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Roadway Improvements

Status: In progress

Project Overview

This project is a roadway improvement project aimed to help alleviate the crowding and congestion outside of the airport, update systems, and make updates to support the ever-changing environment and dynamic region. The original roadway was designed in 1968 to support an average of about 25 million passengers annually. In 2019, SEA averaged around 51.8 million passengers causing significant congestions and queuing daily during peak times. Based on studies done, it is estimated that without any improvements, the airport traffic will reach the I-5/I-405 interchange. 

While several efforts have been completed over the years to extend the life of the current roadway system, the increase in passengers through SEA has required a higher demand. Past projects have included relocating commercial ground transportation services to the third floor Ground Transportation Center and Northeast Ground Transportation Lot, extending the Arrivals curbside to the south for public transit and commercial ground transportation, and relocating rental car customers off-site to the consolidated Rental Car Facility. 

The Roadway Improvements project will widen the southbound lanes of the Northern Airport Expressway to provide an additional two lanes, taking it from four lanes to six lanes, from S. 170th Street into the Departures and Arrivals curbside and Main Garage. The widening of roadways that access the Arrivals drive and the Main Garage will help improve access to parking, ground transportation center, and curbsides. The goal is to alleviate congestion and reduce queuing on the main roadway entrances for airport visitors and passengers and enhance roadway safety. 

The major construction for this project is being designed in two main parts. The first contract will include the early work which involves the demolition of the fourth-floor bridge between Departures and the Main Garage. The second contract includes the roadway realignment, lane additions, and utility system infrastructure improvements. In addition, the project will also relocate the north rental car bus curb farther north and relocate and renew utility infrastructure impacted by this project.

Map of Widen Arrivals Roadway map

Early Work - Roadway Ramp Demolition

Construction took place in September of 2022, to remove an unused roadway ramp on the Arrivals Drive as part of the early work for the greater Roadway Improvements Project. The demolition took place in three different phases in order to safely remove the ramp while working overnight hours in order to lessen the traffic impact to visitors.

 Recap of the roadway ramp demolition:

  • The first phase took place the week of Sept. 12, 2022, with the demolition of the ramp's southern span
  • The second phase began the week of Sept. 19, 2022, and involved the demolition of the northern span
  • The third and final phase of this construction began the week of Sept. 26, 2022, and removed the center span of the ramp. It had the most impacts and required a full closure of the Lower Arrivals Drive.

Center span of ramp awaiting to be demolished

Bridge demolition

There was some other minor early work that took place to replace some of the concrete barriers along the drives. Construction for the widening of roadways will kick off late summer 2023.

Community Benefits

The contract has a Small Business Enterprise (SBE) goal of 20 percent.

This project will support multiple objectives in the Century Agenda by improving access and decreasing congestion entering the airport. A byproduct of reduced congestion is a decrease in emissions from vehicles in traffic.


Early work Construction begins Q3 2022 Construction to be completed by Q4 2022
Main work Construction begins Q3 2023 Construction to be completed by Q1 2026

Estimated Project Costs

Total estimated project cost: $79.3 million

Funding for the project will come from a combination of Airport Development Fund, Future Revenue Bonds, and a Federal Aviation Administration Grant. As with virtually all airport projects, no tax-payer dollars will be used to fund the project.

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