Service Request #2: Why Is This Red Light So Damn Long?

Summary

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99% Invisible: "Service Request #2: Why Is This Red Light So Damn Long?"

March 24, 2026
Host: Delaney Hall (for this episode)
Featured Guests: Seleta Reynolds (Chief Innovation Officer at LA Metro, former head of LA’s traffic light system), Eric Zambon (Transportation Engineer, ATSAC), Vivian Le (99pi Supervising Producer), Cody Franklin

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Episode Overview

In this episode of 99% Invisible’s Service Request mini-series, producer Vivian Le and engineer Eric Zambon join Delaney Hall to unravel the design and operation behind Los Angeles’ notorious long red lights and infamous intersections. The team ventures into the heart of LA’s Advanced Transportation System and Coordination (ATSAC) center to explore:

• How LA's synchronized traffic signals work
• The complex engineering balancing act between cars, buses, bikes, and pedestrians
• The limitations of technology in a city built for cars
• The history and future of traffic management in the City of Angels

The episode addresses the burning question heard in any LA driver's mind: “Why is this red light SO damn long?”

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Key Discussion Points & Insights

1. A Relatable LA Problem: The "Devil’s Three-Way" Intersection

• [01:03–03:46]
  • Vivian Le and her husband Cody drive at rush hour through the notorious Fairfax–Olympic–San Vincente intersection.
  • The group dubs it "the devil's three-way" due to its five traffic lights and confusing geometry.
  • Quote (Vivian Le, 02:07):
    “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, 1, 2, 3, 4, 5 traffic lights.”
  • Memorable moment: Comedy and exasperation ensue as the crew gets stuck mid-intersection:
    “Oh God. So there are. Oh God. We’re. Oh boy. We are in. Oh my God.” (Vivian Le, 02:44)

2. The History: LA's Traffic System and the 1984 Olympics

• [03:57–08:50]
  • Pre-1984, LA’s traffic lights operated independently—changes were manual and reactive.
  • For the Olympics, Ed Rowe and his team created a network to control 118 lights remotely, introducing the “ATSAC” system.
  • Quote (Seleta Reynolds, 05:59):
    “It was an experiment, and it worked.”
  • After the Olympics, system metrics showed real improvements:
    “They had reduced people’s delay by about 30, 35%...which in turn improved emissions.” (Seleta Reynolds, 07:29)
  • LA’s Olympic traffic solution became a model globally—cities like Sydney and Beijing studied the system.

3. How ATSAC Works Today

• [11:09–14:41]
  • ATSAC now controls nearly 5,000 lights across the city—one of the world’s most sophisticated networks.
  • Pavement sensors at intersections send live data to a central control room.
  • The system automatically tweaks green/red cycles to best manage flow in real time, with staff able to override algorithms for emergencies.
  • Quote (Seleta Reynolds, 12:19):
    “They have hundreds of cameras that give them basically a 360º view of the city at any time... a landscape view of what’s happening with every single transportation signal.”

4. The Art and Math of Traffic Engineering

• [14:55–19:46]
  • The major constraint: LA’s street space is fixed; managing time is the only lever engineers have.
  • Algorithms analyze massive historical and real-time data to set timing by time of day, day of week.
  • Human intervention is rare but crucial in cases of major disruption (e.g., sinkholes, protests).
  • Quote (Seleta Reynolds, 17:36):
    “You’re having to 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… you’re going to privilege the greatest good for the greatest number.”
  • The system is utilitarian—but still has to account for buses, bikes, and pedestrians:
    “There’s a lot more people moving much more efficiently in the train or on the bus or even on a bike, taking up a lot less space, which, again, is one of our most precious resources.” (Seleta Reynolds, 18:56)

5. Traffic Control Room Tour: Sights and Limitations

• [22:49–26:24]
  • Vivian tours the ATSAC control room with Eric Zambon, who describes “signal Christmas trees” and live camera feeds.
  • When asked about the Fairfax asterisk, Zambon is candid:
    Quote (Eric Zambon, 25:26):
    “That was designed well before we had our current eyeballs. Yes. It's so bad. And there's nothing I can do about that… Signal timing can't fix it.”
  • Engineers optimize as much as possible, but legacy intersections remain nearly unfixable without redesign.

