TRB's National Cooperative Highway Research Program (NCHRP) Research Report 856: Specifying and Measuring Asphalt Pavement Density to Ensure Pavement Performance examines the current state of knowledge and existing agency practices to measure and specify the in-place density of asphalt pavements. The report aims to guide agency decisions on selecting measurement methods and requirements for in-...

TRB's National Cooperative Highway Research Program (NCHRP) has released a pre-publication, non-edited version of Research Report 855: An Expanded Functional Classification System for Highways and Streets. This report builds upon preliminary engineering of a design project, including developing the purpose and need. In particular, it provides additional contexts beyond urban and rural, facilita...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 854: Guide for Identifying, Classifying, Evaluating, and Mitigating Truck Freight Bottlenecks provides transportation agencies state-of-the-practice information on truck freight bottlenecks using truck probe data rather than traditional travel demand models. The report embraces a broad definition of truck freight bottle...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 853: Guidance for Design Hydrology for Stream Restoration and Channel Stability provides written guidance and interactive tools to help hydraulic engineers assess the current conditions adjacent to a stream crossing and in the upstream watershed. Specifically, the guidance and tools provide support in assessing the curr...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 851: Proposed AASHTO LRFD Bridge Design Specifications for Light Rail Transit Loads provides proposed specifications for bridges carrying light rail transit loading, including those subjected to both light rail and highway traffic loading. The proposed specifications and design examples are based on comprehensive respon...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 850: Applying Risk Analysis, Value Engineering, and Other Innovative Solutions for Project Delivery examines the state of the art in managing project development and delivery through application of Value Engineering (VE). VE is a systematic process that combines creative and analytical techniques to achieve a common und...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 849: Strand Debonding for Pretensioned Girders provides proposed revisions to the current debonding provisions found within the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications with detailed examples of the application of th...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 848: Inspection Guidelines for Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods describe nondestructive evaluation (NDE) methods for assessing the condition of in-service post-tensioning and stay cable systems. The NDE methods outlined in this report explore different condition assessments, including corr...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 847: Variability of Ignition Furnace Correction Factors explores the significant influences that affect the variability of asphalt and aggregate correction factors for ignition furnaces. The report presents a proposed practice in American Association of State Highway and Transportation Officials (AASHTO) standard format...

TRB's National Cooperative Highway Research Program (NCHRP) Report 846: Improving Findability and Relevance of Transportation Information (Volumes I and II) provides practices and tools to facilitate on-demand retrieval of useful information stored in project files, libraries, and other agency archives. The report defines a management framework for classification, search, and retrieval of trans...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 845: Advancing Automated and Connected Vehicles: Policy and Planning Strategies for State and Local Transportation Agencies assesses policy and planning strategies at the state, regional, and local levels that could influence private-sector automated vehicle (AV) and connected vehicle (CV) choices to positively affect s...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 844: Guide for Integrating Goods and Services Movement by Commercial Vehicles in Smart Growth Environments describes policy, planning, design, and operations practices considering the coexistence of moving goods and services in smart growth environments at both the design and implementation stages as well as retroactive...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 843: Long-Term Field Performance of Warm Mix Asphalt Technologies compares material properties and field performance of warm mix asphalt (WMA) and control hot mix asphalt (HMA) pavement sections constructed at 28 locations across the United States. It explores significant determinants for each type of distress and poten...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 842: Mapping Heavy Vehicle Noise Source Heights for Highway Noise Analysis provides an analysis to determine height distributions and spectral content for heavy vehicle noise sources. The report also explores establishing and beginning the development of an extended heavy vehicle (truck and bus) noise source database fo...

TRB's National Cooperative Research Program (NCHRP) Report 841: Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments quantifies the safety benefits of four types of pedestrian crossing treatments—rectangular rapid flashing beacons, pedestrian hybrid beacons, pedestrian refuge islands, and advanced YIELD or STOP markings and signs—and presents a crash modific...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 840: A Watershed Approach to Mitigating Stormwater Impacts provides a practical decision-making framework that will enable state departments of transportation (DOTs) to identify and implement offsite cost-effective and environmentally beneficial water quality solutions for stormwater impacts when onsite treatment and/or...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 839: A Performance-Based Highway Geometric Design Process reviews the evolution of highway design, presents several key principles for today’s design challenges, provides suggestions for a new highway geometric design process, and demonstrates the value of the process through six case studies. The new process focuses on...

TRB’s National Cooperative Highway Research Program (NCHRP) Research Report 838: Guidelines for Optimizing the Risk and Cost of Materials QA Programs proposes guidelines for optimizing the risk and cost of materials quality assurance (QA) programs. It develops a methodology for establishing a materials QA program that optimizes risk and cost by providing appropriate types, levels, and freq...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 837: Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments presents emulsion performance grade (EPG) specifications for asphalt emulsions used in three pavement preservation surface treatments (PSTs): chip seal, microsurfacing, and spray seals. These EPG specificatio...

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 836: Guidelines for Emergency Ventilation Smoke Control in Roadway Tunnels presents guidelines for ventilation in roadway tunnels to facilitate human evacuation and emergency responder safety. These guidelines consider tunnel geometrics such as tunnel altitude; physical dimensions (i.e., length, cross section); type of ...