Chapter 1: What is the main topic discussed in this episode?
So we are driving around Los Angeles at the best time of day, 5.41 p.m.
Vivian Leigh works with me at 99% Invisible, and she's on her way out for after-work drinks at one of her favorite bars in L.A.
And my husband Cody is driving us. I'd like to say because I'm recording, but you're driving me because what?
Because you're a passenger princess.
That's exactly correct.
Some people enjoy driving. Some people, like Vivian, really do not. But nobody enjoys being stuck in traffic. No one's moving. What are they doing?
I'm going to burn the intersection to the ground and piss on the ashes.
Oh, my God. L.A. is famously a car town, known for its endless freeways and its soul-crushing rush hour traffic. And in a city full of bad intersections, Vivian and Cody are headed towards one that many consider to be the worst. It's where three roads, Fairfax, Olympic, and San Vicente, all intersect.
I think it's technically called the Fairfax asterisk, but I like to think of it as the Devil's Three-Way, because you have this weird triangle in the middle, and there are like one, two, three, four, five traffic lights.
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Chapter 2: How did the 1984 Olympics influence LA's traffic system?
To navigate this intersection, Vivian and Cody have to make it through two traffic lights in quick succession, only a couple hundred feet apart.
Oh, God. Caught right in the middle of. Oh, no.
We are stuck in the middle. They make it through one traffic light, but then get stopped at the next one. And now they're stuck right in the middle of the triangle.
Oh, God. So there are. Oh, God. We're. Oh, boy. We are in between. Oh, my God.
I'm Delaney Hall, and this is Service Request from 99% Invisible and Campside Media. We rarely think about infrastructure until it breaks, and then suddenly it is all we can think about. So every week, we're diving into your burning questions about the invisible systems all around us. We're exploring how infrastructure works and how it's designed and maintained. Today, traffic lights in LA.
We're looking at the system behind them, meeting the people who decide when they flip from one color to another, and trying to answer the question on every LA driver's mind. Why is this red light so damn long?
Oh, you son of a bitch. Oh, you son of a bitch.
The roots of LA's modern traffic system go back to 1984, when the city was preparing to host the Olympic Games. LA was expecting more than a million visitors and thousands of athletes. Traffic in LA was bad, and all these people would be flooding into a city that was already pretty maxed out. City leaders were worried that athletes and spectators wouldn't be able to make it to their events.
You're going to the 1984 Olympics in Los Angeles, and some of your friends are asking you questions. Aren't those freeways congested? Can you find your way around? What about the smog?
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Chapter 3: What challenges do LA's traffic engineers face today?
It was an experiment and it worked. This is Salida Reynolds. She's the chief innovation officer at LA Metro. And for eight years, she ran LA's traffic light system, trying to make traffic a little bit better in one of the most traffic-y cities in the world.
There are a lot of other really interesting things that happened during the 84 games to make it such a success. But if you ask anybody who was here at the time, they will say, wow, they really solved traffic.
The first full day of Olympic competition saw a few hurdles on the massive L.A. freeway system. The games not only avoided gridlock, but the sea breezes also cooperated.
And sort of famously, when the games were over, the mayor at the time, Tom Bradley, at the closing sort of press conference said, the games are over, let the traffic begin. So, you know, there was this sort of feeling that everybody had kind of made it work for the period of the games. And now we were going to be back to our old ways.
It reminds me a little of the extraordinary measures you hear every city taking, like Beijing firing particulate into the air to make the smog like rain away before the crowds came for the Olympics. So it's interesting to me that in many ways it was one of these extraordinary measures that was taken to try to solve a problem temporarily for the Olympics. But then it continued.
Why did it continue? LESLIE KENDRICK
I think the engineers at the time were very excited by the improvements that they had seen. And they were real and measurable. They had reduced people's delay by about 30%, 35%, which in turn improved emissions, right? Because you didn't have as many people idling because you were just moving the most efficient way possible.
L.A. 's success with traffic during the Olympics made a big impact. Cities planning future Olympics called them for advice. And in the years that followed, officials from Salt Lake City and Sydney and Beijing all wanted to study what L.A. 's transit leaders had built.
As the system continued to expand, it got even more sophisticated, with new high-tech tools that could sense the conditions on the roads and then respond automatically.
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Chapter 4: How does ATSAC improve traffic management in Los Angeles?
And while it would be malpractice to say that the system has solved LA's traffic issues, it has made traffic a little less bad. 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.
And there are traffic engineers, transportation engineers and planners and other folks that are sitting in an office in downtown Los Angeles. They have hundreds of cameras that give them basically a 360 degree view of the city at any time.
And they also have a landscape view of what's happening with every single transportation signal at all of the 5,000 plus intersections that they're monitoring at any given time.
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.
Music
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.
We're moving out.
There's this scene where someone hacks into the ATSAC system to create a huge traffic jam in the middle of L.A.
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Chapter 5: What technology is used to monitor traffic in real-time?
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. The space part is pretty simple. Basically, every car, bus, bicycle, and pedestrian is competing for the same fixed space on the roads. And the reality is that engineers cannot do much to expand that space. But they can work with time.
And that's where their special algorithms come in. There is so much data collected from those sensors embedded in the pavement. And it reveals stuff like rush hour patterns and holiday surges and what a Wednesday on the road looks like versus a Sunday. And the algorithms crunch through all that information and then translate it into precisely timed traffic lights.