6. Limits of Tech and Lessons for Other Cities

• [26:33–28:57]
  • LA’s system can only do so much; the city's layout is still its greatest constraint.
  • ATSAC is a template for other cities, but most don’t have citywide coverage.
  • Quote (Seleta Reynolds, 27:45):
    “It is a repeatable sort of blueprint that has become kind of state of the practice.”
  • With another Olympics approaching in 2028, ATSAC is poised for another upgrade.

7. Human Experience: Sharing the Pain, Finding Small Victories

• [29:14–29:49]
  • Back at the Fairfax intersection, the group finally gets a wave of green lights.
  • Memorable moment (Vivian Le, 29:36):
    “Okay, we are turning left on Fairfax. Here we go. Oh, green lights all the way. Alright, that's it. Not so bad, right?”

8. Summary and Takeaway

• [29:56–31:24]
  • Delaney Hall recaps that LA’s synchronized network, managed by both algorithms and humans, offers smoother commutes—but cannot defeat geography or demand.
  • Quote (Delaney Hall, 31:24):
    “...remember, the next time you’re stuck in traffic and you are cursing the lights, know that somewhere there’s an engineer who has spent years trying to steal back seconds on your behalf, one green light at a time.”

---

Timestamps for Important Segments

• [01:03] - Rush hour journey through Fairfax/Olympic/San Vincente
• [03:57] - LA’s traffic in the 1980s and Olympic legacy
• [05:57] - System debut and Olympics success story
• [11:09] - How ATSAC operates today
• [14:55] - Human/algorithmic balancing; art vs. science in traffic management
• [22:49] - Live tour of the control room, “Fairfax asterisk” woes
• [26:33] - Transferability of ATSAC model, city limitations
• [28:34] - Looking forward: ATSAC and future Olympics

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Notable Quotes

• "No one enjoys being stuck in traffic." (Delaney Hall, 01:28)
• “It was an experiment and it worked.” (Seleta Reynolds, 05:59)
• "We reduced people's delay by about 30, 35%. Which in turn improved emissions." (Seleta Reynolds, 07:29)
• “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.” (Seleta Reynolds, 06:35)
• "You're having to consider how pain is being spread around... and you're going to privilege the greatest good for the greatest number." (Seleta Reynolds, 17:36)
• "That was designed well before we had our current eyeballs. Yes. It's so bad. And there's nothing I can do about that... Signal timing can't fix it." (Eric Zambon, 25:26)
• "It's as much an art as it is a science... it's a lot more about human behavior than it is about a math equation." (Seleta Reynolds, 19:46)

---

Tone & Style

The episode blends 99% Invisible’s classic dry wit, curiosity, and humanity. Humor, everyday frustration, and “aha!” moments keep the technical subject lively and relatable:

• Scenes from real-life LA traffic are mixed with nerdy engineering facts and metaphors (NASA mission control, “spreading the pain”).
• The show never mocks, but humanizes traffic engineers and the deeply flawed urban design they must battle daily.
• The closing is optimistic and empathetic: reminding listeners that behind every red light, there are people trying their best to make things just a little bit better.

---

Conclusion

This episode gives listeners a behind-the-scenes look at why LA’s red lights sometimes seem so long—and why technology can only do so much to smooth the ride in America’s ultimate car town. Whether you’re a local or just someone who’s sat at a red light and wondered “WHY?”, this journey through LA’s traffic control system puts a very human, often witty spin on one of urban life’s most frustrating questions.

---

Transcript

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[Vivian Le]

So we are driving around Los Angeles at the best time of day.

[Delaney Hall]

5:41pm Vivian Lay works with me at 99% Invisible and she's on her way out for after work drinks at one of her favorite bars in la.

[Vivian Le]

And my husband Cody is driving us. I'd like to say, because I'm recording, but you're driving me because what?

[Eric Zambon]

Because you're a passenger princess?

[Vivian Le]

Exactly correct.

[Delaney Hall]

Some people enjoy driving. Some people like Vivian, really do not. But nobody enjoys being stuck in traffic.

[Narrator/Announcer]

No one's moving.

[Eric Zambon]

What are they doing? Want to burn the intersection of the

[Narrator/Announcer]

ground and piss on the ashes?

[Vivian Le]

Oh my God.

[Delaney Hall]

Louisiana 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.

[Vivian Le]

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 1, 2, 3, 4, 5 traffic lights.

[Delaney Hall]

To navigate this intersection, Vivian and Cody have to make it through two traffic lights in quick succession, only a couple hundred feet apart.

