Fluorescent paint for roadway lane-markers

As a compromise between unaided and fully automated driving, we have been investigating the concept of "sensor friendly highways and roadways". In this paper we report our work in this context with fluorescent paint for roadway lane-marking lines. The approach we envision is to add one or more fluorescent pigments to the lane-marking paint, or possibly to the retro-reflective glass beads that are typically sprinkled on the wet paint immediately after its application. Vehicles would be equipped with light transmitters and receivers at the appropriate fluorescence excitation and emission wavelengths. In the simplest embodiment, e.g., as a sensor that detects just lane departure, an annunciator would inform the driver whenever a lane boundary line is crossed. In more complex embodiments, a small code space could be created by using mixtures of several pigments and measuring the relative signal intensities at the corresponding excitation and emission wavelengths. A few bits of local information could thus be encoded in the lane-marking lines, for example, the line identity (e.g., it is the roadway edge line, or the centerline, or the border-line between the second and third lanes, etc.), or some important feature of the roadway (an exit ramp is a short distance ahead, etc.). If the technology provides only minimal signal-to-noise margin it may be feasible to probe only the lane-marking line immediately alongside the vehicle, or only a short distance ahead, but if there is "signal to burn" it will be possible to look correspondingly further ahead of the vehicle. With adequate signal-to-noise it would be possible also to use fluorescent paint technology to mark roadside obstacles, e.g., sign and luminaire posts, so as to cooperatively eliminate them as clutter in a collision warning radar signal stream. Our experiments and analysis indicate that the method is technically feasible given a few plausible improvements in fluorescent materials technology, and economically viable given reasonable assumptions about the cost of vehicle instrumentation and roadway treatment.