“Inadequate and poorly maintained signs and markings are often cited as the contributing factor to accidents. While only 25% of travel occurs at night, about 55% of fatal accidents occur at night.”
US Federal Highways Administration
Safe traffic conditions depend on adequately performing traffic signs and road markings. At night on dark roads, the retroreflection created by traffic signs and road markings is essential to guiding drivers in keeping vehicles safely positioned on the roads, thereby avoiding or at least reducing the number of traffic accidents.
During wet and rainy weather, even high-performing traffic signs and road markings present a challenge, as water often partly or fully covers the reflective surfaces, reducing or eliminating retroreflectivity.
In short, retroreflection is a crucial parameter in understanding how road visibility can be improved. It is about how we maximise the light from vehicle headlights being returned back along the same path it came from, maximising the driver’s visibility.