[Vivian Le]

Oh God.

[Narrator/Announcer]

Caught right in the middle of.

[Vivian Le]

Oh no. We are stuck in the middle.

[Delaney Hall]

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.

[Vivian Le]

Oh God. So there are. Oh God. We're. Oh boy. We are in. Oh my God.

[Delaney Hall]

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 infrastruct 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?

[Narrator/Announcer]

Oh, you son of a bitch.

[Eric Zambon]

Oh, you son of a bitch.

[Delaney Hall]

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.

[Narrator/Announcer]

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?

[Delaney Hall]

At this time, all of the traffic lights in LA operated independently from each other. Each one had a timing mechanism that would flip the light from green to yellow to red on a regular cadence. If a traffic light broke or if an intersection got extra congested, engineers would likely find out about it from angry phone calls. And then someone from the city would have to drive out to that intersection to manually reprogram the timing mechanism of the traffic light. In the process, they would often get stuck in the same congestion they were trying to fix. But the Olympics gave city engineers the motivation and the funding to try something new. With the Games looming, a transportation official named Ed Rowie assembled a small team and they started tinkering. And what they came up with was a network that connected 118 traffic lights around the LA Coliseum into a single system for the first time. Instead of sending someone out to every congested intersection, engineers could see what was happening across a whole area and then adjust signal timing remotely in real time. The system went online just before the game started.

[Seleta Reynolds]

It was an experiment, and it worked.

[Delaney Hall]

This is Seleta 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 trafficky cities in the world.

[Seleta Reynolds]

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.

[Narrator/Announcer]

The first full day of Olympic competition saw few hurdles on the massive LA freeway system. The Games not only avoided gridlock, but the sea breezes also cooperated.

[Seleta Reynolds]

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.

[Delaney Hall]

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. 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, then it continued. Why did it continue?

[Seleta Reynolds]

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.

[Delaney Hall]

Louisiana'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 LA'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.

[Narrator/Announcer]

Los Angeles is now trying to unsnarl its traffic by applying some very advanced technology. The city has begun to plant electronic sensors beneath major downtown intersections. Those sensors determine the speed and density of traffic and feed that information to a computer beneath city Hall. The computer analyzes the information and automatically operates traffic lights to relieve congestion and speed up traffic flow. We reduced delay at intersections by about 20%. We reduced stops by 35%.

[Delaney Hall]

By the way, that last voice was Ed Rowing, who. Who died in 2023. When we come back, we'll learn about how LA's traffic system has grown since the Olympics and why it is now known as the eighth wonder of the transportation world. That's after the break.

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[Delaney Hall]

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[Delaney Hall]

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Right?

[Seleta Reynolds]

And the best part?

[Delaney Hall]

They accept Discover.

[Seleta Reynolds]

Except Discover in a little place like this?

[Delaney Hall]

I don't think so.

[Seleta Reynolds]

Jennifer oh yeah, huh? Discover's accepted where I like to shop. Come on baby, get with the times. Right?

[Delaney Hall]

So we shouldn't get the parachute pants.

[Seleta Reynolds]

These are making a comeback I think.

[Narrator/Announcer]

Discover is accepted at 99% of places that take credit cards nationwide, based on the February 2025 Nielsen report.

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[Delaney Hall]

Since 1984, the small scrappy system that started with the Olympics has grown into one of the most sophisticated traffic management operations in the world today. It's known as atsac Advanced Transportation System and Coordination, and it controls almost all of the city's 5,000 traffic signals. 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.

[Seleta Reynolds]

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.

[Delaney Hall]

So these various signals run into atsac, which I am imagining as sort of the NASA mission control center. Is that what it looks like?

[Seleta Reynolds]

Kind of, yes.

[Narrator/Announcer]

Houston, we have our truck.

[Eric Zambon]

It is number 128.

[Delaney Hall]

Selena 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.

[Narrator/Announcer]

We're moving out.

[Delaney Hall]

There's this scene where someone hacks into the ATSAC system to create a huge traffic jam in the middle of LA gridlock time. We've crashed.

[Narrator/Announcer]

It's not a crash.

[Eric Zambon]

We've got power. I can't log in.

[Delaney Hall]

And there's a shot of the ATSAC 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.

