194 | SAFETY
Safety visions Improving traffic sign visibility is critical to improving safety for road users Words | Nikhil Agashe, Avery Dennison R&D director In 2016, according to a report from Macquarie Bank, 88.1 million cars and light commercial vehicles were sold worldwide, up 4.8% from a year earlier. This upward trend is expected to continue, and with that comes the critical need to ensure that roads remain safe for the millions of people that use them each day. As people in most developing countries are now realizing their dream of car ownership, the additional burden on capacity is increasing. Construction of new roadways has failed to keep pace with this growth.
Shared space roadways In every country across the globe, the urban roadway is a shared space, with automobiles, public transportation vehicles, motorcyclists, cyclists and pedestrians traveling side by side. In developed countries, there is a movement to research, develop and introduce alternate transportation options and greater safety measures as the roadways become more crowded. In any of these scenarios, drivers must become more alert to, and aware of, their roadway surroundings, to improve safety on the roadways. States, counties, cities, townships and their road authorities also have an increased responsibility to provide better solutions to drivers facing more road chaos and congestion. One such solution is the improved visibility of traffic signs. In many locations, fluorescent material is frequently used to mark pedestrian crossings, bicycle pathways, walkways and other informational signs. Fluorescent colors are used widely because they improve the appearance of the sign, and because of their brightness, make it more visible. Fluorescence is a phenomena where radiation is absorbed by a fluorophore (usually a pigment, dye or other colorant), resulting in excitation of the fluorophore species. As the fluorophore returns to its original ground state, it releases a lower energy, or higher wavelength radiation.
Intertraffic World | Annual Showcase 2018
The choice of the fluorophore or the combination of multiple fluorophores is critical to the performance of fluorescent colors. ‘Performance’ is defined as the level of fluorescence, color or hue, and longevity or durability of fluorescence. Innovating to increase the durability of fluorescent materials used in traffic signage is especially important given the fact that fluorescent colorants have poor ultraviolet light stability.
Limiting light exposure In some instances, fading of fluorescent sheeting due to ultraviolet (UV) light exposure dramatically shortens the useful life of the sign. While UV screening or blocking is one solution intended to address the outdoor durability problem, several difficulties can arise.
One concern is that the UV light-absorbing compounds of these screening layers can leach out in time or can diffuse or migrate into the underlying fluorescent layer. This diffusion can actually accelerate fading of the fluorescent colorant in certain instances.
On the frontline of developments The engineers at Avery Dennison are at the forefront of solutions that maximize the fluorescent colors’ performance in international traffic signage. After continuing evaluations and regular trials, Avery Dennison optimized the pigment and dye chemistry for the most durable and visible traffic signage applications. The fluorescent materials provide improved fluorescent coloration articles
