The automatic, dynamic and high performance inspection system, VISUALISE, developed by Euroconsult in collaboration with the Robesafe Research Group at the University of Alcalá (Spain), has been evaluated at the prestigious Texas Transportation Institute during May, achieving a positive assessment of its ability to measure the state of the vertical signs according to its retroreflectivity values.
VISUALISE is a patented dynamic inspection system for traffic signs, mounted on top of a vehicle, which is able to perform inspection tasks at conventional driving speed using computer vision techniques. This system provideswith retroreflectivity values for the different colors on the background and legend of road signs (including those panels above the road).
This system allows for an improvement in the awareness of the road signaling state with regard to retroreflectivity values, supporting planning and decision making on the administration’s and infrastructure operators’ side. VISUALISE leads to a series of advantages versus the traditional means based on static handheld devices,including inspection cost reduction and the avoidance of survey hazards due to the presence of people and vehicles beside the roads.
VISUALISE system is based on the light retroreflection principle. It uses an active illuminator whose features are perfectly defined and known beforehand as a pattern light source. The light is reflected by the signs and panels and captured by a stereoscopic system made up of two high-resolution cameras.
VISUALISE system has been evaluated at the Texas Transportation Institute to assess the measurement bias and repeatability of sign retroreflectivity measurements. The van readings were compared with those from a calibrated handheld retroreflectometer. More than 100 signs were used within the different tests, including shapes and less uncommon colors at Spain, such as rhombus and yellow backgrounds. Measurements were carried out for an input angle of 0.2º and an observation angle of -4º, showing the system its capability to adopt American signposting regulations.
A static test was conducted on a closed-course facility to determine the accuracy of the real-time retroreflectivity measurements, achieving impressive results [Reference TTI report]. Dynamic test carried out on both a closed-course testing facility and along an open-road route, showed that van measurements are even more repeatable than handheld measurements. The open-road testing is the most challenging one and what really counts. VISUALISE measurements are obtained from the roadway and provide a better realization of how the sign is actually seen from the perspective of the driver. The findings indicate that the system is functioning as it should. Hence, the mobile measuring system is able to provide a good representation of how the signs are working at night.
Based on the results, Dr. Paul Carlson, head of TTI Operations and Roadway Safety Division, has stated: “VISUALISE is a feasible tool for measuring traffic sign retroreflectivity for compliance with the minimum maintenance requirements in the MUTCD”