[Seleta Reynolds]

They can do that in extraordinary circumstances. So when I first got to Los Angeles, there was actually a giant sinkhole that opened up in the ground over by ucla. Less dramatic than that, there's spontaneous protests or other things happening. At that point, they're making decisions about, okay, we're going to leave this light on green for longer and clear people out of a space when they need to be redirected or rerouted.

[Delaney Hall]

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.

[Seleta Reynolds]

Yeah. Think about the way that we're managing movement through a city. You know, we're managing it in space and time and the space is limited. Right. We have 7,500 miles of streets in the city of Los Angeles. So there's a lot, but we have what we have. It's fixed so that congestion that you experience, that's too much demand for a fixed amount of space.

[Delaney Hall]

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,

[Seleta Reynolds]

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 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 in this large of a system that has this much complexity and variation, you have to have all of those things at the same time.

[Delaney Hall]

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 in an intersection somewhere else. That sounds so hard.

[Seleta Reynolds]

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.

[Delaney Hall]

Right. What I hear you saying is that it's collective and there's also something a bit utilitarian about it.

[Seleta Reynolds]

Yeah. And that goes for everybody who's using the street.

[Vivian Le]

Right.

[Seleta Reynolds]

People biking and walking as well. If there's a bus, Right, that's coming along, or a train that needs to make it across the street, there's a lot more people moving much more efficiently in the train or on the bus or even on a bike, taking up a lot less space, which, again, is one of our most precious resources. And so figuring out how to balance safety, efficiency, delay, and the sort of quality of people's lives are all the ingredients that have to go into the creativity with which the system gets managed.

[Delaney Hall]

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. It's actually very human.

[Seleta Reynolds]

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 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.

[Delaney Hall]

When we come back, 99pi producer Vivian Le visits the ATSAC control room. Once she's there, she hacks into the system and screws up traffic across LA 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.

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[Narrator/Announcer]

Oh, joy. Another day, another buzz delayed.

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Look on the bright side, you can finally catch up on podcasts.

[Narrator/Announcer]

You don't mind running late.

[Eric Zambon]

What's your deal?

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[Delaney Hall]

Get that more for your money feeling only a Metro by T Mobile. Just bring your number. $30 first month and $25 after with auto pay price guarantee exceptions apply. Seaside for details.

[Seleta Reynolds]

Ugh.

[Delaney Hall]

Could this vintage store be any cuter?

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Right.

[Seleta Reynolds]

And the best part?

[Delaney Hall]

They accept Discover.

[Seleta Reynolds]

Accept Discover in a little place like this?

[Delaney Hall]

I don't think so.

[Seleta Reynolds]

Jennifer. Oh yeah. Huh? Discover's accepted where I like to shop. Come on baby. Get with the times. Right.

[Delaney Hall]

So we shouldn't get the parachute pants.

[Seleta Reynolds]

These are making a comeback, I think.

[Narrator/Announcer]

Discover is accepted at 99% of places that take credit cards nationwide. Based on the February 2025 Nielsen report.

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[Eric Zambon]

Hi, good morning.

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Hi, Good morning.

[Delaney Hall]

The ATSAC control room is located in downtown LA 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.

[Vivian Le]

Up.

[Eric Zambon]

The cameras show me why it's congested.

[Delaney Hall]

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.

[Eric Zambon]

Is there an emergency vehicle that's blocking a lane causing congestion, or is there even a crash in the middle of the intersection? And at that point, we jump on our system and we would modify signal timing parameters to best help people get around those locations.

[Vivian Le]

Gotcha.

[Delaney Hall]

On that same big screen, there's also a map of every traffic signal in la. They show up as multicolored dots of light.

[Eric Zambon]

So that's the graphic of all the traffic signals every DOT is a node or a traffic signal, and that's our signal network. This shows in real time the status of the signals in the city. Every color represents something to us. And although it just looks like a Christmas tree to some people, it tells us the operation of the signals. Just at quick glance, we're looking at,

[Vivian Le]

you know, the layout of Los Angeles, mostly green. Could you explain to me, like, what patterns you see when you look at this? What does this actually mean to you?

[Eric Zambon]

Okay, so green means it's online. Good. Good communication. It's running a cycle length. Right now we're coming up on just past the AM peak traffic period. All right, so things are starting to slow down.

[Delaney Hall]

As Eric explained, most of the traffic lights were working well and they were running their usual timing.

[Eric Zambon]

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.

[Vivian Le]

Could I ask you about one intersection in particular that really grinds my gears?

[Eric Zambon]

Of course. Are you from la?

