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Traffic on Seattle's Mercer St at rush hour (Photo by GeekWire/K
Rush hour traffic on Seattle’s Mercer Street, north of the Amazon headquarters, approaching Interstate 5. (GeekWire Photo / Kevin Lisota)

Growing pains hurt the most when you’re at a standstill.

Just ask Nile Nelson. The longtime Seattle resident has commuted to the burgeoning South Lake Union neighborhood for 10 years, experiencing the ups and downs of construction over time in a congested traffic corridor known to locals as the “Mercer Mess.”

The senior product manager has worked in South Lake Union for five years, but he has endured Mercer Street for almost 10, since his daughter’s ballet studio sits by Seattle Center.

Without traffic, his drive from North Seattle takes as little as 15 minutes. More often, however, he sits in his 2011 Subaru Outback for 30-40 minutes — if his daughter catches a ride to school and they can use the carpool lane. “If I’m solo in the morning, then 20-30 minutes can easily be added [by] using the Mercer exit,” he said.

He considers taking the bus, or even biking the eight miles to work, but with a daughter at school and a Golden Retriever in dog daycare, it’s not always an option to take those alternatives. Plus, with a high-demand job, he’s often taking conference calls while en route home. So he drives.

“It can take up to an hour to get home after picking my daughter up [around 6 p.m.],” said Nelson. “The majority of my commute time, sometimes 45 minutes, is spent on Mercer.”

One day, the drive took an hour and 45 minutes.

“I feel like it’s just as bad as it was before the construction,” he said, referring to major road construction projects designed to improve the flow of traffic in recent years. He acknowledged that future office development along the corridor will only make it worse. “You see all these empty lots and you know it’s coming.”

Evolution of the ‘Mercer Mess’

Almost everyone who has worked in, lived in or visited the South Lake Union area of Seattle has experienced the slow journey along Mercer Street to Interstate 5. The corridor was a challenge long before Amazon made the neighborhood its home, but the arrival of the tech industry has made Mercer Street a case study in the impact of rapid employment growth on urban infrastructure.

A series of major construction projects have attempted to improve the flow of traffic along Mercer Street. (SDOT Graphic)
A series of major construction projects have attempted to improve the flow of traffic along Mercer Street. (SDOT Graphic; Click for larger image)

The infamous “Mercer Mess” even has its own website, run by KIRO 7, which shows the first known usage of the term in the Seattle Post-Intelligencer in 1966.

Initially, the city built the Mercer corridor as a temporary solution during the construction of I-5. According to the Seattle Department of Transportation, “its circuitous one-way routing slowed traffic, often led to congestion backing up onto I-5 and created conditions that contributed to over 200 accidents that occurred nearby each year.”

Clearly, the intersection faces the same congestion today.

The city now holds the title of “Crane Capital of America,” according to The Seattle Times. Seattle currently has more cranes than New York and San Francisco combined, many in South Lake Union and downtown.

The explosive growth has largely been fueled by a booming tech industry around South Lake Union, driven by the astonishing rise of and its more than 25,000 Seattle area employees. Revitalized streets, countless new restaurants and yes, even a free banana stand gave the neighborhood a new face.

The site of Google’s future campus in the South Lake Union neighborhood. (Vulcan Inc. Graphic; Click to Enlarge.)

And more is coming. Google this year announced a plan to relocate a portion of its Seattle area workforce to 607,000 square feet of new office space (and 812 underground parking spaces) along Mercer Street in 2019. The project created further uncertainty about how the cluttered neighborhood could manage any more commuters. The office could fit up to 4,000 employees, adding to the recent addition of Facebook’s added space for up to 2,000 employees on nearby Dexter Avenue.

Although drivers may fear added congestion, the idea of further developing South Lake Union actually received widespread support.

In 2011, the City of Seattle Department of Planning and Development drafted four zoning plans that provided options to increase height and density in the neighborhood. When it opened up to public comments, the committee received over 200 responses from public agencies, community organizations, and individuals. The contributions were largely positive, applauding the city for growing an area so central and pedestrian-centric.

Two years later, the city council approved South Lake Union Urban Center zone changes to “allow for increased density and greater building heights through an incentive zoning program.” Developers can earn extra square footage by providing affordable housing and contributing to public infrastructure.

Councilmember Rob Johnson (City of Seattle Photo)
Councilmember Rob Johnson (City of Seattle Photo)

Seattle City Councilmember Rob Johnson serves on the zoning and transportation committees, putting him right in the center of the issue.

“We want to make sure that we’re not overly focused on moving cars without recognizing the real importance of moving people,” he said. “We spend a lot of time on how to make the corridor flow better for the existing traffic in the neighborhood, [but] when we do that, we also lose sight of the really important quality of life issues around people getting across Mercer and those smaller neighborhood streets.”

Johnson sees the plan as a way to make South Lake Union a “live, work, play environment,” throughout which he focused on what’s at the heart of the city: people, not cars. While projects and policies aim to reduce traffic, they also seek to provide options that reduce the number of cars on the road altogether.

Microsoft co-founder Paul Allen’s Vulcan Inc. has been the primary developer in the South Lake Union neighborhood, thanks to property holdings dating back to the failed Seattle Commons campaign. Last year, Vulcan gained City Council support and reduced permit fees for one project by pitching a pedestrian-friendly (and car-evading) “woonerf” in the neighborhood. It’s a lighthearted word for a practical concept, but this “living yard” model puts pedestrians before motorists by paving wider walkways and creating a blurred line between street and sidewalk. (Similar to Bell Street downtown.)

But as more employers flock to the area, so do the employees, or more importantly, what they bring with them: cars.