For the most part, those algorithmic sort of calculations for how much green time one street gets versus the other and that balancing, it's pretty fixed by the time of day and the day of the week and so on and so forth.
But there are moments when unpredictable things happen and the sensors have a certain amount of intelligence and they're able to perceive those changes and reallocate things in real time and And then sometimes the system becomes so strained that it breaks and you have to have a human in the loop to intervene and actually manage it manually.
And that human needs to be connected to all of the other humans that are there to make things work. But to move this many cars and this large of a system that has this much complexity and variation, you have to have all of those things at the same time.
That sounds like this increasingly sort of brain-breaking math problem, like how you synchronize across that many signals and how you make this intersection flow smoothly without creating chaos. That sounds so hard.
It is. And it's also, we're talking about people's lives, right? That's one of the reasons why people love transportation is because it has such an immediate effect on people's lives. And so part of what you're also doing is... trying to figure out the tolerance that exists across the system for delay or frustration. And so you're having to sort of consider how pain is being spread around.
And you're having to sort of accept that in order to balance things, everybody has to share the pain a little bit. And you're also making a judgment call. So on the main drag, there may be Let's say 45 or 50,000 people a day that are driving on that main street. On the cross streets, you have a much smaller number of people.
And so you're going to privilege the greatest good for the greatest number, right? You're going to privilege the 50,000 people on the main line. And the people on the side streets are going to experience more pain because they're going to have to wait a little bit longer. But eventually you're going to get to go.
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Chapter 6: How do traffic lights in LA communicate with each other?
Yeah, it's interesting to think about this as it's this highly engineered system. There's algorithms, there's lights, there's wires, but ultimately it is about people's time.
Yeah.
It's actually very human.
It is. I consider it as much of an art as it is a science. You know, when we move a little white line on the street, you know, six inches this way or six inches that way, we know that it changes how fast people drive or how they behave. And so it's a lot more about human behavior than it is about a math equation. Yeah, exactly. Yeah.
When we come back, 99PI producer Vivian Lay visits the ATSAC control room. Once she's there, she hacks into the system and screws up traffic across L.A. in order to facilitate the movement of a huge amount of stolen gold. Just kidding. She just wants to figure out what's up with her least favorite intersection, the Fairfax asterisk. That's when we return. Hi, good morning.
The ATSAC control room is located in downtown L.A. in a huge glass building around the corner from City Hall. It's a big space that looks kind of like a corporate meeting room with blue-gray carpet and a wall of glass windows where you can see traffic down below. But the main attraction is the huge block of screens that stretches across the front of the room.
It displays live camera feeds of intersections across the city so that engineers can keep an eye on where congestion is building up and why it's building up.
The cameras show me why it's congested.
This is Eric Zambon, a transportation engineer in charge of the ATSAC Center. He gave Vivian a tour last month and talked her through the big screen and what it allows the engineers to see.
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Chapter 7: What is the significance of the Fairfax asterisk intersection?
Okay, so green means it's online, good communication. It's running a cycle length. Right now, we're coming up on just past the a.m. peak traffic period, all right? So things are starting to slow down.
As Eric explained, most of the traffic lights were working well, and they were running their usual timing.
As the cars start to congest, it ramps up the green time to help provide throughput to get people through that area. So these are the smartest. The ones with the pink in the middle are the smartest intersections that we operate.
Could I ask you about one intersection in particular that really grinds my gears?
Of course. Are you from LA?
I am from LA. It's pretty close to me. Do you know what the Fairfax asterisk is?
That's Olympic Fairfax San Vicente. Yeah. Yeah. So that was designed well before we had... our current eyeballs yes it's so bad and there's nothing I can do about that we've we've viewed that through the lens of 50 60 years of traffic we have put that into traffic signal modeling software we've done everything we can and
I hate to say this, but the confluence of three major streets during peak hours leads to nothing but frustration and signal timing can't fix it. And we just inherited that very bizarre, geometrically bizarre intersection that has terrific signals and we have to assign right away two different streets going east-west and one going north-south. And it's proven to be a very difficult thing.
I don't know that it'll get better.
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Chapter 8: What future developments are planned for LA's traffic system?
where there'll be the same kind of setup, there'll be some cameras, there'll be some video, but it's usually for some subset of their city, some smaller, you know, maybe it's the downtown, and it's a sort of a smaller scale kind of place where things are being managed. And so it is a repeatable sort of blueprint that has become kind of state of the practice.
Okay. And then finally, another Olympics are coming. It's 44 years after ATSAC was born. Is it going to play a similar role this time around? Is it going to expand again?
Yes, absolutely. It's going to play a similar role. And we have some more tricks up our sleeve in terms of what does ADSAC 3.0 look like for the 28 games? And how can we make sure that we're moving the trains and the buses and keeping people on foot safe and getting around by bike or scooter, one of the most fun and attractive ways to do so?
Well, thank you so much, Salida. It was really fun to learn about this system. We really appreciate having you on. Yeah, my pleasure.
We're about to go through the intersection.
Back at that terrible intersection, Vivian and Cody are waiting. We're just sitting at a red light, so this might be a lot of dead air for a while.
Someone's crossing the intersection on rollerblades. Isn't that crazy?
In the dark, too.
In the dark.
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