Application of Regression Analysis for Identifying Factors That Affect Seasonal Traffic Fluctuations in Southeast Florida

Traffic variations occur at different time scales—time of day, day of week, and season of the year. Among the known temporal fluctuations of traffic stream, seasonal variation is probably of the most concern in traffic monitoring. In the current practice of the Florida Department of Transportation, district offices determine seasonal factor categories from a group of selected permanent telemetry traffic monitoring sites and assign them to short-term traffic count sites for estimating annual average daily traffic. Assignment of short-count sites to factor groups is based largely on their spatial proximity to a permanent traffic count site and engineering judgment. Although location may be an important factor, this process may be oversimplified and somewhat subjective. Regression analyses for estimating seasonal factors shed light on the factors contributing to seasonal changes in traffic volumes. The method could reduce the subjectivity of current practice either by allowing seasonal factors to be estimated directly for each short-count station or by providing guidance for assignment of seasonal groups to short-term counts.