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...

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:...

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 ...

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...

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...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 224: Research Supporting the Development of Guidelines for Implementing Managed Lanes documents the contractor's final report used to develop NCHRP Report 835 : Guidelines for Implementing Managed Lanes. The report includes detailed background material, gap analysis, design elements, safety performance parameters, and...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 223: Guidelines for Development of Smart Apps for Assessing, Coding, and Marking Highway Structures in Emergency Situations provides guidance for developing mobile devices-based smart applications for preliminary damage assessment responders to use in emergency scenes for assessing, coding, and marking transportation ...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 222: Guidelines for the Application of Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities provides guidance to engineers and planners on the design of roundabouts and channelized turn lanes for accessibility. NCHRP Web-Only Document 222 is the final report for NCHRP R...

TRB's Protection of Transportation Infrastructure from Cyber Attacks: A Primer provides transportation organizations with reference materials concerning cybersecurity concepts, guidelines, definitions, and standards. The primer is a joint product of two TRB Cooperative Research Programs, and is categorized as Transit Cooperative Research Program (TCRP) Web-Only Document 67 and National Cooperat...

TRB’s National Cooperative Highway Research Program (NCHRP ) Web-Only Document 220: Estimating the Life-Cycle Cost of Intersection Designs describes the Life-Cycle Cost Estimation Tool (LCCET). The LCCET spreadsheet allows users to compare alternative intersection designs based on initial construction costs, ongoing maintenance and operations costs, operational efficiencies for a variety of mod...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 219: Hamburg Wheel-Track Test Equipment Requirements and Improvements to AASHTO T 324 evaluates the capability of the Hamburg Wheel Tracking (HWT) devices available in the United States market and identifies potential issues with different aspects of American Association of State Highway and Transportation Officials (...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 218: Field Evaluation of Reflected Noise from a Single Noise Barrier—Phase 1 studies the change in sound levels and characteristics caused by sound reflections off a reflective, non-absorptive noise barrier on the opposite side of a highway.

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 217: Precision and Bias Statements for AASHTO Standard Methods of Test TP 98 and TP 99 documents and presents results of a study of precision and bias associated with two AASHTO standards used to measure tire-pavement noise. The research team digitally recorded audio and video of traffic on segments of highways that w...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 216: Emergency Exit Signs and Marking Systems for Highway Tunnels focuses on determining effective messages for encouraging drivers to leave their vehicles and evacuate a tunnel on foot; determining sign and marking formats that most effectively lead people to emergency tunnel exits; and determining the most visible s...

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 215: Incident Command System (ICS) Training for Field-Level Supervisors and Staff provides training materials and guidance for transportation field personnel to help their organizations operate safely in an emergency or traffic management event. This course is intended to review the basic ICS structures and terminolog...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 214: Transportation Agency Self-Assessment of Data to Support Business Needs: Final Research Report describes the research and methods used to develop NCHRP Report 814 : Data to Support Transportation Agency Business Needs: A Self-Assessment Guide. The guide provides methods to evaluate and improve the value of t...

TRB’s National Cooperative Highway Research Program (NCHRP) Web Only Document 213: Potential MUTCD Criteria for Selecting the Type of Control for Unsignalized Intersections explores the development of criteria and supporting material for determining appropriate traffic control at unsignalized intersections.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 212: Alternative Quality Management Systems for Highway Construction documents the research process, data collection and analysis used to develop NCHRP Report 808: Guidebook on Alternative Quality Management Systems for Highway Construction .

