Since 1950, the Highway Capacity Manual has been a standard used in theplanning, design, analysis, and operation of virtually any highway traffic facilityin the United States. It has also been widely used abroad, and has spurred thedevelopment of similar manuals in other countries.The twin concepts of capacity and level of service have been developedin the manual, and methodologies have been presented that allow highwaytraffic facilities to be designed on a common basis, and allow for the analysis ofoperational quality under various traffic demand scenarios. The manual alsoaddresses related pedestrian, bicycle, and transit issues. This book details the fundamental development of the concepts ofcapacity and level of service, and of the specific methodologies developed todescribe them over a wide range of facility types. The book is comprised of twovolumes. Volume 1 (this book) focuses on the development of basic principles,and their application to uninterrupted flow facilities: freeways, multilanehighways, and two-lane highways. Weaving, merging, and diverging segmentson freeways and multilane highways are also discussed in detail. Volume 2focuses 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 theunderlying principles that each embodies. It is also intended to act as a basicreference for current and future researchers who will continue to developnewand improved capacity analysis methodologies for many years to come.