In the early 1990s, chip seal use throughout Minnesota declined to a historic low. State and local agencies were not obtaining a consistent quality of performance from the technique; however, long-term data show that successful application of chip seals extended service life of the state’s asphalt pavements by an average of 6 years.  To address the problem, the Minnesota Local Road Research Board (LRRB) funded a study by the Minnesota Department of Transportation’s (MnDOT) Office of Materials and Ro...

TRB’s second Strategic Highway Research Program (SHRP 2) Report S2-R07-RR-1: Performance Specifications for Rapid Highway Renewal describes suggested performance specifications for different application areas and delivery methods that users may tailor to address rapid highway renewal project-specific goals and conditions. SHRP 2 Renewal Project RO7 also produced: Implementation Guidelines: Volume I: Strategies for Implementing Performance Specifications: A Guide for Executives and Project Managers that i...

TRB has released the final print version of TRB Special Report 312: Transportation Investments in Response to Economic Downturns that provides guidance for federal and state officials on the best ways to use stimulus funds for transportation in the future and methods for evaluating such investments. The report examines lessons learned and impacts from the states' management of the transportation component of the American Recovery and Reinvestment Act of 2009, which provided $48.1 billion for U.S. Departm...

TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 458, Roadway Safety Data Interoperability Between Local and State Agencies provides an overview of the state of the practice regarding the interoperability between state and local safety data. The report also highlights agency practices that supporta data-driven safety program on all public roads.

TRB Transportation Research Circular E-C184: Critical Issues in Aviation and the Environment 2014 explores issues that address the major environmental components affected by aviation activities, sustainable solutions that have evolved and continue to be developed to minimize aviation’s environmental impacts, and key processes that link aviation and the environment. The focus of the e-circular is on the state of science and on identification of priority research with potential to yield benefits during the...

TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 457: Implementation of the AASHTO Mechanistic-Empirical Pavement Design Guide and Software documents the experience of transportation agencies in the implementation of the 2008 American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide: A Manual of Practice (MEPDG) and the 2011 software program, AASHTOWare Pavement ME DesignTM (formerly DARWin-ME). The MEPDG and accompanying ...

TRB’s Transit Cooperative Research Program (TCRP) Synthesis 109: System-Specific Spare Bus Ratios Update documents successful practices in the United States and Canada, and presents information on efforts employed to achieve optimal bus fleet size and effective spare bus ratios. The synthesis is designed to provide guidance to transit agencies on how various factors may affect optimal fleet size. Appendix D: Compilation of Agency Survey Responses was not printed not included in the print or PDF version o...

A featured story in the January-February 2014 TR News explores how some transportation agencies used assistance of the Clear Roads program to face the logistical challenge of clearing ice and snow to keep roads passable and safe. The Clear Roads program leverages state members’ contributions to fund research about new techniques and technologies, avoid duplication of effort, influence the private sector, engage in technology transfer, inform the public, and partner with other research groups.

The National Research Council has released a report that analyzes and provides options for improvements to the certification and compliance procedures for medium- and heavy-duty vehicles; reviews an updated analysis of the makeup and characterization of the medium- and heavy-duty truck fleet; examines the barriers to and the potential applications of natural gas in class 2b through class 8 vehicles; and addresses uncertainties and performs sensitivity analyses for the fuel consumption and cost/benefit es...

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 state is defined as the boundary between acceptable and unacceptable performance of the structure or its compon...