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 211: Close To Home: A Handbook for Transportation-Efficient Growth in Small Communities and Rural Areas provides a vocabulary of land use characteristics in small communities and rural areas. It also estimates the per person change in daily driving after hypothetical growth occurs according to different development vi...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 210: Input Guidelines for Motor Vehicle Emissions Simulator Model, Volume 3: Final Report documents the research process for developing the Practitioners’ Handbooks and tools, and provides additional documentation not included in the handbook. NCHRP Web-Only Document 210 Volume 1: Practitioners’ Handbook: Regional Lev...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 210: Input Guidelines for Motor Vehicle Emissions Simulator Model, Volume 1: Practitioners’ Handbook: Regional Level Inputs provides users of the Motor Vehicle Emissions Simulator Model (MOVES) with tools to help estimate emissions from highway vehicles. Specifically, this handbook provides resource material on develo...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 210: Input Guidelines for Motor Vehicle Emissions Simulator Model, Volume 2: Practitioners’ Handbook: Project Level Inputs provides users of the Motor Vehicle Emissions Simulator (MOVES)  model with tools to help estimate emissions from highway vehicles. Specifically, this handbook provides resource material on d...

TRB’s National Cooperative Highway Research Program (NCHRP) Web Only Document 209: Volume Reduction of Highway Runoff in Urban Areas: Final Report and NCHRP Report 802 Appendices C through F summarizes the research and resulting guidance developed for NCHRP Report 802 : Volume Reduction of Highway Runoff in Urban Areas: Guidance Manual. The document includes a literature review, synthesis, and ...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 208: Design Guidance for Channelized Right-Turn Lanes develops guidance for channelized right-turn lanes based on balancing the needs of motor vehicles, pedestrians, and bicycles.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 207: Evaluation of the Flashing Yellow Arrow (FYA) Permissive Left-Turn in Shared Yellow Signal Sections analyzes driver behavior and comprehension related to the FYA permissive left-turn indication when added to three- and five-section traffic signal displays.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 206: Managing Catastrophic Transportation Emergencies: A Guide for Transportation Executives provides guidance to new chief executive officers (CEOs) about the roles and actions that CEOs take during emergency events.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 205: Methods and Technologies for Pedestrian and Bicycle Volume Data Collection, documents the research that led to the guidance of NCHRP Report 797: Guidebook on Pedestrian and Bicycle Volume Data Collection . Research included the testing and evaluation of a range of automated count technologies that captu...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 204: Crash Experience Warrant for Traffic Signals develops a procedure for evaluating and quantifying the safety of stop-controlled and signal-controlled intersections. The findings from this evaluation were used to develop a proposed crash experience warrant. The main products of the research are the proposed crash e...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 203: Curriculum for New State DOT Transit Grant Managers in Administering Federal and State Transit Grants establishes a curriculum to provide state transit directors with a comprehensive resource to train new staff in Federal Transit Administration program management and subrecipient oversight.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 202: Operation of Traffic Signal Systems in Oversaturated Conditions, Volume 1 – Practitioner Guidance presents an approach for identifying traffic control strategies for mitigating oversaturated conditions at signalized intersections. Specifically, the guidance assists in the process of matching mitigation strategies...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 202: Operation of Traffic Signal Systems in Oversaturated Conditions, Volume 2 – Final Report documents the procedures and methodology used to develop quantitative metrics for oversaturated traffic conditions, identify operational objectives based on observed conditions, develop a methodology for generating timing pla...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 201: Calibration of AASHTO LRFD Concrete Bridge Design Specifications for Serviceability explores calibrating the service limit states related to concrete bridges in the American Association of State Highway and Transportation Officials’ Load Resistance Factor Design Bridge Design Specifications (AASHTO LRFD). A limit...

TRB’s Transit Cooperative Research Program (TCRP) Web-Only Document 60 and National Cooperative Highway Research Program (NCHRP) Web -Only Document 200: Command-Level Decision Making for Transit Emergency Managers describes a Transit Emergency Response Application (TERA) that is designed to train transit command-level decision makers through simulation guided experiential learning. TERA provide...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 199: Estimating Joint Probabilities of Design Coincident Flows at Stream Confluences documents procedures for estimating joint probabilities of coincident flows at stream confluences and guidelines for applying the procedures to design problems.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 198: Sag Vertical Curve Design Criteria for Headlight Sight Distance reviews the current methodologies used in the design of sag vertical curves and changes in headlamp technologies. The report also highlights potential changes to the American Association of State Highway and Transportation Officials (AASHTO) design g...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 197: Guidelines for the Load and Resistance Factor Design and Rating of Riveted and Bolted Gusset-Plate Connections for Steel Bridges explores the failure modes of steel truss bridge gusset plated connections. The report also includes a review of past literature on the strength of hot-driven rivets. The following appe...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 196: Final Research Report: A Transportation Guide for All-Hazards Emergency Evacuation documents the development of the  NCHRP Report 740 that focuses on the transportation aspects of evacuation--particularly large-scale, multijurisdictional evacuation.

