Had similar a long time ago whilst I watched some workmen working on the traffic lights of a 6 way junction. It was being controlled by temporary lights, and they were winding up the job.

One guy with a laptop plugged into the central cabinet, and another over at the control box for the temporary lights. Temporary guy fiddled with something, put all the lights to red, and eventually everything came to a halt. Big thumbs up from him, and the cabinet guy pressed what seemed to be 'Enter' on the laptop, at which point the main lights all lit red, and then began the cycle.

We take shutdowns and startups for granted in our world, but we also expect traffic lights to work 24/7. I'd just witnessed the crossover of these two expectations, and was fascinated :-)

I once spent a slow weekend watching YouTube videos about elevators. There's a surprisingly large community of elevator nerds out there. Many fascinating videos out there on how elevator programming works (especially love the ones about old relay-based elevators https://www.youtube.com/watch?v=_xjXdjj2m5Q )

There's a fun little programming challenge set up around this if you want to try your own hand at it: https://github.com/mshang/python-elevator-challenge

> What software controls the traffic system?

One such software is SCOOT, which has been around since 1979. The name is an initialism for Split Cycle Offset Optimization Technique. All of these are traffic light jargon: the red/green split, the cycle length, and the green phase offset.

* https://trlsoftware.co.uk/products/traffic_control/scoot

> Are they difficult to hack?

Yes, in part because it involves forgetting all of the dramatized baloney that you've seen on television. It's not done from a wireless laptop in the back of a moving car magically giving the protagonists a green wave at the opportune time with zero notice and preparation.

For starters, in some places around the world much of this infrastructure was interconnected long before WiFi was even invented. There will be telecommunications lines to a central control office, and it is there that one would attack the system. Think of the original Italian Job movie, where a replacement tape at the control centre subverted the system. One would also attack it at these various roadside cabinets.

(This is not to say that no systems use radio. Several do, and their vulnerabilities are appalling. But this is not universal. And the vulnerabilities lie in things like operating systems that were invented long after computer-managed traffic light systems for cities themselves were, meaning that said operating systems are not universal either.)

* https://www.usenix.org/conference/woot14/workshop-program/pr...

Thanks for your kind words. You might like the rest of my blog. Other recent articles have discussed the price of dried maggots as a protein source, naming conventions in the Saudi royal family, the Turkish and Hebrew translations of “Joe Blow”, how plutonium-powered pacemakers work, and why you can say “redden”, “whiten”, and “blacken” but not “greenen”.

> * Can they get hacked? Of course they can… Are they difficult to hack?

http://phrack.org/issues/60/14.html#article

To know what a "puffin clearance period" is, one has to know what a puffin crossing is. More jargon, of course.