Earlier this month, the Port of Seattle Commission was briefed on an update of the Sustainable Airport Master Plan (SAMP) for Sea-Tac International Airport. It was the first briefing on the subject in a year and a half. A lot has changed in the direction of the plan, according to project managers. The project was originally scoped to look at 20 years worth of actions; the slow progress has shortened that window to 16 years. The new scope of the plan, however, takes a closer at near-term actions so that they can begin the planning process and break ground successively.

In a memorandum to the Port of Seattle Commission, airport staff explain why the process has experienced such significant delay. “There are two primary factors which have contributed to schedule delay and the increased cost of analysis, documentation, project management, and other soft costs of the SAMP,” the memorandum states. “One factor is extensive airside modeling and coordination with the [Federal Aviation Administration (FAA)] experts to test the ability of development alternatives to meet near-term and long-term demand and to determine a two-step approach to advance SAMP. The other primary factor is additional analysis and documentation required due to the identification of alternatives involving one [versus] two terminals–i.e. accommodating forecast demand within the existing terminal with significant redevelopment/expansion versus accommodating future demand with a combination of a second terminal and less expansion/modification of the existing terminal.”

During the presentation, airport planners talked about an “unconstrained” growth scenario to 2034 where demand for airport would grow to 66 million annual passengers; nearly 47 million passengers passed through the airport last year. Demand for air cargo services would also grow over that time horizon. The number is important because the airport would ideally meet the demand. “Unconstrained” in this context means if the Port of Seattle had unlimited resources to fully implement all projects necessary to meet the demand. It’s not clear, at this point, if the airport does given site and funding constraints.

The full suite of projects that would be needed through 2034 to meet demand. (Port of Seattle)
The full suite of projects that would be needed through 2034 to meet demand. (Port of Seattle)

Arriving at the “unconstrained” growth number is fairly complex and involves multiple sources. The include a model from the Federal Aviation Administration (FAA) that can be checked against for consistency. Other data points come from forecasts by the airlines and local growth projections from the Puget Sound Regional Council (e.g., demographics, per capita spending habits, and population growth). Another key factor, aside from landside and airfield facilities, that can constrain capacity is airspace. Increasing demand for limited airspace could pose a challenge in future years. However, the FAA continues to work on programs such as NextGen to improve predictability, efficiency, and capacity.

Looking at a shorter timeframe and less demand, planners have identified several key projects that can head off massive delays to airport operations for the projected 56 million passengers in 2027. The projects largely incorporate existing capacity investments, such as the International Arrivals Facility, expansion of the North Satellite, and building the new Concourse D Holdroom and hardstand facilities. Other projects will be necessary to realize a new terminal entirely. The planned location for such a facility with 19 gates would be north of Concourse D.

To ready the new north terminal, planners have prioritized companion projects that must be completed to allow for a new terminal to be operational. Those priorities include:

  • Relocating the airport expressway further east and making targeted improvements;
  • Relocating several support facilities north of the North Satellite;
  • Taxiway and runway improvements;
  • Building a busway systems from the Central Terminal to the north terminal and rental car facility; and
  • Building new hardstand areas.

The north terminal would be designed that future expansion further north would be feasible, which ultimately could end up in a “U” shape. Landside services, such as baggage, check-in, and parking, are expected to be provided on the east side of the expressway. The main challenge with the north terminal is room to create comfortable corridors, waiting areas, and retail options.

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Planners noted that there had been discussions of a people mover between the Central Terminal and north terminal as well as a new light rail stop to directly serve the north terminal. Both proposal appear to have withered away. It wasn’t clear at the briefing why a people mover was taken off the table. However, planners said that Sound Transit found the idea of adding an infill station in the middle of the expressway to serve the north terminal challenging.

The plan still considers improvements that will likely need to be made through 2034. In the later years of the plan, cargo areas north of the terminal will need to be improved and in some cases moved to an area south of the airport, further expanding the north terminal, and taxiways near the runways will need substantial expansions. The plan anticipates adding a new expressway south of the airport, too.