TRB National Cooperative Highway Research Program (NCHRP) Web-Only Document 195: Driving Forces Influencing Future Freight Flows includes a detailed discussion on the driving forces behind high-impact economic and social changes as well as sourcing patterns that may affect the U.S. freight transportation system. An analysis of the driving forces was published as NCHRP Report 750: Strategic Issu...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 194: Traffic Law Enforcement in Work Zones: Phase II Research is contractor’s final report providing background information for the project that produced NCHRP Report 746 Traffic Enforcement Strategies for Work Zones. NCHRP Report 746 presents guidance for the safe and effective deployment of traffic enforcement strat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 193: Development of Left-Turn Lane Warrants for Unsignalized Intersections provides background on the development of NCHRP Report 745 : Left-Turn Accommodations at Unsignalized Intersections.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 192: Deployment, Use, and Effect of Real-Time Traveler Information Systems explores the deployment, use, and effect of real-time traveler information (TI) systems. The report examines transportation agency dissemination practices, assesses traveler perception and use of TI systems, and offers best practices on ways to...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 191: Analysis of Managed Lanes on Freeway Facilities evaluates the performance of managed lane facilities on freeways.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 190: Structural Design of Culvert Joints explores the effect of longitudinal bending on joints in rigid (reinforced concrete) and flexible (corrugated steel and thermoplastic) culverts. The report examines two joint types--those that release the longitudinal bending moments (denoted ‘moment-release joints’) like gaske...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 189: Design and Management of Historic Roads explores how the inherent flexibility in the current policies, manuals, criteria, rules, standards, and data sets that underlie the transportation planning and project development process may be used to preserve historic roads and roads in historic districts and settings.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 188: Survey of State Funding for Public Transportation—Ways to Improve It includes suggestions on ways to potentially improve the Survey of State Funding for Public Transportation. Areas covered by the report include definition of major terms, post-submission data checks, improved accessibility, non-transit related fe...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 187: Seismic Design of Geosynthetic-Reinforced Soil Bridge Abutments with Modular Block Facing explores design methods and construction guidelines for using geosynthetic-reinforced soil (GRS) systems in bridge abutments in seismically active regions. The report focuses on single-span, simply-supported bridges subjecte...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 186: The Superpave Mix Design System: Anatomy of a Research Program describes how the original Strategic Highway Research Program (SHRP) effort was conceived, funded, and managed. The report outlines the research and implementation efforts that brought SHRP products into routine use and summarizes some of the key less...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 184: Going the Distance Together: A Citizen’s Guide to Context Sensitive Solutions for Better Transportation is designed to help people ask the right questions at the right time during the transportation planning process in order to help ensure that transportation projects fit the context of their community. Context s...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 183: Guidance for Managing NEPA-Related and Other Risks in Project Delivery, Volume 2: Expediting NEPA Decisions and Other Practitioner Strategies for Addressing High Risk Issues in Project Delivery is designed to help in the management of the legal risks in the environmental review process for transportation projects...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 183:Guidance for Managing NEPA-Related and Other Risks in Project Delivery, Volume 1: Guide for Managing NEPA-Related and Other Risks in Project Delivery is a guide on the use of risk management as a means to help support the early identification of key issues during the National Environmental Policy Act (NEPA) proces...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 182: Appendices to NCHRP Report 693 includes a set of tables showing systems operations and management job categories, number of positions, and educational requirements for all 50 states. NCHRP Report 693 : Attracting, Recruiting, and Retaining Skilled Staff for Transportation System Operations and Management provides...

