A Performance Evaluation of Automatic License Plate Recognition System for High-Speed Vehicles on Burapha Withi Expressway

Abstract

Expressway Authority of Thailand (EXAT) has a plan of developing the toll collection system by implementing the technology of Multi-Lane Free Flow (MLFF) to the expressway system. MLFF is a new Electronic Toll Collection (ETC) system that applies Automatic Vehicle Identification (AVI) system with Automatic License Plate Recognition (ALPR) system. Therefore, ALPR system with supporting high-speed vehicles has been tested the accuracy and efficiency of detecting the vehicles on expressway, comparing with ALPR system without supporting high-speed vehicles by installing 1) ALPR Camera 2) Microwave Radar Sensor and 3) Vehicle Detector on gantry at Sta.32+500 with the direction of heading to Bangna on the Burapha Withi Expressway. The results of ALPR system testing both day time and night time indicates that the vehicle detector can detect a total of 80,364 vehicles which is divided into 31% of vehicles for speed with higher than 120 km/h, 58% of vehicles for speed with between 100-120 km/h and 11% of vehicles for speed with less than 100 km/h. The accurate number of ALPR system with supporting high-speed vehicles is 76,291 vehicles or 94.93%, and the accurate number of ALPR system without supporting high-speed vehicles is 41,740 vehicles or 51.94%. Due to the result of this study, it shows that ALPR system with supporting high-speed vehicles will be applicable for MLFF in the future.