The project is on course to enter environmental review soon under the guidance of the FAA, the lead agency under the National Environmental Policy Act (NEPA) process. Planners will also conduct environmental review under the State Environmental Policy Act (SEPA) essentially in parallel. A range of topics will be considered as input is provided through scoping such as air and water quality, construction impacts, hazardous materials, archeological resources, and energy sustainability. Airport planners said that while they cannot “predetermine” how the environmental review process will progress, it is likely that the FAA will only require an Environmental Assessment under NEPA which is similar to the state’s Environmental Impact Statement (EIS) process, but significantly less than the federal NEPA EIS process.

To continue with the planning process, airport planners will need authorization for more funding, approximately $800,000. The consultant will finalize the planning documents to start the environmental review process.

Sea-Tac Airport Sustainable Airport Master Plan Update

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Stephen is an urban planner with a passion for sustainable, livable, and diverse cities. He is especially interested in how policies, regulations, and programs can promote positive outcomes for communities. Stephen lives in Kenmore and primarily covers land use and transportation issues for The Urbanist.

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Stephen Fesler

Another presentation on the SAMP happened yesterday. Here’s the PowerPoint: https://meetings.portseattle.org/portmeetings/attachments/2018/2018_02_27_SM_8a_supp.pdf

Al Dimond

Using the word “sustainable” in discussing air travel expansion is one of the worst abuses of the term I’ve ever heard. There’s nothing sustainable about air travel expansion — air travel is utterly reliant on fossil fuels, with less potential for getting off them than any human activity I’m aware of.

As in many highway expansion proposals, we’re asking how we can meet “the demand”, using some blue-sky notion of demand, without asking the question of whether doing so is what we should be doing. Let’s start with that question. Why should we decide, as a city, as a civilization, to increase air travel, knowing its impacts?

Stephen Fesler

The level of emissions from air travel is staggering and must be seriously addressed. I’m aware of a various efforts to use alternative fuels, even electricity for air transport. That doesn’t solve the problem of today, however. There isn’t anything sustainable about air transport.

Sea-Tac has invested heavily in reducing landside emissions. In fact, nearly half of all emissions are born by those travelling to and from the airport by land, not by air, which is something the airport has only modest control over. There are solutions with transit, tolling, and parking fees that could push those numbers further down. For planes, the airport is making efforts to dealing with emissions at gates and other environmental practices.

You also elude to a point of induced demand. I would presume the principle of induced demand partially holds true for air travel. But keeping capacity down also runs the risk of forcing much higher prices reducing opportunity to longer-distance travel to lower-income individuals.

In the long run, it seems highly likely that air transport will have little or no emissions. Air travel will continue to be integral. I don’t think it’s fair to liken it to investing in highways that engender lower quality built environments regardless of whether a switch to electric vehicles is made or not.

Al Dimond

How long a run we talkin’ here? In ground transport (both on the rails and the roads) various types of electric vehicles are available commercially, and yet we still aren’t close to the point where we can expand highways without significantly increasing carbon emissions, even a generation out (considering the long life span of today’s vehicles)! No similar prospects for aviation are close to commercially available. The question of who gets to fly is the same as the question of who gets to drive when roads and fuel are taxed, and the best answer is to work for greater economic equality generally. But we’re way overbudget on pollution, today and generations into the future, and we have to cut pollution on all fronts.

Air travel can’t easily get away with claiming no impact the quality of cities. Noise and point-pollution impacts from airports are enormous. Even if the footprint of SeaTac and its no-build area isn’t going to expand, it’s worth remembering that the noise impacts on existing inhabited neighborhoods are just as bad as being right next to a freeway interchange. Just as I-5 permanently ended the prospect of a quiet day at (to use an example I experience regularly) NE 40th/4th, air travel has ended the prospect of a quiet day in a variety of neighborhoods. An increase in airport capacity will certainly increase noise impacts relative to the no-build alternative!

