Open House: Ways to accommodate demand and impacts

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Evaluated scenarios vs. forecasted demand.The study team identified a range of scenarios that could accommodate varying levels of projected demand. These scenarios draw on the experience of other regions and how they accommodate service through one or multiple airports. The Los Angeles region, for example, is served by five commercial airports of varying size, and brings lessons learned on factors that influence an airport’s success.

The study team looked at scenarios to meet 50% to 60% of demand, 80% demand, or all of the projected demand.

 

Scenario 1: Baseline, Meet 50% to 60% of demand

The baseline scenario reflects the existing commercial service capacity, as well as plans already in place to expand capacity at Sea-Tac. In the baseline scenario, Sea-Tac would implement a range of near-term and long-term projects to increase aircraft gates from 83 to an estimated 105 to 113, and Paine Field would maintain its current capacity of 24 flights per day with its two gates.

The baseline scenario would result in a gap of 22 to 27 million annual enplanements of unmet demand by 2050.

Port of Seattle - Proposed SAMP Near-Term Projects

Port of Seattle - Long-Term Vision

 

Scenario 2: Meet 80% of demand

This scenario includes Sea-Tac’s near-term and long-term projects, Paine Field would maintain current capacity, and there would be significant development at one or multiple existing airports to accommodate 11 million annual enplanements.

To accommodate 11 million annual enplanements, one airport would need two parallel runways of at least 7,000 feet with a separation of at least 4,300 feet, or two airports would each need a single runway that is at least 7,000 feet long.

Examples of airports with one vs. two runways.

This scenario would result in a gap of 11 million annual enplanements of unmet demand by 2050.

 

Scenario 3: Accommodate 100% of projected gap

This scenario includes Sea-Tac’s near-term and long-term projects, Paine Field would maintain current capacity, and there would be significant development at one or multiple existing airports, totaling three new commercial service runways.

To accommodate demand at one airport, that airport would need three parallel runways, each at least 7,000 feet long. This configuration would be similar to Sea-Tac today.

This scenario could also be achieved using two or three additional airports: one airport with two parallel runways plus one airport with a single runway, or three airports with single runways.

Examples of airports with three runways.

Ways scenarios could be achieved

The study purpose was not to make recommendations about expanding or changing service offerings at specific airports in the region, but to identify airports with technical criteria required to expand in the future. Those criteria were:

  1. Ability to accommodate single or parallel runways
  2. Existing airspace constraints or conflicts
  3. Impact to Sea-Tac aircraft operations (airspace)
  4. Flood zone hazard
  5. Ownership
  6. Current and future roadway and transit access
  7. Incompatible land use within a mile of 7,000-foot or 9,000-foot runway ends
  8. Ability to accommodate additional aircraft operations
  9. Impact to aerospace manufacturing
  10. Population and employment within 60-minute drive time

 

Technical analysis of existing airports

The team rated each airport in the region on its ability to meet the technical criteria.

It’s important to note that this study is identifying airports with technical criteria required to offer commercial service. However, for an airport to begin offering commercial service, it must have a commercial airline interested in expanding to that location. Any change in status from a general aviation airport to a commercial service airport would need to be driven by the market and would also require support from that airport and the FAA.

Criteria 1: All seaplane bases, all state airports, Gray Army Airfield, Auburn Municipal, Renton Municipal, Darrington Municipal, and Swanson were all eliminated due to inability to feasibly accommodate a longer runway or parallel runways. Boeing Field, Norman Grier Field, Pierce County, and Shady Acres were eliminated because they are unable to accommodate commercial service needs. After this initial review, nine airports remained for further study.

Criteria 2 and 3: Apex Airpark, First Air Field, and Vashon Municipal were all eliminated due to existing airspace constraints or conflicts and impacts to existing Sea-Tac airspace operations.

Criteria 4: Harvey Field was eliminated due to flood zone hazards.

Criteria 5: McChord Field was eliminated as an option because it is owned by the military and already busy with military use. 

After the five criteria were applied, four airports remained for more detailed study. These four airports, Arlington Municipal, Bremerton National, Paine Field, and Tacoma Narrows, meet the technical criteria required to add some level of commercial service.

