Analyzing the Performance of Piezo Electrical Cables for Traffic and Weight Data Collection on the National Road Network in Norway
Maximilian Franz Böhm, NTNU - Norwegian University of Science and Technology, Erlend Hoksrud Aakre, NTNU - Norwegian University of Science and Technology, Torbjørn Haugen, NTNU - Norwegian University of Science and Technology
This study evaluates the usage of piezo electrical cables for traffic data collection in Norway. The provided data sets are examined in case of their quality and used for further statistical analyses.
The collection of traffic data is an important topic within the field of traffic engineering. Especially automatically generated information about traffic volumes, speed levels and the weight of vehicles is highly welcomed. Reliable vehicle- and axle-weight data sets can be used for law enforcement purposes as well as for further statistical analyses.
In Norway, around 250 automatic speed enforcement systems are mounted all over the country. Each of them consists of a camera unit and two piezo electrical cables. A piezo electrical cable is a low cost device, which is sensitive to pressure and mounted in a depth of 25mm in the street. Besides the velocities of the passing vehicles, the systems also detect their axle weights and the axle distances. The high number of available sensors and their wide spreading across whole Norway provides a good database for creating several different nationwide statistics. However, the quality and usability of the weight data from speed enforcement systems has been unknown, and the data has not been utilized. This paper will describe the methods developed within the project for:
• automatic initial verification of data quality
• automatic weight calibration of raw data from speed enforcement systems
• use of free weather data for temperature linearization and compensation
Preliminary tests of historical data indicate that the weight data from speed enforcement systems may indeed be utilized for Weigh-in-motion (WIM)-purposes. In an ongoing large-scale test, data from several speed enforcement sites are compared with data from static weight stations and/or weight data from dedicated WIM-systems. The results from these tests will be evaluated with respect to international WIM-accuracy standards such as the COST 323 and ASTM E1318.
If successful, this project will provide the Norwegian Public Roads Administration (NPRA) with up to 250 WIM systems throughout the country, at a negligible cost. Due to the high potential benefit and low cost, the project is funded by the innovation-program of the NPRA.
Association for European Transport