TRB’s National Cooperative Freight Research Program (NCFRP) and National Cooperative Highway Research Program (NCHRP) have jointly released NCFRP Web-Only Document 3/NCHRP Web-Only Document 185: Truck Tolling: Understanding Industry Tradeoffs When Using or Avoiding Toll Facilities. The report explores the value that shippers, trucking companies, and truck drivers seek from toll roads.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 181: Evaluation of Bridge-Scour Research: Abutment and Contraction Scour Processes and Prediction examines bridge-abutment scour and the effectiveness of the leading methods used for estimating design scour depth. In September 2012 TRB released NCHRP Research Results Digest 378: Evaluation of Bridge Scour Researc...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 180: Producing Transportation Data Products from the American Community Survey That Comply With Disclosure Rules explores approaches to apply data perturbation techniques that will provide Census Transportation Planning Products data users complete tables that are accurate enough to support transportation planning app...

TRB’s National Cooperative Highway Research Program (NCHRP) Web Only Document 179: Procedures for Verification and Validation of Computer Simulations Used for Roadside Safety Applications explores verification and validation procedures, quantifiable evaluation metrics, and acceptance criteria for roadside safety research that maximize the accuracy and utility of using finite element simulations.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 178: Assessment of Auxiliary Through Lanes at Signalized Intersections describes a project that investigated the operational, safety, and design characteristics of auxiliary through lanes (ATLs) at signalized intersections. The project resulted in the development of guidelines for the evaluation and application of ATL...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 177: Evaluation of Bridge Scour Research: Geomorphic Processes and Predictions explores the impact of long-term aggradation and degradation, and lateral river channel migration, on highway structures. In September 2012 TRB released NCHRP Research Results Digest 378: Evaluation of Bridge Scour Research , which summariz...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 176: Cost-Effective Connection Details for Highway Sign, Luminaire, and Traffic Signal Structures presents the results of research that evaluated fatigue performance of several critical welded connections in the highway sign, signal, and high-level luminaire support structures.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 175: Evaluation of Bridge Scour Research: Pier Scour Processes and Predictions explores the current state of knowledge regarding bridge-pier scour, assesses several methods for design estimates of scour depth, examines a structured methodology for scour-depth estimation for design purposes, and highlights aspects of&n...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 174: Performance Measurement and Evaluation of Tolling and Congestion Pricing Projects provides an overview of the purpose, scope, and methodology, and a complete compilation of the work products that were used to develop NCHRP Report 694. NCHRP Report 694 : Evaluation and Performance Measurement of Congestion Pricing...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 173: Cast-in-Place Concrete Connections for Precast Deck Systems offers suggested design and construction guidance for and includes five illustrative examples of durable case-in-place reinforced concrete connections for precast deck systems that emulate monolithic construction, considering issues including speed of co...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 172: Adapting Specification Criteria for Simple Performance Tests to HMA Mix Design describes the inputs and outputs of the excel based program for Integrated Analysis of HMA Mix And Structural Designs. The report also reviews the program’s underlying performance prediction models, and highlights examples that illustr...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 171: Identification of Results-Oriented Public Involvement Strategies Between Transportation Agencies and Native American Tribal Communities documents the project that led to development of NCHRP Report 690. NCHRP Report 690: A Guidebook for Successful Communication, Cooperation, and Coordination Strategies Between Tr...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 169: Determining Guidelines for Ramp and Interchange Spacing documents the research effort related to the development of NCHRP Report 687: Guidelines for Ramp and Interchange Spacing.  NCHRP Report 687 explores guidelines for ramp and interchange spacing based on design, operations, safety, and signing considerat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 168: Precision Estimates of AASHTO T 180: Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop explores an interlaboratory study and data mining of the proficiency sample program to prepare precision estimates for American Association of State Highway and Transportation Officia...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 167: Statistical Modeling of Cement Heat of Hydration Using Phase and Fineness Variables explores alternative predictive models for seven-day cement heat of hydration.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 166: Precision Estimates of AASHTO T283: Resistance of Compacted Hot-Mix Asphalt (HMA) to Moisture-Induced Damage includes the results of an interlaboratory study to prepare a precision and bias statement for the American Association of State Highway and Transportation Officials (AASHTO) T283 test resistance of compac...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 165: Precision Estimates of AASHTO T148: Measuring Length of Drilled Concrete Cores includes the results of a round robin study to prepare precision estimates for American Association of State Highway and Transportation Officials (AASHTO) T148 test method used for determining the length of a core drilled from a concre...