Arlington Municipal Airport

Layout analysis: Arlington Municipal can accommodate a 7,000-foot or 9,000-foot runway but has limited ability to accommodate parallel runways. Adding commercial service would not negatively impact aerospace manufacturing.

Drive-time coverage: Adding commercial service at Arlington Municipal would only increase 60-minute drive-time access for 1% of the region’s population.

Roadway and transit access: Arlington Municipal has interstate and state highway access, and potential for arterial access and high-capacity transit service.

Airspace analysis: Arlington Municipal does not have existing airspace constraints or conflicts, and adding commercial service would not impact Sea-Tac operations.

Bremerton National

Layout analysis: Bremerton National can accommodate a 7,000-foot or 9,000-foot runway and has space for parallel runways. Adding commercial service would not negatively impact aerospace manufacturing.

Drive-time coverage: Adding commercial service at Bremerton National would increase 60-minute drive-time coverage by 14% for population and 12% for employment.

Roadway and transit access: Bremerton National does not have interstate access or ability to connect to an interstate, but it does have state highway access. It has limited ability to develop an arterial to access the airport, and limited ability to add high-capacity transit.

Airspace analysis: Commercial service could be constrained by Sea-Tac traffic over Puget Sound and military operations, although these should be manageable through careful airspace design and modern navigation.

Paine Field

Paine Field already provides commercial service, with up to 600,000 annual enplanements. The airport is starting a Master Plan, which will establish needs for future development.

Layout analysis: Paine Field can accommodate a 7,000-foot or 9,000-foot runway but cannot accommodate widely spaced parallel runways. Expanding commercial service would negatively impact aerospace manufacturing.

Drive-time coverage: Expanding commercial service at Paine Field would not increase 60-minute drive-time coverage.

Roadway and transit access: Paine Field has access to I-5 via SR 526, has potential to develop an arterial to access the airport, and has the ability to add high-capacity transit access.

Airspace analysis: Paine Field does not have existing airspace constraints or conflicts, and expanding commercial service would not impact Sea-Tac operations.

Tacoma Narrows

Layout analysis: Tacoma Narrows can accommodate a 7,000-foot or 9,000-foot runway and has moderate ability to support parallel runways. Adding commercial service would not negatively impact aerospace manufacturing.

Drive-time coverage: Adding commercial service at Tacoma Narrows would increase 60-minute drive-time access to a commercial service airport by 22% for population and 15% for employment.

Roadway and transit access: Tacoma Narrows does not have access to an interstate, but SR 16 serves the function of an interstate. It has limited potential to add arterial access, but could add high-capacity transit service.

Airspace analysis: Tacoma Narrows’ airspace has conflicts from Sea-Tac, Boeing Field, and military traffic, and it would moderately constrain Sea-Tac air traffic. Modern navigation technology may be able to minimize these conflicts in the future.

Should demand be met?

The aviation industry provides economic benefits to the region, but expanding aviation service to meet demand also comes with environmental impacts. The aviation industry is moving rapidly to address these impacts through navigation systems that will increase airspace efficiency, better fuel economy, use of electric aircraft, and quieter engines. While we don’t have the information to quantify how these systems will improve over the next 30 years, we do know that the environmental impact of aviation in 2050 will be different than it is today.

While the economic impact of the aviation industry can be more readily quantified than shifting environmental impacts, we understand that the environmental impacts – including noise impacts – are no less real.

As of 2019, WSDOT’s Airport Economic Impact Study estimated that Sea-Tac contributed 151,400 jobs, $7 billion in labor income, and $22 billion in business revenue to the regional economy. The Puget Sound Clean Air Agency Greenhouse Gas Emissions Inventory estimated that 654,600 metric tons of GHG were emitted in the region as a result of air travel in 2015. This amount reflects approximately 2% of total regional emissions and 5% of regional transportation emissions.

 

This study was not intended to advocate for meeting all projected future demand, but to identify that demand so that legislators and other decision-makers can plan for growth. Key questions and issues for further study will be the cost versus benefits of consolidating impacts at one airport or spreading impacts across multiple airports, and if a meaningful level of service would be offered should commercial service be dispersed across multiple single- or two-runway airports.

 

Next: Next steps