As part of Miami-Dade County’s ongoing infrastructure investment and modernization efforts, the Skytrain system at Miami International Airport (MIA) Terminal D serving American Airlines is undergoing significant structural rehabilitation. The Skytrain plays a critical role in transporting passengers across the Terminal D complex, and the existing substructure began to show signs of concrete damage resulting from Alkali-Silica Reaction (ASR). This chemical reaction compromises the performance of concrete over time, affecting the structural integrity of the Skytrain Piers, prompting the need for targeted restoration efforts. The project focused on mitigating the ASR damage and restoring the durability and performance of the Skytrain’s supporting substructure to ensure long-term operational reliability and public safety. The Miami-Dade Aviation Department (MDAD) closed the SkyTrain services in 2023 due to safety concerns with the condition of the substructure supporting the SkyTrain tracks over Terminal D

KLINE was selected as the Structural Engineer of Record for all the phases of the Skytrain restoration program, leading the structural evaluation, design of repairs, and technical oversight for the rehabilitation of piers and girders impacted by ASR. Our team collaborated with Structural Builders & Restorations (SBR) to develop an effective repair method to mitigate the observed ASR problems.

Project Highlights:

KLINE’s work spans across multiple scopes and project phases, with a focus on ensuring safety, extending structural service life, and minimizing operational disruptions. Our team has provided:

• In-Depth Structural Evaluations: 
  Conducted comprehensive condition assessments on the SkyTrain piers and girders, including field investigations, core sampling, and GPR (Ground Penetrating Radar) scans to assess crack propagation, rebar locations, and material integrity. Specific focus areas included Piers 64, 66, 96, 98, and 106, which were performed in 3 different phases.

• ASR-Specific Restoration Design:       
  Developed multi-phase remediation strategies tailored to each damage level, ranging from full-face concrete removal and replacement with added steel reinforcement to lithium nitrate treatment, CFRP strengthening, and epoxy crack injections. Designs were optimized for compatibility with existing materials and APM system requirements.

• Preventive Terminal D Repairs:     
  Surveyed and mapped 66 remaining pier caps in Terminal D for crack evaluation and ASR treatment. Designed waterproofing details, epoxy injection solutions, and expansion joint remediation to ensure structural durability under operating conditions.

• Construction Administration:        
  Actively engaged during construction to review RFIs, submittals, and coordinate with MDAD, HNTB, and contractors. Provided site visits, as-built drawings, and additional detailing as needed to support field implementation.

From jack-blocking for bridge lifts to restoring over 60+ girders and pier caps across North Terminal and Terminal D, KLINE’s technical leadership ensures structural longevity and operational continuity with minimal disruption to airport operations.

Photography and Renderings: ©SBR
©KLINE