Abstract
As a part of the research project gap acceptance and traffic interaction in the freeway merging process, field studies for the collection of data were performed on nationwide basis at a number of selected entrance ramps, utilizing an aerial photographic technique. This technique, the data reduction methods and the study sites selected are described in detail. Data editing routines and the analysis of the data for basic traffic parameters are discussed and some of these parameters used to illustrate the merging operation at each study site. The qualitative effect of various geometric elements on the operation as mirrored by the traffic parameters of volume, density, speed and acceleration noise are discussed.