[Vivian Le]

I am from la. It's pretty close to me. Do you know what the Fairfax asterisk is?

[Eric Zambon]

That's Olympic. Fairfax San Vicente.

[Vivian Le]

Yeah.

[Eric Zambon]

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 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 had 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.

[Vivian Le]

Do you feel like you have to kind of just do what you can with the mess that you've been given?

[Eric Zambon]

That's exactly how I feel. Yeah. Yeah. I'm only laughing because you describe what goes on in my mind every day.

[Delaney Hall]

It's that space time problem again. As Salita Reynolds described it, the ATSAC system has improved traffic in la, but it can't control the fundamental layout of the streets or the number of people using them. It can't control the fact that LA was built as one of the most car centric cities in the world. Engineers can Play with time, coaxing millions of people through various bottlenecks. But sometimes, no matter how advanced their algorithms, it's still kind of lipstick on a pig. And they're still left with something like the Fairfax asterisk, an intersection that just was not designed to handle so many car. So I just want to understand sort of how much what we've learned about ATSAC might apply to another city. So if someone's sitting at a red light in another city, you know, Des Moines, Miami, how much of what's happening is basically the same and how much is really unique to the ATSAC system itself?

[Seleta Reynolds]

A lot of other cities will have maybe part of the city on a connected traffic management system. And most other major metropolitan areas will have a centralized traffic management center 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.

[Delaney Hall]

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?

[Seleta Reynolds]

Yes, absolutely, it's going to play a similar role. And we have some more tricks up our sleeve in terms of what does ATSAC 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.

[Delaney Hall]

Well, thank you so much, Salita. It was really fun to learn about this system. We really appreciate having you on.

[Seleta Reynolds]

Yeah, my pleasure.

[Narrator/Announcer]

We're about to go through the intersection.

[Delaney Hall]

Back at that terrible intersection, Vivian and Cody are waiting.

[Vivian Le]

We're just sitting at a red light, so this might be a lot of dead air for a while.

[Eric Zambon]

Someone's crossing this intersection on rollerblades.

[Vivian Le]

Crazy in the dark too.

[Narrator/Announcer]

In the dark.

[Delaney Hall]

But pretty soon the light changes and they start to move.

[Vivian Le]

Okay, we are turning left on Fairfax. Here we go. Oh, green lights all the way. Alright, that's it. Not so bad, right?

[Eric Zambon]

That wasn't so bad.

[Vivian Le]

Not the worst traffic we've ever been in.

[Delaney Hall]

We started with the question, how do LA's traffic lights actually work? And the answer is that the whole city is wired up. There are sensors embedded in the pavement at many traffic lights, and they connect through miles of underground fiber optic cables to a centralized control room. In that control room, engineers monitor traffic flow and make adjustments in real time. It's a system that started very small when Ed Rowe and his team faced the this impossible task, which was to keep traffic moving smoothly during the 1984 Olympic Games. And since then the system has grown, and ATSAC NOW manages nearly 5,000 traffic lights at intersections across the city. With that, consider this service request resolved. Today on the show you heard Seleta Reynolds, the chief Innovation officer at LA Metro, and Eric Zambon, a transportation engineer in charge of the ATSAC Traffic management center for LADOT. You also heard Vivian Le, supervising producer at 99pi, and her husband, Cody Franklin.

[Vivian Le]

We're going to go to our pub now. Yeah, bye.

[Delaney Hall]

What infrastructure mystery keeps you up at night? Is there something in your life that you use every day but you don't actually understand how it works? Submit your service request by recording a voice memo with your question and emailing it to servicerequest9pi.org and remember, the next time you're stuck in traffic and you are cursing the lights, know that somewhere there's an engineer who has spent years trying to steal back seconds on your behalf, one green light at a time. I'm Delaney Hall. Infrastructure is everywhere and we are here to help you decode it. Service request is a production of 99% Invisible and Campside Media. The show is produced and fact checked by Julia K. Slevine and edited by Shoshi Shmulovitz. Mix by Ewin Lai Tremuin Theme song and music by Swan Raal Show Arts by Aaron Nestor Roman Mars is our boss at 99pi. Cathy Tu is 99pi's executive producer. Matt Sher is the Executive Producer at Campside. We are part of the SiriusXM podcast family. You can find us on all the usual social media sites as well as our Discord server. There's a link to that as well as every past episode of [e-mail].

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