Determining Lane Use Distributions Using Basic Freeway Segment Density Measures

Abstract

Lane use distribution is a useful factor in understanding the lane-by-lane variations of speed and volume on freeways. The most common lane distribution measure has been traffic volume. However, because travel speed from two conditions—congested and uncongested—corresponds to one traffic volume, this measure may provide a misleading or inaccurate assessment. This study used density measures to uniquely match traffic conditions (e.g., congestion level) and investigated lane use distributions in 2-, 3-, and 4-lane basic segments of freeways. In addition to the lane use distributions under uncongested to transition conditions, which has been addressed by previous research efforts, this study investigated lane use distributions under transition to congested conditions. A series of regression models was developed to predict lane use distributions of individual lanes that could provide information for monitoring traffic conditions and possibly predict when and how traffic breakdown would occur from a given condition. Statistical tests showed that the developed regression models from one site could be applicable to other sites that have similar roadway conditions, operational characteristics, and traffic regulations (e.g., posted speed limit).