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

Los Angeles traffic is legendary for all the wrong reasons, but behind the city's infamous gridlock lies one of the most sophisticated traffic management systems in the world—a network born from the 1984 Olympics that now controls nearly 5,000 traffic signals. This episode of *Service Request* from 99% Invisible takes listeners into the ATSAC control room to understand how engineers balance space, time, and human frustration, while also confronting the uncomfortable truth that even the most advanced algorithms cannot fix fundamentally flawed street design. With producer Vivian Le stuck in LA's notorious "Fairfax asterisk" intersection, the episode blends technical explanation with genuine exasperation, revealing both the ingenuity and the limits of traffic engineering.

0:00The Devil's Three-Way: LA's Worst Intersection

The episode opens with 99% Invisible producer Vivian Le and her husband Cody driving through Los Angeles at 5:41 PM—the worst possible time—headed toward what many consider the city's most maddening intersection. The spot where Fairfax, Olympic, and San Vicente converge is known colloquially as the "Fairfax asterisk," though Vivian prefers to call it "the devil's three way." The geometry is nightmarish: a weird triangle in the middle surrounded by five separate traffic lights, with two signals only a couple hundred feet apart. Vivian and Cody make it through the first light only to get trapped in the middle of the triangle when the second light turns red, leaving them stranded and helpless as cars swarm around them.

This intersection serves as the episode's central case study because it embodies everything that can go wrong when traffic infrastructure meets urban reality. The design predates modern traffic engineering by decades, and as listeners later learn, even the most advanced system in the world cannot fix it. The visceral frustration—Vivian's expletive-laden commentary as she realizes they're stuck—sets the tone for an episode that takes traffic personally.

4:14The Olympic Origin Story

The roots of LA's modern traffic system trace back to 1984, when the city faced an impossible challenge: hosting the Olympic Games in a metropolis already notorious for congestion. City leaders feared that athletes and spectators would be unable to reach events, and with good reason. At the time, every traffic light in LA operated independently, each running on a fixed mechanical timer. If an intersection became congested or a light broke, the city would only find out through angry phone calls, and an engineer would have to drive to the intersection—often getting stuck in the same traffic they were trying to fix—to manually reprogram the timing mechanism.

Transportation official Ed Rowie assembled a small team and began tinkering with a radical idea: connecting 118 traffic lights around the LA Coliseum into a single networked system. For the first time, engineers could see congestion across an entire area and adjust signal timing remotely in real time. The system went live just before the Games and worked spectacularly. Seleta Reynolds, now Chief Innovation Officer at LA Metro and former head of the city's traffic light system, notes that the 1984 Olympics are remembered for many successes, but the traffic management achievement stands out. The first full day of competition saw few delays on the freeways, and at the closing press conference, Mayor Tom Bradley famously quipped, "The Games are over. Let the traffic begin."

The system reduced delays by 30 to 35 percent and improved emissions by reducing idling. Cities planning future Olympics—Salt Lake City, Sydney, Beijing—all came to study what LA had built. What began as a temporary fix for a two-week event became permanent because the engineers were "very excited by the improvements they had seen, and they were real and measurable."

13:07ATSAC: The Eighth Wonder of the Transportation World

From that small Olympic experiment grew ATSAC—the Advanced Transportation System and Coordination—which now controls nearly all of LA's 5,000 traffic signals. The system works through sensors embedded in the pavement at most intersections that count cars as they pass. These sensors feed a constant stream of data through miles of underground fiber optic cables to a centralized control room in downtown LA, where engineers can watch a live map of traffic across the entire city.

When a street starts to back up, the system responds automatically. It can extend a green light or shorten one, nudging timing across the whole network to keep traffic flowing more smoothly. The control room itself has become legendary among traffic nerds and even appeared in the 2003 heist film *The Italian Job*, where hackers infiltrate the system to create a massive traffic jam. In reality, the room features a wall of screens displaying live camera feeds from intersections across the city, alongside a map of every traffic signal represented as multicolored dots—green for online and functioning, pink for the "smartest" intersections with adaptive capabilities.

Seleta Reynolds describes the control room as a mix of technology and human intervention. In extraordinary circumstances—a giant sinkhole near UCLA, spontaneous protests, emergency rerouting—engineers can manually override signals, leaving a light green longer to clear people out of a danger zone. But for the most part, computers make the decisions, crunching data about rush hour patterns, holiday surges, and the difference between a Wednesday and a Sunday on the road.

17:21The Space-Time Problem of Traffic Engineering

The episode's most conceptually rich section comes when Reynolds explains traffic engineering as fundamentally a problem of space and time. The space is fixed: LA has 7,500 miles of streets, and engineers cannot expand them. Congestion is simply "too much demand for a fixed amount of space." What engineers can manipulate is time, and that is where their algorithms come in.

