A Case Study: Geotechnical Instrumentation for Automated People Mover Tunnel at the World's Busiest Airport

Hartsfield Jackson Atlanta International Airport (H-JAIA) added a $1.4 billion new International Terminal, namely Maynard Holbrook Jackson International Terminal (MHJIT). During this project, the existing Automated People Mover (APM) tunnels were extended from west of Concourse E to MHJIT. The type of excavation was open cut, approximately 70 feet wide and 50 feet deep. The excavation was supported by micro piles, soldier pile/timber lagging system and tie back systems and underpinning piers to a depth of approximately 50 feet below the existing grades. Movement and settlement of the existing test track tunnel and Concourse E was a concern due to unbalanced earth loads and existing foundations for Concourse E. Approximate length of new APM tunnel underneath Concourse E was 1200 feet and underneath Taxiway Dixie was 900 feet. To monitor the settlement and movement, Automated Total Stations (AMTS), Uni-axial and Bi-axial inclinometers were installed. Data generated by the monitoring systems were captured real time and used to provide early warnings and unexpected behavior of the structures associated with the new construction. The risk management program includes alarms generated from the system thru email when measurements exceeded the threshold limits and triggered a plan of action to avert any potential disaster.