ANALYSIS PROCEDURES FOR FREEWAY INTERCHANGE AREAS. HIGHWAY CAPACITY AND LEVEL OF SERVICE. PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON HIGHWAY CAPACITY, KARLSRUHE, GERMANY, 24-27 JULY 1991

The interchange of freeway traffic movements with local street networks is common throughout the United States in both urban and rural areas. While the components comprising the freeway interchange differ depending on the type of interchange configuration, most freeway interchanges include the following basic components: freeway segments, on-ramps, off-ramps, intersections, and arterial segments. Although transportation engineers have long had the ability to assess the operational characteristics of the freeway and arterial elements individually, practitioners attempting to assess the effectiveness of the interchange area as a whole have faced a dilemma. Current engineering practice in the United States is void of any analysis tool which can aggregate the various measures of effectiveness resulting from individual component analyses to an overall interchange evaluation. Like many municipalities throughout the United States, the City of Carlsbad, California faces a similar dilemma as to how to balance the integrity of regional freeway travel with effective arterial travel and access adjacent to the freeway. As a local entity, City staff have been faced with reacting to changes in interchange operations and roadway geometry which have been dictated by the State agency responsible for the freeway. In addition, City staff have been called upon to respond to local business interests wishing to develop properties adjacent to the interchange quadrants. Confronted by perceived reductions in the accessibility to the freeway due to ramp metering, plans for additional traffic demand, and requests for driveway and intersection access, City staff undertook the development of an interchange analysis guideline. This paper discusses the issues identified in the development of the interchange analysis guideline, and presents an overview of the guideline.