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 164: Precision Estimates of AASHTO T265: Laboratory Determination of Moisture Content of Soils includes the results of an interlaboratory study to prepare precision estimates for the American Association of State Highway and Transportation Officials (AASHTO) T265 test method used for laboratory determination of moistu...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 163: Precision Estimates of AASHTO T267: Determination of Organic Content in Soils by Loss on Ignition includes the results of an interlaboratory study to prepare precision estimates for the American Association of State Highway and Transportation Officials T267 test method used for the determination of organic conten...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 162: Top-Down Cracking of Hot-Mix Asphalt Layers: Models for Initiation and Propagation explores mechanistic-based models for predicting top-down cracking in hot-mix asphalt layers for use in mechanistic-empirical procedures for design and analysis of new and rehabilitated flexible pavements.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 161: System Trials to Demonstrate Mileage-Based Road Use Charges explores factors to be considered in designing and implementing large-scale trials of mechanisms for collecting road-user charges based on vehicle-miles of travel.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 160 includes appendices B through N to NCHRP Report 674 : Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities, which explores information related to establishing safe crossings at roundabouts and channelized turn lanes for pedestrians with vision disabilities. App...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 159: Supporting Materials for NCHRP Report 673 contains the final report on the project that developed  NCHRP Report 673: A Manual for Design of Hot Mix Asphalt with Commentary and Appendixes C through F to the report. NCHRP Report 673 contains a mix design manual for hot-mix asphalt (HMA) that incorporates ...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 158: Field Test Results of the Multimodal Level of Service Analysis for Urban Streets (MMLOS) explores the result of a field test of the MMLOS in 10 metropolitan areas in the United States. NCHRP Web-Only Document 158 represents the third and final phase of a project that included development of NCHRP Report 616 ...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 157: Volume I: Evaluation of Existing Roadside Safety Hardware Using Updated Criteria—Technical Report explores the process that was followed in developing NCHRP Research Results Digest (RRD) 349: Evaluation of Existing Roadside Safety Hardware Using Manual for Assessing Safety Hardware (MASH) Criteria.  NCHRP RR...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 156: Optical Sizing and Roundness Determination of Glass Beads Used in Traffic Markings is the final report on a project that examined the precision and bias of both optical and traditional mechanical methods for different glass bead types. The project also compared the precision and bias of various measurement method...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 155: Design Guidelines for Durability of Bonded CFRP Repair/Strengthening of Concrete Beams explores a methodology for the evaluation of durability-related strength loss of bonded carbon fiber-reinforced polymer (CFRP) systems applied to concrete beams. The report also examines test methods to help establish a durabil...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 154: Target-Setting Methods and Data Management to Support Performance-Based Resource Allocation by Transportation Agencies - Volume III: Case Studies includes case studies of organizations investigated in the research used to develop NCHRP Report 666. NCHRP Report 666 : Target-Setting Methods and Data Management to S...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 153: A National Database of Subgrade Soil-Water Characteristic Curves and Selected Soil Properties for Use with the MEPDG is the contractor’s final report and Appendices A through D related to NCHRP Research Results Digest 347 with the same title.  NCHRP RRD 347 explores the creation of a national database o...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 152: Assessing Mechanisms for Integrating Transportation-Related Greenhouse Gas Reduction Objectives into Transportation Decision Making examines alternative methods that state departments of transportation and metropolitan planning organizations may use to manage greenhouse gas emissions from transportation.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 151: Geometric Design of Driveways includes material related to and supporting contents of NCHRP Report 659: Guide for the Geometric Design of Driveways.  NCHRP Report 659 explores guidelines related to the geometric design of driveways. The report includes driveway-related terms and definitions, an examinat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 150: Accessible Pedestrian Signals: A Guide to Best Practices (Workshop Edition 2010) provides an introduction to accessible pedestrian signals (APS) and highlights issues related to the design, installation, operation, and maintenance of APS. The report also addresses public education, U.S. case studies, and internat...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 149: Recommended LRFD Minimum Flexural Reinforcement Requirements explores the minimum reinforcement requirements for the design of concrete bridge structures and examines flexural cracking of concrete structures.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 148: Debris Photographic Archive and Supplemental Materials for NCHRP Report 653 includes the debris photographic archive, the survey questionnaire and list of respondents, and the report on the field pilot study related to development of NCHRP 653. NCHRP Report 653 : Effects of Debris on Bridge Pier Scour explores gu...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 147: Reference Materials for State DOT Title VI Compliance: Appendices to NCHRP Research Results Digest 340 includes a collection of material related to best practices that were used to help develop NCHRP Research Results Digest 340: State DOT Best Practices for Title VI Compliance .

