Coming up: Cars and Traffic Lights that Communicate


There are smart roads, and there are smart cars. The next step in the evolution of the digital city is smart cars that communicate with the smart roads.

As Jennie Xie writes for Atlantic Cities, there is considerable innovation in traffic signals these days. An increasing number of signals are synchronized to accommodate changing traffic flows during different times of day, week and year. Some are programmed to respond to changing conditions in real time. Meanwhile, new cars are rolling off the factory floor equipped with sensors and control systems designed to prevent inattentive drivers from drifting across lanes or tailgating too closely.

What if the traffic signal sent off a message telling cars when the light was about to change? In theory, cars could adjust their speed to reach the intersection when the light was green. If the traffic signals were networked, people could drive a lot farther before encountering a red light.

Automaker Audi is testing such a technology in Berlin and Ingolstadt in Germany and in Verona, Italy. And in Oregon, Texas and Utah, Green Driver is testing a mobile app that uses data from city traffic management systems to offer signal prediction regardless of the car being used.

The technology could well reduce congestion, concludes Xie, but there are safety concerns. It could cause problems if lights start changing unpredictably, if drivers speed up to catch lights, or if drivers pay more attention to the technology displays than to the actual road conditions around them.

Let’s hope that someone deep in the bowels of the Virginia Department of Transportation is paying attention to this trend. The time to pilot-test these new technologies is now.


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16 responses to “Coming up: Cars and Traffic Lights that Communicate”

  1. I’m convinced from driving in Fairfax County that VDOT only uses timing and does not synchronize most signals. I regularly experience my light turning green; traffic moving toward the next intersection; and experiencing a red light. It’s the “hurry up & wait” method.

    1. LifeOnTheFallLine Avatar

      Why are you assuming yours is the priority corridor for optimization?

      1. Route 7 is not the priority corridor? Ditto for International Drive.

  2. there are several kinds of “syncing” going on these days and there are different aspects to it.

    For instance, some lights and series of mainline lights can operate on a program that is basically historical data … like weekday non-rush hour or week-day rush hour or weekend “programs” …but the signals are not operating in real time and sensing the flow.

    so those lights are operating based on what the historical data shows that is typical for that time of day and if that’s different from some reason.. then the lights do not adapt.. they just do what they were programmed to do.

    those light are particularly not good at left turns.. since they cannot “see” whether this is one car waiting or ten… and if it’s been programmed to be one of series of lights in a string that are supposed to all stay green.. then it’s not going to give a left green anyhow – otherwise the whole idea of keeping several lights in a row – green – just goes to hell in a handbasket.

    the newest generation are “networked” and sense in real time and can adapt to changing traffic conditions but these are just beginning to be implemented and are using technology akin to what the “smart” cars are using and there are concerns … about what the fall-back is if for some reason the computer network goes belly up.

    for regional networked signals.. I don’t think cars being able to communicate with lights is a viable thing.

    It might be at a single “dumb” light not on a network with other lights but can you imagine hundreds of cars trying to “sense” what the lights are doing and doing something in particular? Or maybe I’m messed up and don’t see the potential benefit.. It just seems if the signals are being operated by a computer that senses traffic.. that it’s out of the hands of the vehicles and it’s better off out of their hands.

    1. VDOT and any other public entity has access to the 4.9GHz public safety radio band subject only to frequency coordination. WQKF201 is licensed to VDOT, but for the two I-64 rest stops in New Kent County only. It is a great set of frequencies for point-to-point and point-to-multipoint connections. With all the software companies in NoVA, one would think someone could allow signals to talk to other signals and a master server and vice versa.

      Tysons would be a great place to experiment.

  3. LifeOnTheFallLine Avatar

    This is great news! For years, traffic engineers have timed lights on a corridor so that at specific speeds drivers could ride the green wave. The problem is, most places that information is never explicitly passed along to the driver, who instead is supposed to figure that out for herself and speed up or slow down accordingly. This sort of communication would go a long way toward helping to get the desired results from such timings.

    And I spoke very broadly above…this sort of thing is not happening on every corridor.

  4. Maintain 7 mph over the speed limit and you are home free. Or you can do like I do and drive 4 mph less. That way you get to see the driver behind you slam on his breaks and go into meltdown as you barely sneak through the light. πŸ˜‰

  5. you’re a stinker Darrell!

  6. Whaaat?

    You never heard of ridge runner relational calculus? It’s naturally ingrained in the minds of those who learned to drive fast in the sticks while not learning a damn thing in school. The unique ability to maintain ‘as the crow flies’ time while driving the awfullest snakeback dirt road you’ve ever seen in your life. A genius equivalent of completing a Rubik’s cube in under one minute with one hand, while chugging a PBR 40 with the other.

    Ok, that last one might not have been too smart. But I’ll betcha that from now on you will have serious second thoughts about that guy in front of you with the WVU sticker on his rear window.

