit Setting Procedure and Tool documents the research efforts and findings from an NCHRP Project 17-...

The procedures detailed in the 6th Edition of the Highway Capacity Manual (HCM) estimate capacity and several operational measures, including those determining Level of Service, for freeway facilities as well as surface streets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 290: Highway Capacity Manual Methodologies for Corridors Involving Freeways and Surface ...

State Departments of Transportation (DOTs) and other government agencies recognize the value of connected vehicle (CV) technologies in helping achieve the strategic objectives of saving lives and relieving congestion. Several agencies are currently planning and preparing for a future where CV technologies could become a part of their routine business operations. A core consideration in any such...

New definitions will help pavement cracking survey providers and pavement engineers at state highway administrations conduct objective cracking measurements and encourage continuing technological innovations by researchers and vendors. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 288: Standard Definitions for Common Types of Pavement Cracking helps develop sta...

Integrated Corridor Management (ICM) is an operational concept that seeks to reduce congestion and improve performance by maximizing the use of available multimodal capacity across a corridor, including highways, arterial roads, and transit systems. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 287: Planning and Implementing Multimodal, Integrated Corridor Mana...

Active Traffic Management (ATM) strategies have become more common in the United States as state departments of transportation grapple with increasing congestion and fewer dollars available to add capacity to keep pace. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 286: Principles and Guidance for Presenting Active Traffic Management Information to Drivers deve...

Highway agencies have traditionally managed the safety improvement process by identifying and correcting high-crash locations (“hot-spots”), where concentrations of crashes and, often, patterns of crashes of similar types, were found. However, when crashes are evaluated over too short a period of time (3 years or less), locations may be identified as hot-spots simply due to the random nature of...

Few resources provide information related to selecting the most appropriate traffic signal phasing for the various geometric and operational situations encountered in the field. This is especially true for left-turn signal phasing decisions with respect to the level of control for the left-turn movement and whether left turns should precede or follow the main through movement. The TRB National ...

Predicting the future of the construction market is always a challenging task - regardless of whether it is over the next one or 20 years - since it involves several uncertainties. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 283: Improving Mid-Term, Intermediate, and Long-Range Cost Forecasting for State Transportation Agencies documents the research that led...

The amount of data surrounding the application of emerging technologies is expanding, producing “big data” at magnitudes not previously seen. While a few agencies have found some success with individual projects, most are uncertain on how to handle this level of big data at an organizational level. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 282: Framework fo...

There is a lot of evidence that Native American tribes could be better involved in planning transportation projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 281: Integrating Tribal Expertise into Processes to Identify, Evaluate, and Record Cultural Resources explores how unique tribal perspectives and expertise could inform the tribal engagement and consu...

There is mounting evidence demonstrating the effectiveness of wildlife overpasses and underpasses in improving motorist safety and conserving wildlife. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 280: Valuing Wildlife Crossings and Enhancements for Mitigation Credits synthesizes current practices used by state DOTs and their partners for calculating and apply...

With a quick online search, you can discover the answers to all kinds of questions. Findability within large volumes of information and data has become almost as important as the answers themselves. Without being able to search various types of media ranging from print reports to video, efforts are duplicated and productivity and effectiveness suffer. The TRB National Cooperative Highway Resear...

Thousands of workhorse bridges — which have spans of less than 300 feet —  are located in historic districts or adjacent to historic structures. These bridges are often considered character-defining features in the landscape and may also serve as important crossings. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 278: Context-Sensitive Design Options for Wo...

There is an emerging view in the construction industry that better performance or better value for money can be achieved by integrating teamwork for planning, design, and construction of projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 277: Implementing Alternative Technical Concepts in All Types of Highway Project Delivery Methods seeks to assist integr...

Transportation management plans (TMPs) are a set of coordinated strategies designed to help agencies achieve work zone project goals related to traffic mobility, efficient system operation, motorist and worker safety, and other operational targets. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 276: Evaluating Strategies for Work Zone Transportation Management P...

Section 106 of the National Historic Preservation Act (NHPA) requires transportation agencies to consider the effects of their undertakings on historic resources when those undertakings are federally funded. Section 106 of the NHPA also allows for the use of Program Alternatives to tailor compliance, potentially streamlining Section 106 evaluations for commonly encountered categories of histori...

Vehicle electrification is one of the emerging and potentially disruptive technologies that are being considered to reduce emissions of criteria pollutants, mobile source air toxics (MSATs), and greenhouse gases (GHGs) from motor vehicles. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 274: Zero Emission Vehicles: Forecasting Fleet Scenarios and their Emissions ...

Prior to 2013, the use of bicycle-specific signals in the U.S. was limited to a few jurisdictions. However, in recent years, the number of installations has grown rapidly. This research identified more than 500 intersections using bicycle signals in a variety of contexts. Despite the recent approval and practice, the TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 27...