Stephen Fesler

It’s incredibly socially regressive to restrain people from access to places far away. High-speed rail and other public transport options can supplant some of the demand of long-distance travel, but trying to limit real-world demand for access to opportunity just smacks of eliteism, despite serious environmental consequences of air travel today.

Regardless, obviously environmental implications are more than just air and water quality. Environmental justice, such as noise pollution that you note, should be a critical consideration. We even shared this article recently about the issue: https://www.citylab.com/transportation/2018/02/faa-reauthorization-congress-noise-pollution/552983/

I would note that some perspective is worth considering. Air travel is half as noisy than the 1970s due to efficiency improvements, flight techniques, and technological changes. The increase of air traffic has offset some of that, but the skies are generally quiter than several decades ago. Continuing to address quiet skies is critically important and implementing environmental justice practices should happen as part of the planning process—and even outside of it.

Al Dimond

It can be socially regressive to limit overall consumption of almost anything! Of course when we try to reduce traffic and gas-burning it’s the wealthiest people that are most able to adjust their lives around the new situations. But it’s still necessary. So we focus on economic equality and housing affordability instead of freeway expansion — not that we’re doing very well at it right now (we’re doing flat-out terrible on all three counts, becoming more unequal, with more expensive housing, while planning the cartoonishly awful 509 extension and using 405 tolling and BRT projects as an excuse to expand that freeway and its interchanges)! But it’s always the case that working for economic equality generally is more fruitful than fretting about collective reduction, or here just lack of growth, in one particularly harmful activity, because if people have the resources we have to assume they’ll know how best to apply them to improve their lives. If we view airport expansion through the lens of economic equality, it could hardly be anything but a terribly inefficient way to achieve that!

Al Dimond

But, hey, this is a flying town. On top of all the Boeing stuff here, considering our distance from other major cities, we probably rely on air travel as much as any city out there for our position among national and global cities. Questioning the sustainability of air-travel growth will naturally get me attacked left and right (pun intended). That’s sort of the nature of it: growth-is-good is a big part of the centrist consensus that holds Seattle politics together. I seriously doubt local “airport revolt” movements will take root like “freeway revolt” movements did in some cities. Each city can be so easily measured against its worldwide peers for ease and cost of air travel that it would be hard to limit it any way except globally, together.

The big picture is carbon right now. So if we assume that we’re going to reduce our carbon footprint as in, say, the Paris accords (and if we’re at all honest with ourselves rich American cities need to go much farther than that), where is the carbon budget for increasing air travel? In that environment, does it make sense to plan for increased air travel?


The noise impacts of air travel extend surprisingly far from the airport, itself. Even as far north as Capitol Hill (depending on which way the wind is blowing), planes rumble overhead as often as every two minutes, every day, all day long (and much of the night, too). Beacon Hill is worse. And any expansion of the airport is only going to make it worse, city-wide.

While it is easy to say that the port should just “address quiet skies”, the reality is that we already at the limit of what can be done with current technology. At best, a few 747’s might get replaced by the slightly-quieter 787, but that’s a tiny percentage of the overall number of daily flights. Unfortunately, the SeaTac runways are perfectly aligned so that a straight approach to the runway requires flying directly over Beacon Hill and Capitol Hill, so there’s little chance of reducing noise by altering flight paths, either.

What will inevitably happen, is that the airport will move forward with their expansion, give lip service to some “study” about measuring noise impacts and suggesting ways to improve it. This will be enough to placate the opposition until people forget. And no real, actionable results will ever come out of the “study”.


Indeed. In the Suzz library reading room, you know the one that looks like hogwarts, I’ve been noticing room rattling airplane noise. I’ll try to record it next time.


A perfect example of the kind of leftist garbage we have to deal with in this area. How do you propose the world economy moves and people go from place to place over long distances? Are you going to sprout wings and fly? These people are the single largest group of luddites that I have seen. They worship the planet in place of worshipping God. And everyone around them suffers.


Bummed that the people mover is cut. I was hoping they’d have it serve the main terminal/Link, new terminal, rental car garage, and also Tukwila Link. I hope they reserve ROW for it, but I fear they won’t!