4 ms·

hey kgermino, Sorry to butt into the convo, but I was a summer intern at a major "traffic light" operation (for lack of a better term) in the southeast (aka, t

by Judson 16y ago

hey kgermino, Sorry to butt into the convo, but I was a summer intern at a major "traffic light" operation (for lack of a better term) in the southeast (aka, they did all of the traffic lights and systems for the southeast USA). It will seem almost shocking to many here on HN, but the traffic control industry is lagging behind drastically. I believe the newer systems started going IP based just a few years ago, and (gasp) wireless networking of traffic lights is a really new thing. It has to do with the environment the system must handle and how "tamper-proof" it must be, which leads to hardware and software being waaayy behind the curve. The main point though, is that it would be very reasonable to think that some hardware, especially if installed before the 90s, wouldn't have "software" to just "turn off monitoring". Even the newer boxes aren't completely controlled by software, they have physical circuitry that operates as a "fall-back" to make sure that things like two green lights on adjacent roads can't be green at the same time, even if the software was hacked, had a bug, etc.

kgermino 16y ago
Interesting. For whatever reason it didn't even occur to me that traffic lights would still have a "hard-wired" circuit available to operate the lights. I'm a Computer/Electrical but I tend to think in terms of coding rather than being able to solve problems with circuits. But that's interesting and makes me think I should look into an internship/coop in that area. Thanks
gecko 16y ago
Even moreso than that, many of the lights in New York still run on genuine relays. You can easily hear them at many street corners in Manhattan, happily thunking away. (The New York Subway is also still powered almost exclusively by relays, even to do complex things like monitor train speed. It's both impressive and disturbing to see what they were able to accomplish a hundred years ago without modern computing hardware.)
- lepht 16y ago
  Any recommended links on where one could read more on the NY Subway systems you mention? I'm fascinated by pre-electronic computing, and this sounds like a particularly interesting example.

by Judson 16y ago

kgermino 16y ago

Interesting. For whatever reason it didn't even occur to me that traffic lights would still have a "hard-wired" circuit available to operate the lights. I'm a Computer/Electrical but I tend to think in terms of coding rather than being able to solve problems with circuits. But that's interesting and makes me think I should look into an internship/coop in that area. Thanks

gecko 16y ago

Even moreso than that, many of the lights in New York still run on genuine relays. You can easily hear them at many street corners in Manhattan, happily thunking away. (The New York Subway is also still powered almost exclusively by relays, even to do complex things like monitor train speed. It's both impressive and disturbing to see what they were able to accomplish a hundred years ago without modern computing hardware.)

lepht 16y ago
Any recommended links on where one could read more on the NY Subway systems you mention? I'm fascinated by pre-electronic computing, and this sounds like a particularly interesting example.