The National Cooperative Highway Research Program's NCHRP Web-Only Document 272: Existing and Emerging Highway Infrastructure Preservation, Maintenance, and Renewal Definitions, Practices, and Scenarios provides appendices to NCHRP Report 750, Volume 7: Preservation, Maintenance, and Renewal of Highway Infrastructure .

Cost-benefit analysis (CBA) is useful for climate change response and adaptation, and if used properly, it has great potential for long-range planning. CBA should help agencies navigate the spectrum of decisions from mitigation and greenhouse gas reduction to adaptation: where does investing public funds generate the most public good? The TRB National Cooperative Highway Research Program's NCHR...

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 270: Developing a Guide to Ensuring Access to the Publications and Data of Federally Funded Transportation Research  provides guidance for state departments of transportation (DOTs) to help them meet the requirements of the U.S. DOT Public Access Plan requiring preservation of the products of all federally fund...

The majority of instances of explicit consideration of service life design has been limited to signature bridges and other projects where extended service lives (in other words, greater than 100 years) are specified by the owner. Many state departments of transportation and other transportation agencies have recognized the importance of implementing service life design for typical highway bridg...

Transportation plays a critical role in emergency management. After all, state transportation agencies have large and distributed workforces, easy access to heavy equipment, and a robust communications infrastructure capable of sustained mobilization. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 267: Developing a Guide to Emergency Management at State Transpor...

Small events pose threats of great consequences since the impact of any incident is magnified when a transportation network is operating at or past its capacity—as is the case in portions of many states as travel demand on their transportation networks grows. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 266: Developing a Physical and Cyber Security Primer for ...

There are several best management practices that are good at removing particulate-bound pollutants by settling, filtering, and, in the case of wetlands, settling, uptake, and incorporation of pollutants into biological matter (e.g., natural organic matter). However, a longstanding goal of stormwater treatment is the removal of the stormwater pollutant fraction that cannot be readily settled or ...

The performance of flexible and rigid pavements is known to be closely related to properties of the base, subbase, and/or subgrade. However, some recent research studies indicate that the performance predicted by this methodology shows a low sensitivity to the properties of underlying layers and does not always reflect the extent of the anticipated effect, so the procedures contained in the Ame...

While not all right-sizing projects involve a change in jurisdictional responsibility and ownership, jurisdictional transfer can be a key tool for implementing right-sizing plans and agreements. As a supplemental document to NCHRP Research Report 917: Right-Sizing Transportation Investments:A Guidebook for Planning and Programming , the TRB National Cooperative Highway Research Program's NCHRP ...

A programmatic approach to sustainable materials procurement in highway construction may be better than one-off attempts. For now, there is little guidance on procuring sustainability in highway construction and sustainability is not as important as cost or schedule. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 262: Sustainable Highway Construction describes t...

