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 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.

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.

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.