Old Time Traffic Signal Revived With A Raspberry Pi Controller

Anyone with even a passing familiarity with the classic animated shorts of the 1940s will recognize the traffic signal in the image above. Yes, such things actually existed in the real world, not just in the Looney world of [Bugs Bunny] et al. As sturdy as such devices were, they don’t last forever, though, which is why a restoration of this classic Acme traffic signal was necessary for a California museum. Yes, that Acme.

When you see a traffic signal from the early days of the automotive age like this one, it becomes quickly apparent how good the modern equivalent has become. Back in the day, with a mix of lights distributed all over the body of the signal, arms that extend out, and bells that ring when the state changes, it’s easy to see how things could get out of hand at an intersection. That complexity made the restoration project by [am1034481] and colleagues at the Southern California Traffic Museum all the more difficult. Each signal has three lights, a motor for the flag, and an annunciator bell, each requiring a relay. What’s more, the motor needs to run in both directions, so a reversing relay is needed, and the arm has a mechanism to keep it in position when motor power is removed, which needs yet another relay. With two signals, everything was doubled, so the new controller used a 16-channel relay board and a Raspberry Pi to run through various demos. To keep induced currents from wreaking havoc, zero-crossing solid state relays were used on the big AC motors and coils in the signal. It looks like a lot of work, but the end results are worth it.

Looking for more information on traffic signal controls? We talked about that a while back.

28 thoughts on “Old Time Traffic Signal Revived With A Raspberry Pi Controller

  1. Way cool restoration project. For a minute there, I thought the re-builder wanted to set up an old traffic light for inside his own home, sort of Mister Roger’s Neighborhood style, but museums are better because more people get to go by and see the re-creation. :-) …Acme, kids now days don’t believe there was ever such a company for real. :-)

          1. I don’t think pay phones ever represented a majority of phones out there so most phone books were probably well preserved (well enough anyway) with only the occasional abuse from being used to help small children guests sit up at the right level at the dinner table. :-)

  2. Controlling traffic lights was always a good example of how to use logic gates, especially for training, but nowadays SBCs have consumed also this niche.
    Interestingly, relays still persist.

        1. So instead of learning some old school skills and how things really worked the approved solution is to just to gut the device and put in a Raspberry..

          That’s not a hack, it’s butchery because it takes little in the way of skill.

  3. ….but how do autonomous cars interpret the signals?

    I wonder if there are any of these still in operation somewhere on public roads, and if a training data set could be put together… hmm!

    1. Sure, but with a PI, we can all control it over the ‘net :-)
      (actually, you can do that with an Arduino as well, you just have to work harder…and use a 2650 for the extra memory)

  4. 1. “…such things actually existed in the real world, not just in the Looney world of [Bugs Bunny] et al.”

    You should show more respect for Bugs Bunny – one of the greatest of American philosophers. Conan the Barbarian was the other truly great American philosopher.

    2. More serious tone. Does not seem to be any attempt at restoration. They gutted a historical artifact? What the hey. Will have to update that Jackson Pollock down at the museum, you know, the level abstraction is old and useless compared to modern electronic media, so we should just remove that blotchy canvass and put a nice hi-res display and drive it with a raspi in the original frame.

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