The challenge of ‘induced demand’

Traffic on Seattle's Mercer St at rush hour (Photo by GeekWire/K
Traffic flows on Mercer Street leading to Interstate 5 in Seattle. (GeekWire Photo / Kevin Lisota)

While commuters curse the infrastructure, many wonder why the city can’t simply fix the issue when some of the world’s best and brightest minds are right in this zip code.

In December 2014, the Seattle DOT addressed the issue by expanding Mercer Street to incorporate three lanes in each direction in what it called a “critical widening.” However, research shows that adding more lanes traditionally leads to inviting more cars, resulting in minor improvements—or none at all.

This theory of induced demand ideally drives city planners to solutions that actually reduce the amount of cars, as opposed to making conditions more favorable for them.

According to a 2010 study at UC Irvine, “any policy that reduces congestion without otherwise making driving more expensive [tends to] attract new traffic that at least partially offsets the policy’s effect on congestion.” Once congestion is down, driving gets easier, so there’s less incentive for drivers to seek alternate transportation. More drivers get on the road and congestion returns back to its initial state.

It’s not to say that the city hasn’t been trying. By opening Mercer Street to two-way traffic in 2012 and completing a new SR 99 bridge over Mercer Street in 2014, the Mercer Corridor Project moved along toward a more efficient configuration.

But $74 million of construction (so far) has amounted to reducing commute times by a mere two seconds. Drivers used to spend an average of 7 minutes and 50 seconds on the Mercer corridor, now sitting for 7 minutes and 48 seconds.

What about smarter traffic signals? A representative at the Seattle Department of Transportation shared that “Seattle will be introducing adaptive signal control to help mitigate congestion during peak commute hours” in early 2017.

It comes with a fair warning that while traffic lights can impact flow, they cannot affect the sheer volume of cars on the road.

“[Adaptive signal control] will be less effective during the peak periods, especially the evening peak, when traffic is backed up trying to get onto I-5 and other destinations,” the statement followed. “Even the latest technology cannot move more traffic when there’s no space ahead.”

Commuters in nearby Bellevue, Wash., welcomed adaptive signaling in 2015. Much to their delight, the new system initially reduced traffic time by 36 percent— but a traffic director told The Seattle Times that the traffic simply returned to its original state as time passed.

Unfortunately, there’s little hope that frustration will simply drive people out of their cars. This September, travel analytics company INRIX found that 30,000 more cars use the Mercer corridor now than they did two years ago.

Perhaps the right perspective is this: Mercer Street now manages tens of thousands more vehicles per day with hardly any increased delays.

If it feels like the future of cars is getting dimmer, it’s probably true. On the bright side, life for pedestrians and public transit riders is looking up. Curt Archambault of the South Lake Union Chamber of Commerce believes that the solution involves many components.

“We have limited space,” he said. “We’re not building any new roads.”

Archambault brings up the concept of “multimodal transportation,” which pieces together buses, bikesharing, carsharing, walking — and, yes, personal vehicles — in the most efficient way. A hypothetical employee could take a commuter shuttle to work, use a Zipcar or a Car2go for an afternoon meeting, walk to a restaurant for dinner, and take a Lyft or Uber home. On the day of a doctor appointment or evening plans, they may choose to drive.

“Big employers have to sell the urban lifestyle, which includes how to get around,” said Archambault. “I moved here [to SLU] with a suburban mindset. We had two cars, so we wanted to buy a second parking spot. Then I realized we don’t need two cars. How do you sell that different way of living?”

In 1991, Washington passed the Commute Trip Reduction (CTR) Law, designed to “require major employers and employers at major worksites to implement programs to reduce single-occupant vehicle commuting.” The City of Seattle adopted its own CTR program soon after and reports significant success in its partnership with local employers.

Traffic on Seattle's Mercer St at rush hour (Photo by GeekWire/K
A traffic cop directs cars in at rush hour on Mercer Street. (GeekWire Photo / Kevin Lisota)

Just look at South Lake Union poster child,, which won gold status for its car-reduction commuter programs. In addition to free ORCA cards, the company claims that more than 50 percent of its employees get to work without a car and recently launched its Amazon Ride shuttle service, which even allows dogs.

Even with flawless and free public transportation, some employees simply need the flexibility of a car. Commuters like Nelson have kids, pets, or appointments that often require a direct route in the least amount of time possible.

“I drive to work for the flexibility I need for my lifestyle,” he said. “I have a daughter, so I need to be ready for an emergency.” Case in point, her school once experienced a bomb threat that required parents to pick up students with no advanced notice.

Fortunately for him, he sees an alternative in the future. “When Google moves in, my lifestyle will be changing — my daughter will be old enough to take the bus — so I’m glad I’ll be able to be one car off the road.”

Any way you look at it, the issue comes down to a small amount of land and a massive amount of cars.

SDOT will continue to strive toward a positive experience for drivers, but South Lake Union is moving at its own speed toward a modern, multi-modal neighborhood that encourages a much broader scope of urban mobility.

The recent approval of the Sound Transit 3 plan opens the door to one more option, albeit not until 2035. In the future, commuters will clear Ballard to South Lake Union in under 10 minutes. As a testament to their dedication to improving traffic, a number of influential companies helped the campaign, with Microsoft, Amazon, Expedia, and Bill Gates all contributing $100,000 or more.

Councilmember Johnson chooses to acknowledge the present but focus on the future.

“If we’re successful, it’ll take 15-20 years to build up that infrastructure,” he says, “but it will make a huge difference for the next generation of entrepreneurs that want to continue building businesses in Seattle.”

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