The algorithms calculate how much green time one street gets versus another, and these calculations are "pretty fixed by the time of day and the day of the week." But unpredictable events—a crash, a special event, weather—can strain the system, and the sensors have "a certain amount of intelligence" to reallocate time in real time. When the system becomes too strained, a human must intervene.

Reynolds emphasizes that traffic engineering is as much an art as a science because it involves managing human behavior and frustration. Engineers must decide how to "spread pain" across the system. On a main drag carrying 45,000 to 50,000 people per day versus a cross street with far fewer, the utilitarian calculation is clear: privilege the greatest good for the greatest number. The people on side streets will wait longer, but eventually they get to go. This balancing act extends to all road users—cars, buses, bikes, pedestrians, trains—each taking up different amounts of space and moving different numbers of people. "When we move a little white line on the street six inches this way or six inches that way," Reynolds notes, "we know that it changes how fast people drive or how they behave."

26:04Inside the Control Room: What Engineers Can and Cannot Fix

Producer Vivian Le visits the ATSAC control room in downtown LA, located in a glass building near City Hall. Transportation engineer Eric Zambon gives her a tour, explaining the wall of screens that display live camera feeds and the multicolored dot map representing every traffic signal in the city. "Every color represents something to us," Zambon says. "Although it just looks like a Christmas tree to some people, it tells us the operation of the signals."

Vivian asks about the Fairfax asterisk, her nemesis intersection. Zambon's response is deflating: "That was designed well before we had our current eyeballs. It's so bad, and there's nothing I can do about that." He explains that the city has put the intersection through traffic signal modeling software and done everything possible, but "the confluence of three major streets during peak hours leads to nothing but frustration, and signal timing can't fix it." The intersection's bizarre geometry—two streets running east-west and one running north-south, all converging at odd angles—was inherited from an earlier era, and engineers are stuck working with the mess they were given.

This moment crystallizes the episode's central tension: ATSAC is an extraordinary technological achievement, but it cannot overcome fundamental design flaws. As Reynolds put it earlier, engineers can play with time, coaxing millions of people through bottlenecks, but sometimes it is "lipstick on a pig." The Fairfax asterisk was simply not designed to handle so many cars, and no algorithm can change that.

30:28How LA Compares to Other Cities

The episode broadens its scope by asking how unique LA's system really is. Reynolds explains that most major metropolitan areas have some form of centralized traffic management, but LA's is unusually comprehensive. Other cities typically have a system covering only a subset of their intersections—perhaps just the downtown core—while ATSAC covers nearly the entire city. The blueprint is repeatable and has become "state of the practice," but LA's scale and sophistication set it apart.

Looking ahead, the 2028 Olympics in Los Angeles will provide another opportunity for expansion. Reynolds hints at "ATSAC 3.0," which will focus not just on cars but on moving trains, buses, and keeping pedestrians and cyclists safe. The system that began as a temporary fix for the 1984 Games is now preparing for its next evolution, 44 years later.

32:07Resolution and Reflection

Back at the Fairfax asterisk, Vivian and Cody wait at a red light. Someone crosses the intersection on rollerblades in the dark—a small, absurd detail that captures the chaos of the space. Then the light changes, and they move through. "Oh, green lights all the way," Vivian says, almost surprised. "Not so bad, right?" The episode ends with a note of grudging appreciation: somewhere, an engineer has spent years trying to steal back seconds on behalf of every frustrated driver, one green light at a time.

Conclusion

This episode matters because it takes something we all experience—the maddening wait at a red light—and reveals the hidden complexity behind it. The ATSAC system is a genuine marvel of urban engineering, born from necessity and refined over four decades, yet it cannot transcend the physical and political realities of a city built for cars. The Fairfax asterisk stands as a monument to the limits of technology: no amount of algorithmic sophistication can fix an intersection that was poorly designed from the start. What stays with the listener is the image of engineers in a control room, watching a Christmas tree of dots, trying to spread pain equitably across millions of people, knowing that sometimes the best they can do is make a bad situation slightly less bad.

Key takeaways

• LA's ATSAC system, born from the 1984 Olympics, now controls nearly 5,000 traffic signals across the city using sensors embedded in pavement and a centralized control room.
• The system reduced delays by 30-35% during the Olympics and continues to improve traffic flow, though it cannot eliminate congestion in a city with 7,500 miles of fixed street space.
• Traffic engineering is fundamentally a space-time problem: engineers cannot expand roads, so they manipulate signal timing to balance demand across the network.
• Engineers use a utilitarian approach, privileging the greatest number of people on major arteries while forcing side streets to wait longer.
• The Fairfax asterisk intersection demonstrates the limits of technology: no amount of algorithmic optimization can fix fundamentally poor street geometry.
• Most major cities have some form of centralized traffic management, but LA's system is unusually comprehensive in its citywide coverage.
• The 2028 Olympics will drive the next evolution of the system, with ATSAC 3.0 focusing on moving trains, buses, bikes, and pedestrians alongside cars.