The idea is simple and two-fold: to advise drivers on what speed to maintain to get smoothly through the next green light, and to give those stopped or almost stopped an idea of when a red light will next turn green.
Using common infrared technology (that's virtually weatherproof at these short distances), the so-called Green Wave system receives information from transponders on traffic lights, regarding light timing, and a processor in the vehicle interprets the distance ahead and calculates a proper speed to match up with the next green light.
In a brief test at Honda's research and development facility in Tochigi, Japan, last week, we were able to experience the Green Wave system in use, through a series of two traffic signals outfitted with the new hardware and a Japanese-market Honda Odyssey fitted with the interface.
Helps get the timing right
As we experienced, after accelerating to speed, a dash display provided a recommended driving speed in order to get through the upcoming traffic light while it's green. There's even a recommendation on when you can take your foot off the accelerator, so as to coast to a stop in a smoother manner.
When you're approaching a red light (or already at it), the in-dash display also gives you a 'remaining time' countdown bar graphic, allowing you to coast slowly up to the light and ease gradually back onto the accelerator when the light turns green.
In Japan, according to one of the engineers involved in the project, there are already tens of thousands of intersection transponders installed for traffic monitoring and emergency vehicles, and it would simply require that a second transponder for the green wave technology be placed next to them. In the U.S. as well, the system could be installed and maintained along with the network of optical beacons mounted near traffic signals and aimed toward traffic information-gathering and signaling for emergency vehicles. Green Wave, or something like it, is probably about three years away from a larger deployment, still in a few select metro areas, in Japan, the U.S., and Germany.
Better fuel efficiency, fewer accidents
According to Honda, and based on analysis from ITARDA fiscal-year 2011 traffic-collision data, the Green Wave system could considerably reduce rear-end collisions—especially those involving rapid stops from poor judgment, inattention, or operator error. Fuel efficiency could be greatly improved in urban or suburban areas as well with such a system. Based on a limited test in an urban-Tokyo setting, Honda found that the system provided a nearly seven-percent gain in km/L (or mpg), overall.
The only thing that we, along with several colleagues, wondered after experiencing the system, concerned implementation: It may be even more annoying than not knowing the timing of the lights, to be following a Green Wave vehicle that, to those not in the know, would appear to be driving somewhat erratically, or inexplicably slow.
As we've reported in the past, BMW and Audi are both also among the companies working on such technology, which is likely the next step on the way toward a centralized Intelligent Transportation System (ITS) that would involve V2I (vehicle-to-infrastructure) communication capable of tracking individual vehicle trajectories and warning drivers of possible collisions or hazards.