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: 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) process; the effective application of management action and other resources to avoid or...

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.