This report presents the results of a study to determine passenger car equivalents (PCEs) of trucks and other vehicles on urban freeways. Field data collection used the Traffic Evaluator System (TES). Samples of weaving, merge, diverge, and basic freeway sections were studied in Houston, Dallas and Atlanta. Detailed vehicle classification, headway, speed, and spacing were developed for over 287,000 vehicles.

Since 1950, the Highway Capacity Manual has been a standard used in the planning, design, analysis, and operation of virtually any highway traffic facility in the United States. It has also been widely used abroad, and has spurred the development of similar manuals in other countries. The twin concepts of capacity and level of service have been developed in the manual, and methodologies have been presented that allow highway traffic facilities to be designed on a common basis, and allow for the analysis of operational quality under various traffic demand scenarios. The manual also addresses related pedestrian, bicycle, and transit issues. This book details the fundamental development of the concepts of capacity and level of service, and of the specific methodologies developed to describe them over a wide range of facility types. The book is comprised of two volumes. Volume 1 (this book) focuses on the development of basic principles, and their application to uninterrupted flow facilities: freeways, multilane highways, and two-lane highways. Weaving, merging, and diverging segments on freeways and multilane highways are also discussed in detail. Volume 2 focuses on interrupted flow facilities: signalized and unsignalized intersections, urban streets and arterials. It is intended to help users of the manual understand how concepts, approaches, and specific methodologies were developed, and to understand the underlying principles that each embodies. It is also intended to act as a basic reference for current and future researchers who will continue to develop new and improved capacity analysis methodologies for many years to come.

TRB's National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide - Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts. This report updates the U.S. Federal Highway Administration's Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.

NCHRP Report 649/NCFRP Report 3: Separation of Vehicles - CMV-Only Lanes presents an extensive compendium of information about CMV-only lanes and examines major issues and concepts that should be understood in developing new applications of CMV-only lane concepts as a potential method for both easing congestion and reducing the number of traffic accidents on highways. Appendices to this report, including an annotated literature review, performance evaluation criteria, benefits monetization factors and unit costs, and net present value calculations for benefit-cost analysis, are available on the TRB website. This report and the supplemental information can be used by public agencies that may be considering CMV-only lane concepts in corridor studies or other planning applications. The report provides data such agencies can use to support their own evaluations of CMV-only lane projects.