  7. billsblots Avatar

    “Let’s hope that someone deep in the bowels of the Virginia Department of Transportation is paying attention to this trend. The time to pilot-test these new technologies is now.
    – JAB”

    Let’s wish someone was paying attention to what VDOT is doing. For more than a year VDOT is one of several organizations nationwide testing Digital Short Range Communications (DSRC) between pilot cars in Fairfax and roadside communications units, now referred to as Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications. These do not communicate on 4.9 GHz, rather the Federal Communications Commission (FCC) allocated 5850 – 5925 MHz (5.9 GHz) band. This communications link between vehicles and infrastructure will tie together the very things being discussed, as well as fog detectors on Afton Mountain, ice sensors on the road, Roadside Weather Information Systems (RWIS), and other inputs. Flexible and dynamic coordination of traffic signals would be one of the products of such real time communications, as well as alerts of suddenly stopped traffic ahead communicated to the car and driver in time to avoid slamming into the backside of the car(s) stopped ahead of you.

    This V2V / V2I has been piloted in Ann Arbor with volunteer cars for a couple of years, and in Fairfax also with over 40 Infrastructure sites. I am unsure how many cars have the communications units.

    Unfortunately, the push from the White House to the FCC is to establish greater wi-fi speeds, and in order to accomplish that, wider contiguous chunks of frequency spectrum must be allocated and classified by the FCC for those type of emissions. The primary target for conversion to giga wi-fi lies in 5 GHz including the aforementioned 5.9 GHz DSRC band. These two are highly incompatible given current communications protocols. The Electronics Industry Association, producers of communications chips and wireless routers see another virtual gold mine once this new band and communications standards are passed. They promise that they can develop wi-fi standards allowing for “interference mitigation” so that life-saving, collision avoidance messages on the same frequencies will not be blocked. Not likely.

    National Telecommunications and Information Administration (NTIA) and the FCC are studying this issue and have received hundreds of comments from interested parties. Not surprisingly there are more commercial interests supporting the authorization of wi-fi to the 5.9 GHz band than government, safety and auto interests requesting the FCC go slowly and require proof that wi-fi will not block critical, time-sensitive V2V and V2I communications.

    The communications medium necessary to allow the dynamic traffic signal management you all crave, among many other benefits, is present and international auto and government agencies have been working for ten years to establish standards and produce equipment for testing its viability. At the 11th hour it may all be rendered useless by a national government that cannot maintain priorities.

    Life-saving collision avoidance and advanced traffic management, or higher speed wi-fi to watch espn highlights while eating breakfast at IHOP, your call.

    1. I am heartened to hear that VDOT is working on these communications technologies. Thanks for the update. I’ve been out of the loop for a year or so, since I stopped attending CTB meetings and covering transportation as closely.

      Sounds like the behind-the-scenes work at the federal level is the usual special-interest slugfest. May the man with the most lobbyists and biggest campaign contributions win!

      1. billsblots Avatar

        I’m sure that’s what will happen in the end! Government, transportation, and industry, and Intelligent Transportation Systems (ITS) America and international took too long getting something working to the test stage. Frequencies were allocated by the FCC more than 12 years ago. Nature abhors a vacuum and the FCC abhors unused spectrum. Private wireless industry will put the spectrum to use much quicker, but it may not be in the best long term public interest.

        1. Unused spectrum is simply unacceptable, at least until we obtain significant use of cognitive radio technology. If spectrum sits idle for 12 years, there’s no reason it should not be reallocated. The 4.9 GHz frequencies remain available. Moreover, the public safety industry and its consultants are working on a new set of rules for 4.9 that can provide more value to public safety operations.

    2. re: ” At the 11th hour it may all be rendered useless by a national government that cannot maintain priorities.”

      While I appreciated the narrative, I suspect this and the WH viewpoint are more editorial than reality…

      unless the situation is that all other countries have gone forward and not had this problem.

      there are conflicts with the spectrum… and each industry lobbies for what they think belongs to them.

      Let me give an example:

      ” LightSquared is a company that seeks to develop a wholesale 4G LTE wireless broadband communications network integrated with satellite coverage across the United States using a block of frequencies located near the band used by the Global Positioning System (GPS). However, the issue of interference (using high-powered ground transmitters in spectrum intended for low-powered signals from satellites) has caused problems.”

      “On February 14, 2012, the U.S. Federal Communications Commission (FCC) moved to bar LightSquared’s planned national broadband network after being informed by the National Telecommunications and Information Administration (NTIA), “the federal agency that coordinates spectrum uses for the military and other federal government entities,” that “there is no practical way to mitigate potential interference at this time.”[1][2] LightSquared is challenging the FCC’s action.”

      The FCC action essentially resulted in LightSquared filing for bankruptcy.

      Now there are a couple of ways of looking at this and one of them might be to blame the WH for telling the FCC to “unfairly” restrict this company…

      I don’t buy it – … it’s the normal back and forth between various companies and industries seeking spectrum…as Jim B posits…

      perhaps the bigger question worth contemplating is what would happen if there was no Govt control of the spectrum?

      would that work?

      Light Squared had a brilliant innovation – and probably one that it’s competitors will want to some day expand to – and without spectrum won’t be able to – unless something changes…

      how that happens – or not.. ends up with different points of views as to who and who.. but blaming the WH is probably not on point…

  8. Hmm… Wonder what a pencil beam from 120 miles up could do to traffic management?

    1. billsblots Avatar

      I’m not sure, but I do know that a pencil-necked geek can really screw up traffic management ! πŸ™‚

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