Installing the world’s longest elevated pedestrian bridge over an active airport taxi lane was relatively straightforward thanks to a digital solution, explains Marion Bouillin of Bentley Systems.

The Port of Seattle has big plans for Seattle–Tacoma International Airport, more commonly known as Sea-Tac. To add to the international passenger experience and promote the Puget Sound region as a leading tourism and business gateway, the Port is building a new, expanded, 450,000ft2 International Arrivals Facility (IAF) at the Washington State hub.

The project includes constructing a 345,000ft2, three-storey grand hall, a new connecting international corridor, and an 85ft-high pedestrian aerial walkway connecting the new grand arrivals hall with the airport’s South Satellite. Clark Construction was hired as the design-build contractor for the $968m project, the most complex capital development programme in the 71-year-old airport’s history.  

Delivering an iconic aerial walkway  
Clark faced several challenges delivering the new facility, the most difficult being the remote assembly, transport, and installation of the 3-million-pound, 320ft-long centre span for the world’s longest pedestrian walkway over an active airport taxi lane.

To optimise safety and minimise impact to ongoing airport operations, the team needed to fabricate the bridge span at a nearby cargo area and then transport it along a three-mile route across the airport’s centre runway to the installation spot.

Overcoming these challenges and meeting the airport owner’s request for a digital, data-rich model deliverable required careful planning, demanding interoperable BIM (building information modelling), reality modelling, and construction scheduling and simulation technology. 

The bridge being positioned
Bentley’s application enabled the precise planning and successful fit of the iconic walkway within three-eighths of an inch

Leveraging 4D construction 
Clark opted for the SYNCHRO 4D virtual construction platform from Pennsylvania-headquartered construction software specialist Bentley. “SYNCHRO 4D, in conjunction with industry expert knowledge and leading construction technologies, helped us digitally plan the successful remote assembly, transport, and install of the world’s longest pedestrian walkway over an active airport taxi lane,” explained Brian Krause, vice president, Clark Construction Group.  

With no room for error, Clark leveraged cutting-edge survey and modelling technology with SYNCHRO 4D application to visualise and analyse the existing site and the bridge from early in the conceptual and schematic design stage, right through to construction.

This workflow helped Clark understand every detail and determine how to construct the aerial walkway, efficiently and safely. The team modelled the prefabricated bridge span and pier supports, linking the 3D model with the construction schedule to develop a digital twin and fully visualise the construction sequence. Using SYNCHRO 4D facilitated construction simulation and animation to support the planning, communication, and execution of the prefabricated, massive centre bridge span in the middle of the busy airport. 

Digitalisation achieves world record
SYNCHRO 4D helped the IAF team construct and build the world’s longest elevated pedestrian walkway over an active airport taxi lane with confidence. Throughout the bridge planning and execution process with SYNCHRO, the team generated detailed laser scanned point clouds and meshes and performed measurements and deviations, confirming the accuracy of the bridge design and installation on site through the development of a digital twin. Bentley’s application enabled the precise planning and successful fit of the iconic walkway within three-eighths of an inch, without causing any airport disruption. The digital twin deliverable will be used by the Port of Seattle for ongoing facilities management.