Vivian Lay

Believe it or not, without this system, the streets of LA would be even more clogged.

The way it works is that there are sensors buried in the pavement at most intersections across the city, and they count cars as they pass.

The sensors feed a constant stream of data back to a control room in downtown LA, where engineers can watch a live map of LA traffic.

When a street starts to back up, the system automatically responds.

It can extend a green light or make one shorter, nudging timing across the whole system of intersections to help traffic flow more smoothly.

So these various signals run into ADSAC, which I am imagining as sort of the NASA Mission Control Center.

Is that what it looks like?

Kind of, yes.

Houston, we have our truck.

It is number 128.

Selina told me the ATSAC control room has become legendary among traffic nerds, and it's been featured in a couple of movies, including a 2003 heist film called The Italian Job.

There's this scene where someone hacks into the ATSAC system to create a huge traffic jam in the middle of L.A.

And there's a shot of the at-sat control room in the movie with engineers holding their heads in their hands, staring at these enormous screens that show intersections across the city.

They're totally freaking out as cars smash into each other and traffic descends into chaos.

So in that control room, you're saying it's a mix of technology and human intervention to make the signals change.

So in some cases, there's a person pressing buttons, flipping switches, and making the lights change?

But these are mostly extraordinary circumstances.

For the most part, it sounds like there are

computers that are making decisions about when to flip from green to yellow.

I like this idea that traffic engineering is all about space and time because it elevates what seems like a mundane discipline into something a little more epic.