Speaker: Dr. Roger Roess, Polytechnic University, Department of Civil and Environmental Engineering

The Highway Capacity Manual (HCM) has been a standard used in the design and analysis of highway facilities since the early 1950s. Its first edition, issued in 1950, was an early attempt to standardize design practices across the U.S. as the nation entered a period of rapid expansion of highways. The second edition, published in 1965, emphasized analysis usage, and introduces the now-familiar criteria for level of service on various types of facilities from freeways to signalized intersection?. In 1985, the third full edition of the HCM was published, with significant changes and models develope from more significant databases. An update, with changes in about 1/2 the chapters was issued in 1994.

Dr. Roess will cover changing treatments of uninterrupted flow (freeways, multilane highways), turbulence areas (weaving and ramp junctions), rural two-lane highways, signalized and unsignalized intersections arterial and other critical areas. The implications of these changes on policy and planning will also be discussed.

The subject of the presentation will be forthcoming changes in a new update, expected to he released in mid-1998, and in the full fourth edition, expected to he published in the year 2000.

Procedures have become more complex, as models are more carefully calibrated and developed. For some procedures, this has led to the need for computer analysis, as some of the models are iterative, and many are too difficult and cumbersome to do by hand.

In the year 2000, the manual will be greatly expanded to include more material on system-wide analysis planning applications, and connections to other types of model-, which may use HCM-type outputs. In addition to a paper document, a full multi-media CD, with supporting computational software, will also be released.

Dr. Roess has been a leading researcher in highway capacity methodologies since the early 1970s. As Principal Investigator on NCHRP Project Z-28B, he led the development and production of the 1985 Highway Capacity Manual. He has published over 25 papers in the area of highway capacity analysis alone, and is principal author of the text, Traffic Engineering 2nd Edition, (with McShane and Prassas) which is used in over 60 universities. A member of the Highway Capacity Committee of TRB for 12 years, he remains active as a member of several of its subcommittees. He is a principal of the project them (led by Catalina Engineering Inc. of Tucson AZ) that is managing the development and production effort for the year 2000 HCM. Since 1969, Dr. Roess has worked with Polytechnic University, Dept. of Civil and Environmental Engineering.