Evaluation of floating car technologies for travel time estimation

Travel times have been traditionally estimated from data collected by roadway sensors.Recently,new technologies,such as cell phone tracking,license plate matching,automatic vehicle identifications and video detection,are employed for this purpose.In this study,the data collected by TRANSMIT readers,Bluetooth sensors,and INRIX are assessed by comparing each to the "ground truth" travel times collected by probe vehicles carrying GPS-based navigation devices.Travel times of probe vehicles traveling on the study segment of (I)-287 in New Jersey were collected in 2009.Statistical measures,such as standard deviation,average absolute speed error,and speed error bias,were used to make an in-depth analysis.The accuracy of each travel time estimation method is analyzed.The data collected by Bluetooth sensors and the TRANSMIT readers seem more consistent with the ground true data,and slightly outperform the data reported by INRIX.This study established a procedure for analyzing the accuracy of floating car data (FCD) collected by different technologies.