NCHRP Web-Only Document 261: Case Studies of Truck Activity Data for Emissions Modeling consists of seven case studies that are appendices A to G of NCHRP Report 909: Guide to Truck Activity Data for Emissions Modeling. NCHRP Research Report 909 explores methods, procedures, and data sets needed to capture commercial vehicle activity, vehicle characteristics, and operations to assist in estimat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 260: Proposed Refinements to Design Procedures for Geosynthetic Reinforced Soil (GRS) Structures in AASHTO LRFD Bridge Design Specifications explores the effect of adopting a closely‐spaced reinforcement layout in geosynthetic‐reinforced soil structures. While research since the early 1980s has identified the benefici...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 259: Guidelines to Improve the Quality of Element-Level Bridge Inspection Data is intended to assist inspectors in identifying defects and assigning the appropriate condition state for bridge elements. To ensure the safety and serviceability of bridges, the guidelines include accuracy requirements designed to help pro...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 258: Manual on Subsurface Investigations provides an update to the American Association of State Highway Transportation Officials (AASHTO) 1988 manual of the same name. This report reflects the changes in the approaches and methods used for geotechnical site characterization that the geotechnical community has develop...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 257: A Mechanistic–Empirical Model for Top–Down Cracking of Asphalt Pavements Layers develops a calibrated mechanistic-empirical (ME) model for predicting the load-related top-down cracking in the asphalt layer of flexible pavements. Recent studies have determined that some load-related fatigue cracks in asphalt pavem...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 256: Assessing Interactions Between Access Management Treatments and Multimodal Users describes operational and safety relationships between access management techniques and the automobile, pedestrian, bicycle, public transit, and truck modes. This contractor's report may help assist in the selection of alternati...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 255: Improved Analysis of Two-Lane Highway Capacity and Operational Performance supplements the sixth edition of the Highway Capacity Manual (HCM). Specifically, this project includes the following updates: the development of a more realistic speed-flow relationship the introduction of a new service measure—follower d...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 254: Underwater Installation of Filter Systems for Scour and Erosion Countermeasures, Volume 2: Training Manual provides training on the underwater placement of filters, and can be adapted into a workshop or distance learning presentations. The project provides guidance on design procedures, material testing requireme...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 254: Underwater Installation of Filter Systems for Scour and Erosion Countermeasures, Volume 1: Research Report documents the research effort of NCHRP Research Report 887 : Guidance for Underwater Installation of Filter Systems. The project provides guidance on design procedures, material testing requirements, install...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 6: Implementation Plan provides a technical memorandum on how to put the research findings and products into practice; identifies possible institutions that might take leadership in applying the research findings/products; and identifies issues affecti...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 5: Developing the Autonomous Vehicle Action Plan provides technical background on developing Volumes 1 through 4 of NCHRP Web-Only Document 253. It includes further background on terminology and definitions used in the suite of reports; legal and regul...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 4: Autonomous Vehicle Action Plan (AVAP) develops awareness of the legislative landscape and the foundational laws and regulations that may need to be prioritized for modification for Connected and Automated Driving Systems (C/ADSs) technologies. The A...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 3: Legal Modification Prioritization and Harmonization Analysis identifies how and when regulations and laws will need to be modified to facilitate the implementation of Connected and Automated Driving Systems (C/ADSs)-equipped vehicles. The report als...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 2: State Legal and Regulatory Audit assists state agencies as they work to adapt their legal programs to reflect the realities of Connected and Automated Driving Systems (C/ADSs)—a term that in this report encompasses both vehicle connectivity and an A...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 253: Implications of Connected and Automated Driving Systems, Vol. 1: Legal Landscape explores federal, state, and international legal activities and practices regarding Connected and Automated Vehicles and Highly Automated Vehicles (C/AV/HAVs): Section 1 reviews United States federal activities within the sphere of r...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 252: A Strategic Approach to Transforming Traffic Safety Culture to Reduce Deaths and Injuries provides guidance on developing a strategic approach to transform the traffic safety culture of road users and stakeholders. The goal is to use this approach to sustain improvements in traffic safety for all road users, incl...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 251: Spot Painting to Extend Highway Bridge Coating Life: Volume 2: Research Overview documents the evaluation method for a guidance document that provides approaches for employing spot painting in a cost-effective, safe, and environmentally compliant manner. Bridge coatings are the primary means of corrosion pro...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 251: Spot Painting to Extend Highway Bridge Coating Life: Volume 1: Guidance provides approaches for employing spot painting in a cost-effective, safe, and environmentally compliant manner. Bridge coatings are the primary means of corrosion protection for steel bridges in the United States. Most bridge coatings tend t...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 250: Use of Automated Machine Guidance within the Transportation Industry studies automated machine guidance (AMG) implementation barriers and develop strategies for effective implementation of AMG technology in construction operations. AMG links design software with construction equipment to direct the operations of ...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 249: Combining Individual Scour Components to Determine Total Scour explores the relationships among individual scour components observed in the same flow event at a bridge. The report provides insight into ways to combine scour components to produce realistic estimates of total scour depth for safe and economical des...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 248: Research on Creating and Sustaining a Culture of Innovation for Departments of Transportation documents the research process and provides key guidance to implement the research produced in NCHRP Research Report 885 : Guide to Creating and Sustaining a Culture of Innovation for Departments of Transportation. This ...

TRB's National Cooperative Highway Research Program (NCHRP)  Web-Only Document 247: Managing Geotechnical Risks in Design–Build Projects documents the research effort to produce NCHRP Research Report 884 : Guidelines for Managing Geotechnical Risks in Design–Build Projects. NCHRP Research Report 884 provides guidelines for the implementation of geotechnical risk management measures for des...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 246: Volume 2: TRAQS: A Combined Interface for Project-Level Air Quality Analysis documents the development of TRAQS (TRansportation Air Quality System), a Graphical User Interface-based software application that simplifies project-level air quality analysis of mobile source emissions. TRAQS integrates the “modeling c...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 246: Volume 1: TRAQS User Guide provides guidance for using the TRansportation Air Quality System (TRAQS). TRAQS is an open source software designed to conduct mobile air quality assessments for three primary purposes: Project-Level Conformity (Hot-Spot Analyses) National Environmental Policy Act (NEPA) General Transp...

TRB's National Highway Cooperative Research Program (NCHRP) Web-Only Document 245: Bridge Superstructure Tolerance to Total and Differential Foundation Movements develops an understanding of the levels of support movements that bridges may tolerate before exceeding strength or service limit states. This research explores analytical procedures to objectively determine the acceptable levels of br...

