Dynamic monitoring of traffic signs on roadways

INTRODUCTION TRAFFIC SIGNS ALONG ROADWAYS Approximately half of traffic accidents in developed countries are produced at night while only 25% of traffic movements occur at night. Traffic signs communicate regulations to us, they warn of danger and serve as a driving guide. Sign retro-reflection degrades over time, so that measuring the true value for each signal guarantees maintenance of their characteristics above roadway safety standards.

BACKGROUND STATIC MEASUREMENT Until now, retro-reflection inspection and measurement of traffic signs are carried out by static equipment that requires being in contact with the element being measured.

PRESENTATION The consortium comprising EUROCONSULT NUEVAS TECNOLOGÍAS, 3M, UNIVERSIDAD DE ALCALÁ and SAFECONTROL have developed VISUALISE: This is high-performance, dynamic equipment for monitoring traffic signs along roadways. It allows automatic determination of traffic signs and panels conditions with respect to night-time visibility.

ADVANTAGES VISUALISE has the following advantages compared to traditional retro-reflection measurement: Parked vehicles and people are removed from the area, around roadway, where measurements take place in. The measuring can be done without bulky ancillary elements needing to be handled. It increases monitoring performance, so that control intervals can be extended or the length of sections undergoing study. It provides a better knowledge about the signs state in roadway networks, thus making it possible to plan operations and hence, contribute to roadway safety in a sustained way.

OPERATION The main new technological feature of this equipment is that data acquisition is dynamically carried out while the vehicle is circulating at normal roadway speed. Visualise circulates along the roadway, acquiring panoramic images using a stereoscopic, high-resolution, digital camera system. By using an infrared illumination system during image acquisition improves the obtained results. This system employs processing software to analyse the acquired images and also incorporates a viewer for generated information handling.

OPERATION

APPLICATION VISUALISE provides the following information about traffic signs: Retro-reflection curve depending on distance. Panoramic images with sign position on the roadway. Exact reference in distance from the sign location. GPS coordinates of the sign position. Sign geometry (rectangular, circular or triangular). A detailed image of the sign undergoing testing.

EQUIPMENT COMPONENTS ELEMENTS Infrared illuminator 2.Digital cameras 3.Odometer 4.GPS 5.Keyboard 6.Control system 7.Power supply system

EQUIPMENT COMPONENTS 1. INFRARED ILLUMINATOR This illuminates up to 160 metres distance at an angle between 30º and 60º, without causing any damage or dazzling or distractions to other drivers.

EQUIPMENT COMPONENTS This is installed on one of the vehicle wheels and provides 20,000 pulses per 360º rotation of its shaft. 3. ODOMETER 4. GPS Differential, 12-channel GPS and 10-Hz frequency, with sub-metre accuracy in real-time and decimetre accuracy in post-processing. The equipment is fitted with two high-resolution and light sensitivity digital cameras. Their optics provide grey-scale images with a minimum rate of eighteen images per second. 2. DIGITAL CAMERAS

EQUIPMENT COMPONENTS 5. KEYBOARD A touch screen used to manually input significant information by an operator, during image acquisition. All references input by the operator, together with vehicle coordinate information provided by GPS are sent to the processor hardware.

EQUIPMENT COMPONENTS TFT monitor for displaying acquisition results and image recording. Processor hardware for data acquisition. Server for image sequence storage. Image processing equipment for measuring retro-reflection of the vertical sign elements along the monitored roadway section. 7. POWER SUPPLY SYSTEM Diesel generator onboard the vehicle, providing 230 Vac, with 3,500 W continuous power. 6. CONTROL SYSTEM

MONITORING AND MEASUREMENT Stage 1: DATA ACQUISITION The vehicle is used to acquire and record stereoscopic images of the roadway illuminated by the infrared system. These images are stored on hard disks without any compression for subsequent treatment and processing in the technical office.

MONITORING AND MEASUREMENT The images acquired by the equipment are analysed to produce a report containing the retro-reflection measurement of all the signs and panels along the surveyed section of roadways. Stage 2: DATA PROCESSING

DISPLAYING THE RESULTS RESULTS DISPLAY SOFTWARE 1.Data area 2.Panoramic image area 3. Monitoring results area 4. Positioning area

STATISTICS DISPLAY SOFTWARE DISPLAYING THE RESULTS

CONCLUSIONS Greater amount of data, which increases reliability and accuracy of the obtained results. Reduction of direct and indirect costs for monitoring per road network kilometre. Visualise allows repositioning operations, and maintenance of signs in significant roadway networks where it is necessary to respond to complex decisions on where, how and when intervention is necessary. It permits the prioritisation of conservation, improvement and repositioning in order to guarantee optimum road safety conditions. Detailed tracking over time of the nighttime visibility conditions of signs during their service lifetime.