Adaptive Video-based Vehicle Classification Technique for Monitoring Traffic

This report presents a methodology for extracting two vehicle features, vehicle length and number of axles in order to classify the vehicles from video, based on Federal Highway Administration (FHWA)’s recommended vehicle classification scheme. There are two stages regarding this classification. The first stage is the general classification that basically classifies vehicles into 4 categories or bins based on the vehicle length (i.e., 4-Bin length-based vehicle classification). The second stage is the axle-based group classification that classifies vehicles in more detailed classes of vehicles such as car, van, buses, based on the number of axles. The Rapid Video-based Vehicle Identification System (RVIS) model is developed based on image processing technique to enable identifying the number of vehicle axles. Also, it is capable of tackling group classification of vehicles that are defined by axles and vehicle length based on the FHWA’s vehicle classification scheme and standard lengths of 13 categorized vehicles. The RVIS model is tested with sample video data obtained on a segment of I-275 in the Cincinnati area, Ohio. The evaluation result shows a better 4-Bin length–based classification than the axle-based group classification. There may be two reasons. First, when a vehicle gets misclassified in 4-Bin classification, it will definitely be misclassified in axle-based group classification. The error of the 4-Bin classification will propagate to the axle-based group classification. Second, there may be some noises in the process of finding the tires and number of tires. The project result provides solid basis for integrating the RVIS that is particularly applicable to light traffic condition and the Vehicle Video-Capture Data Collector (VEVID), a semi-automatic tool to be particularly applicable to heavy traffic conditions, into a “hybrid” system in the future. Detailed framework and operation scheme for such an integration effort is provided in the project report.