SMART Project: Field Test Results of Different Traffic Monitoring Technologies
P Bellucci, ANAS spA, IT; E Cipriani, S Gori, University of Roma Tre, IT; G Fusco, University of Rome La Sapienza, IT
In this paper the results of a research project are presented. This project is addressed to define requirements that traffic technologies have to fulfill when utilized in specific applications.
The recent enhancement of many features of technologies applied to traffic management systems has brought to a wide development of Intelligent Transportation Systems; such devices are so becoming more and more attractive for some monitoring applications which European national road agencies are charged of. In this regard, in Italy a research project called SMART is being carried out by ANAS (Italian national road agency); this project is addressed to define requirements that traffic devices have to fulfill when utilized in specific applications concerning different monitoring purposes ranging from traffic census to safety monitoring. University of ?Roma Tre? and University of Roma ?La Sapienza? are also involved in the main research activities related to the project.
Main scope and description
Main scope of the SMART experiment is to provide a quantitative evaluation of performance of traffic monitoring devices by defining original methodologies to evaluate measured data in terms of precision, accuracy, update rates and reliability.
The experimental site set up is located on a double carriageway road nearby Rome (Via Aurelia km 25,500) where different traffic technologies have been installed; namely: inductive loops, active infrared, triple technology (acoustic, radar and passive infrared systems), automatic video recognition, weigh-in-motion. So it has been possible to define four monitoring ?stations? with multiple devices which are under evaluation in real traffic condition for a period of one year.
The objective of the validation procedure is to characterize each testing traffic monitoring device by quantifying the divergence, if existing, between its measurement and the value of the parameter to be measured based on uncertainty theory.
This implies the comparison of testing measures with reference ones. Once the relative error of the reference measure respect to the value of the parameter to be measured has been defined, it is possible to compute the relative error of testing device for known confidence level and degrees of freedom.
In order to validate the devices above described, a reference measuring system has been set up, which is based on two technologies: Video Control and Active Infrared Laser. The former consists of two video cameras mounted on an overpass bridge that allow a continuous recording of the wide zone where detectors have been installed; vehicle counts and classification reference measures are obtained by manual control of recorded video images. The latter can detect the passage of vehicles and provide accurate measurements of vehicle speed. It is composed by a pair of infrared beams (source and receiver) mounted before and after each station to be tested. The distance between two infrared sensors is 1.7 m. In order to discriminate the lane travelled by passing vehicles, reference sensors are mounted with 30 degrees vertical incidence angle with reflectors set into innovative sealed steel boxes installed in the pavement, called Smartbox. Every laser is linked to a control centre where the time any vehicle enters the detection area of each beam is recorded so that the vehicle speed can be determined.
Weight in motion devices are validated by many passages of a reference vehicle of known weight.
Preliminary results and conclusions
Preliminary results of the SMART project have already been gathered for weight, counts, classification and speed. Such results, if confirmed throughout the whole project, are promising in characterizing the actual performance of each monitoring device and therefore the kind of application which it is better suited for.
Association for European Transport