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 146: Replacement Processes for Light Emitting Diode (LED) Traffic Signals explores the photometric requirements, measurement, and maintenance of traffic signal modules using light emitting diodes (LEDs). _______________________ NCHRP Web-Only Document 146 contains an incomplete Acknowledgments section. The complete Ac...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 145: Recommended Practice for Stabilization of Sulfate-Rich Subgrade Soils examines the nature of minerals ettringite and thaumasite, and explores the mechanism of their formation in soils stabilized with lime, cement, or fly ash.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 144: Recommended Practice for Stabilization of Subgrade Soils and Base Materials explores a methodology to determine which stabilizers should be considered as candidates for stabilization for a specific soil, pavement, and environment.

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 143: Implementable Strategies for Shifting to Direct Usage-Based Charges for Transportation Funding explores ways that direct charges to road users, based on vehicle-miles of travel (VMT), could be implemented within approximately the next 5 years.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 142: Precision Estimates of AASHTO T 242 examines precision estimates for AASHTO (American Association of State Highway and Transportation Officials) T 242, “Frictional Properties of Paved Surfaces Using a Full-Scale Tire.”

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 141: Precision Estimates for AASHTO Test Method T 104, Determined Using AMRL Proficiency Sample Data explores the use of data from the AASHTO Materials Reference Laboratory (AMRL) Proficiency Sample Program (PSP) used to update precision estimates for American Association of State Highway and Transportation Officials ...

TRB’s National Cooperative Highway Research Program (NCHRP) has released Web-Only Document 140: Precision Estimates for AASHTO Test Methods T 186, T 154, and T 22, Determined Using CCRL Proficiency Sample Data. Web-Only Document 140 explores the precision estimates for American Association of State Highway and Transportation Officials’ Standard Test Method T 186 “Early Stiffening of Hydraulic C...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 139: Precision Estimates for AASHTO Test Method T 105, Determined Using CCRL Proficiency Sample Data explores the use of data from the Cement and Concrete Reference Laboratory (CCRL) Proficiency Sample Program (PSP) that was collected from state laboratories to update precision estimates for American Association of St...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 138: Annotated Literature Review for NCHRP Report 640 includes summaries of various items that were found in the literature review associated with the production of NCHRP Report 640 : Performance and Maintenance of Permeable Friction Courses. 

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 137: Guidance for Transportation Project Management explores tools designed to potentially enhance an agencies’ transportation project management process and examines innovative way to manage a project.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 136: Performance Measures for Snow and Ice Control Operations highlights information on the current practices regarding the methods and measures used for assessing agency and contractor performance in snow and ice control operations.  Additional information on the project was published as NCHRP Research Results ...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 135: Protocols for Collecting and Using Traffic Data in Bridge Design explores a set of protocols and methodologies for using available recent truck traffic data to develop and calibrate live load models for load and resistance design factor bridge design. This report has been superseded by NCHRP Report 683: Protocol...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 134: An Experimental Plan for Validation of an Endurance Limit for HMA Pavements explores a research plan and associated cost estimate for a future study to validate the endurance limit for hot-mix asphalt (HMA) and to improve mechanistic-empirical pavement design.

TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 133 documents the research associated with the production of NCHRP Report 626 : NDT Technology for Quality Assurance of HMA Pavement Construction, which explores the application of nondestructive testing (NDT) technologies in the quality assurance of hot-mix asphalt (HMA) pavement construction.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 132: Right-of-Way Methods and Tools to Control Project Cost Escalation explores the data-gathering and analysis processes used to create a procedures guide for right-of-way cost estimating.

TRB’s NationalCooperative  Highway Research Program (NCHRP) Web-Only Document 131: Communicating the Value of Transportation Research is the contractor’s final report on the research associated with NCHRP Report 610: Communicating the Value of Transportation Research .

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 130 is an annotated bibliography that reviews several state emergency response plans associated with traffic control of rural roads in an agricultural emergency.  The material contained in Web-Only Document 130 was used to help produce NCHRP Report 525, Vol. 13: A Guide to Traffic Control of Rural Roads in an Ag...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 129, Phase 3: Pedestrian Safety Prediction Methodology explores development of improved pedestrian safety prediction models for use in the Highway Safety Manual.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 129, Phases I and II: Methodology to Predict the Safety Performance of Urban and Suburban Arterials explore the development of a draft Highway Safety Manual chapter that explore a safety prediction methodology for urban and suburban arterials.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 128, Multimodal Level of Service Analysis for Urban Streets: Users Guide explores a set of procedures for predicting traveler perceptions of quality of service and performance measures for urban streets.  Quality of service and performance are considered in terms of the needs of auto drivers, bus passenger...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 127: Performance Measurement Tool Box and Reporting System for Research Programs and Projects explores the integration of standard performance measures and tools to assist users in implementing performance measures into the Research Performance Measurement (RPM) System.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 126: Methodology to Predict the Safety Performance of Rural Multilane Highways explores a methodology designed to predict the safety performance of various elements considered in the planning, design, and operation of nonlimited-access rural multilane highways.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 125: Color Effectiveness of Yellow Pavement Marking Materials explores the range of chromaticity coordinates that observers classify as yellow and white under daytime and incandescent illumination.  A summary of the report described in Web-Only Document 125 was produced as NCHRP Research Results Digest 328.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 124: Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections documents the research efforts associated with production of NCHRP Report 613 that explores the effectiveness of geometric design features as well as signage and pavement markings to reduce vehicle speeds at high-speed inter...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 123: Evaluation of the Flashing Yellow Arrow Permissive-Only Left-Turn Indication Field Implementation explores the crash experiences associated with the use of the flashing yellow arrow (FYA) permissive only left-turn indication.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 122 explores development of a modal emissions model that reflects light-duty vehicle emissions produced as a function of the vehicle’s operating mode.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 121: Assessing and Mitigating Future Impacts to the Federal Highway Trust Fund Such as Alternative Fuel Consumption explores the impact of different scenarios on fuel consumption and fuel tax revenues.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 120: A Survey of State Practices for Protecting Transportation Agencies Against Construction and Disadvantaged Business Enterprise Fraud Including Use of Contractor Suspension and Debarment Procedures explors state department of transportation practices involving the areas of highway construction contracting, includi...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 119 contains appendixes A through C of NCHRP Report 598: Performance-Related Tests of Recycled Aggregates for Use in Unbound Pavement Layers .  The appendixes cover the literature review and background information, new aggregate tests, and surface dielectric measurements associated with NCHRP Report 598.

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 118, Part II: Incorporating ITS Into the Transportation Planning Process: An Integrated Planning Framework (ITS, M&O, Infrastructure) Practitioner’s Guidebook explores factors that are pushing regions and states towards integration of intelligent transportation systems in the transportation planning process, incl...

TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 118, Part I: Incorporating ITS Into the Transportation Planning Process: An Integrated Planning Framework (ITS, M&O, Infrastructure) Executive Guidebook explores factors that are pushing regions and states towards integration of intelligent transportation systems in the transportation planning process, including ...