LiDAR: Reflective Glass Beads make a Difference

For over 100 years, lane markings have been providing the necessary orientation in the world of road transport. But not only the human eye has to be able to detect lane markings reliably. In view of ever more complex driver assistance systems and progress made in research on automated and autonomous vehicles, machine vision is also gaining in importance.

Taking Good Decisions

One of the technologies used in machine vision is LiDAR (Light Detection and Ranging). This laser-based method enables driving systems to map the environment surrounding the vehicle and based on that, derive appropriate measures. The ability of the underlying algorithms and artificial intelligence to make good decisions hinges on the best possible detection of the lane markings. Therefore, SWARCO Road Marking Systems has been researching how modern lane markings can support such driving systems and thus increase road safety.

International Research

A joint project with researchers from Graz University of Technology in Austria and the University of Zagreb in Croatia examines the interaction of LiDAR and lane markings with different micro glass beads. At the Digitrans test center for automated driving in St. Valentin, Austria, the research team compared structured markings with SWARCO SOLIDPLUS premium reflective glass beads and plain markings with standard glass beads used as the drop-on material.

“For these tests, we chose broken white lines, but not markings in as-new condition. For the measurements, lines were used that had already been applied on the Digitrans test center’s test track over a year ago. This makes for corresponding wear and tear of the markings due to the traffic load – wear that can also be found with many road markings around the world,” explains Friedrich Wiesinger, Team Leader Product Development at SWARCO Road Marking Systems. At first, retroreflection was measured on a dry road. Retroreflection is an essential criterion for the markings’ visibility at night. The test vehicle also recorded the number of LiDAR points and LiDAR intensity of the respective markings. “These LiDAR measurements provide information as to how reliably a sensor can detect the markings,” Friedrich Wiesinger adds.

Clear Results

The results are clear: Although the high-performance markings with SWARCO SOLIDPLUS are worn, they achieve retroreflection values (RL) above 700 mcd/m²*lx. This underlines the exceptional durability of the premium reflective glass beads based on their special glass composition. The standard markings’ retroreflection values, however, remain below 250 mcd/m²*lx.

A Contribution to Road Safety

Can such a striking difference also be found between the respective LiDAR values? After analysing the data, the answer is yes. Using the premium reflective glass beads, the markings yielded twice the LiDAR intensity. In addition, the number of recorded LiDAR points was markedly higher. Like the research team, Friedrich Wiesinger therefore draws a clear conclusion: “This means that the markings with the premium glass beads are detected better by the LiDAR system used. And in the direction of travel, the high-performance markings can be detected from a longer distance. This could be an advantage for systems in automated vehicles, helping them to calculate a certain route faster.” Thanks to better detection, lane markings with SWARCO SOLIDPLUS can contribute to increasing safety in today’s complex world of road transport, too – both for humans and machines.