The aging U.S. highway system, coupled with fiscal constraints, is placing increased pressures on highway agencies to maintain the highway system in a cost-effective manner and is, thus, creating greater needs for 3R projects. The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 244: Developing Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing,...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 243: Recommended Guidelines for Prefabricated Bridge Elements and Systems Tolerances and Recommended Guidelines for Dynamic Effects for Bridge Systems documents the results of two studies that have produced guidelines to the American Association of State Highway and Transportation Officials (AASHTO) for adop...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 242: Recommended AASHTO Guide Specifications for ABC Design and Construction documents the results of a synthesis of past research regarding Accelerated Bridge Construction (ABC), leading to the development of Guide Specifications for Accelerated Bridge Construction. Part 1 of the report includes Design Specifications...

TRB's National Cooperative Highway Research Program (NCHRP) Web Only Document 241: Development and Management of Sustainable Enterprise Information Portals documents the research approach and methodology to develop  NCHRP Research Report 865 : Guidance for Development and Management of Sustainable Enterprise Information Portals. The guidance addresses the  development and managem...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 239: Impacts of Laws and Regulations on CV and AV Technology Introduction in Transit Operations explores the potential barriers imposed by operating policies, agency regulations, and governmental laws relative to the transit environment. Without adjustment, the combination of new technology with old rules could result...

TRB's National Cooperative Highway Research Program (NCHRP)  Web-Only Document 238: Developing the Guide to Retaining Essential Consultant-Developed Knowledge Within DOTs documents the methodology used to develop NCHRP Research Report 867 :  Keeping What You Paid For—Retaining Essential Consultant-Developed Knowledge Within DOTs . The document also provides key findings of the project...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 237: Environmental Justice Analyses When Considering Toll Implementation or Rate Changes—Final Report presents information gathered in the development of NCHRP Research Report 860 : Assessing the Environmental Justice Effects of Toll Implementation or Rate Changes: Guidebook and Toolbox. This web-only document summari...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 236: Incorporating Slab/Underlying Layer Interaction into the Concrete Pavement Analysis Procedures develops mechanistic-empirical (M-E)  models (and software) to consider the interaction between the concrete slab and base layer and its effect on pavement performance. The current American Association of State Hig...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 235: Quantifying the Influence of Geosynthetics on Pavement Performance develops a methodology for quantifying the influence of geosynthetics on pavement performance for use in pavement design and analysis. This project focused on the use of geosynthetics in unbound base/subbase layers or as a base/subgrade interface ...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 234: Developing a Method Selection Tool for Travel Forecasting documents research undertaken to provide guidance on travel forecasting methods to agencies with diverse planning needs. This project sought to produce applicable methods by evaluating agencies’ planning programs, desired performance metrics, requirements,...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 233: Mainstreaming Transportation Hazards and Security Risk Management: CAPTA Update and Implementation provides an update and enhancement of the CAPTA methodology and CAPTool for realistic costing . The suite of materials produced include a quick start guide to use the CAPTool, as well as a dataset populated with exa...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 232: Communications Worker Credentialing Requirements focuses on credentialing requirements needed for communications workers to physically access disaster-impacted areas to restore damaged wireline telecommunication networks. Under the advice of a Federal Communications Commission (FCC) panel that reviewed the impact...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 231: Challenges to CV and AV Applications in Truck Freight Operations explores connected vehicle (CV) and automated vehicle (AV) technology, focusing on heavy trucking. The report identifies existing and emerging freight regulatory, planning, policy, and operational environments and challenges for connected and autono...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 230: Developing an Expanded Functional Classification System for More Flexibility in Geometric Design, which documents the methodology of NCHRP  Research Report 855 : An Expanded Functional Classification System for Highways and Streets builds upon preliminary engineering of a design project, including developing...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 229: Methods and Technologies for Pedestrian and Bicycle Volume Data Collection: Phase 2 explores automated count technologies that capture pedestrian and bicycle volume data. The publication focuses on technologies that came onto the market too late to be included in previous Phase 1 research. Findings from Phase 1 a...

TRB's National Cooperative Highway Research Program ( NCHRP) Web-Only Document 228 : Safety Impacts of Intersection Sight Distance documents the methodology and presents the results from NCHRP Research Report 875 : Guidance for Evaluating the Safety Impacts of Intersection Sight Distance. It provides  the underlying research on estimating the safety effects of intersection sight distance (...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 227: Design of Interchange Loop Ramps and Pavement/Shoulder Cross-Slope Breaks is presented in two parts. Part 1 presents design guidance for interchange loop ramps based on observational field studies and safety analyses and includes suggestions for the next edition of A Policy on Geometric Design of Highways and Str...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 226: Data Visualization Methods for Transportation Agencies provides techniques for planners who have various levels of experience with displaying and reporting information in a visual format. The publication includes practices for developing visualization skills, enhancing transportation analysis, and improving publi...