It's pretty easy to hack traffic lights


I take Munroe’s point but I’ve gone to city hall to fight them turning my neighborhood into a literal obstacle course (the law won). I’m leaning intentional creation of congestion. :laughing: At least if I mess it up, I still have the goal of making it better and can improve it the next day.


I’m curious: didn’t Cory move to LA?

City of Los Angeles traffic signal timing is controlled by ATSAC, a system with a hardware design locked down 30 years ago when system installation began. Subsequent upgrades have been to the control center, and the software, which now uses an advanced Adaptive Traffic Control System (ATCS) that can dynamically alter cycle length, phase split, and offset in response to real-time traffic conditions; can have its base parameters tweaked to deal with temporary events; and can be manually overridden by controllers.

The Installation was finally completed just a short while back (4400 signalized intersections took a while), and further improvements will limited to increased video surveillance accessible to controllers, and further software upgrades.

I’m not sure there’s any wireless comm anywhere in the system, except maybe to the pole-top vidcams.

Which is not to say it’s unhackable, just that most of the hacks described in the article (and most of the tips here in the comments) won’t be much use in LA. (-:


Yeah, it all depends on your local gov. Beverly Hills times their lights to get people out of BH as quickly as possible, and onto someone else’s streets.

They temporarily altered it to cooperative timings after the Northridge Quake broke the Santa Monica Freeway, but then reverted to their old “jam up someone else’s streets” strategy once the broken freeway was fixed.

Burbank has always tried to be a verrrrra high-tech city, and I expect their signals run on their extensive municipal fiber-optic network, but their timings are nowhere NEAR as good as LA’s ATSAC. You can tell when you cross the border by how many red lights you hit.

I can roll halfway across the San Fernando Valley in LA without hitting a red light if I just relax and “go with the flow.”

The people stopped at the red lights are mostly the halfwits and testosterone cases who think they’ll get somewhere faster if they drive like maniacs to get to the next light while it’s still red.

But Burbank… <sigh>


Serious traffic-light hackers just install “skimmer lights” in front of the real ones.


The networking protocol is proprietary and unencrypted, and uses non-modifiable default passwords that are published online by the systems’ vendors. By default these systems have the debugging port turned on,

Jesus Christ

If a student brought me this as homework I’d see if I can retroactively make them fail earlier courses.


This would have been my question.

While debug access in the default configuration and hard-coded passwords are a big vendor fuck-up this is not an end-of-the-world-as-we-know-it finding. Sure, it can make city traffic more SNAFU, but would anyone notice this in e.g. rush-hour congestion?


On the other hand, there’s an intersection in my city where—by design—one side gets a green left arrow while the other side gets a green light. If an engineer was even involved in that decision, I doubt they even spent the time to be frustrated.


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