SEA-TAC Pedestrian Walkway

Details

General Contractor: Clark Construction Group
Sector: Transportation
Region: USA
Business: Bridges
Service: Steel Fabrication, Steel Installation
Date: 2020
Location: Seattle, Washington

The SeaTac Pedestrian Walkway is the world’s largest structure over an active taxi-lane, and it took eight years to plan, design, and construct this bridge. This iconic aerial walkway, has a length of 780-feet and height of 85-feet, long enough for two Boeing 747’s to fit under this bridge, wing-tip to wing-tip. The pedestrian bridge connects the satellite terminal to the SeaTac airports new international main terminal (IAF), which was built by Supreme a year prior to the sky-bridge.

The south satellite and concourse A sides of this pedestrian walkway, are made up of large V-pier structures and monolithic cannon base structure. These elements are made up of heavy steel plates (up to 4-inches in thickness), with most of the points being CJP’s on facture critical material. Each V-pier weighs 260,000 pounds or 130 tons, which is more than two blues whales.

Once the V-piers were fully erected and welded out, the taxiway was fully closed and the center-section was moved in place. This center-section was originally shipped from Supreme’s Portland shop is up to 80 foot-sections. Modularly connected off-site into the center-section “super structure” stretching to a total length equal to a football field and weight of 3 million pounds. From the Pre-fabrication area, this center span was transported per a self-propelled modular transport device 3 miles down the airports center runaway to its final destination.

To allow for prior fit-up, the V-pier structures were design to roll-back and raise (like a draw bridge), with large strand jacks mounted on the fare cantilever ends of these structures. Once the center span was positioned in place and risen to proper elevations, the V-piers structures rolled back to lock the center section in place. The installation and weld-out of the center section was successfully done in a 7-day closure of the tax-way.

This structure was designed to adhere to codes per AWS D1.5, D1.1 and DW1.8.

Highlights

The walkway would be only the third such structure of its kind at any airport, and the world’s longest. To put the size of this bridge in perspective, picture a bridge 150ft longer than Seattle’s Space Needle!

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