Edinburgh Airport Multi-Storey Car Park

Structural Investigation and Post-Tensioning Special Investigation

Interspan has completed a comprehensive structural investigation of Edinburgh Airport’s Terminal Multi-Storey Car Park, providing detailed information to support the ongoing management of this important airport asset.

Constructed in 2004, the five-storey post-tensioned concrete car park comprises 150mm post-tensioned slabs spanning approximately 7.5m onto 525mm-deep post-tensioned band beams, which span approximately 15.6m between reinforced-concrete columns.

Now approaching the middle of its design life, the highly utilised structure required a detailed assessment to establish its current condition and to provide an evidence base for future monitoring, maintenance and asset management decisions.

Project Overview

Location: Edinburgh, UK
Asset Owner: Edinburgh Airport
Contractor: Scott Signs
Consulting Engineer: Tony Gee and Partners
Structure: Post-tensioned slabs and beams with reinforced concrete columns
Scope: Structural investigation and Post-Tensioning Special Investigation (PTSI)

An Investigation-Led Approach

Interspan was appointed to undertake a comprehensive investigation combining non-destructive testing, targeted intrusive investigation and specialist Post-Tensioning Special Investigation techniques.

The investigation included:

• Close visual inspection, crack mapping and delamination surveys to slabs, beams, columns and waterproofing membrane
• Ground Penetrating Radar (GPR) to establish reinforcement and tendon locations and verify the existing construction
• Half-cell potential surveys to assess the probability of reinforcement corrosion
• Ultrasonic Pulse Echo (UPE) surveys to identify anomalies, concrete voids and potential defects associated with grouting of the PT ducts
• Chloride and carbonation testing
• Targeted reinforcement breakouts
• Specialist Duct Tendon Exposures (DTEs) to inspect PT ducts, grout and prestressing strands
• Sampling and laboratory analysis of concrete and PT grout
• Assessment and recording of reinforcement and prestressing steel condition

The PTSI was undertaken to establish the condition of the post-tensioning system at critical locations, assess deterioration and corrosion risk and provide information for the structural appraisal. The investigation was carried out in accordance with Design Manual for Roads and Bridges CS 465.

Using NDT to Target Intrusive Investigation

A key element of Interspan’s methodology was the use of non-destructive testing to inform and target subsequent intrusive investigation.

GPR was used to verify tendon and reinforcement arrangements, particularly where existing as-built information was incomplete. UPE was then used to identify potential anomalies associated with the post-tensioning system.

This allowed targeted opening-up to concentrate on locations where further physical investigation would provide the greatest value, enabling the project team to establish actual conditions, obtain material samples and develop a more informed understanding of the structure.

Working Within a Live Airport Environment

All investigation works were undertaken within an operational airport car park.

Careful segregation, traffic management and daily coordination were required to minimise disruption to airport operations and members of the public. The works were also programmed around operational requirements, including a break over the Easter holiday period so the car park could remain fully available during a particularly busy period.

More Than 1,350 Investigation Locations Digitally Recorded

Interspan recorded the investigation using a cloud-based digital twin, providing Edinburgh Airport and Tony Gee and Partners with live access to information as it was collected.

More than 1,350 individual investigation locations were digitally recorded, allowing photographs, test results and condition classifications to be reviewed against their precise position within the structure.

This provided a detailed and accessible record of the investigation and an evidence base for ongoing structural assessment and asset management.

Supporting Long-Term Asset Management

By combining specialist knowledge of post-tensioned structures with non-destructive testing, intrusive investigation, materials testing and digital data capture, Interspan provided the project team with a detailed understanding of the condition of both reinforced and post-tensioned elements.

The investigation provides Edinburgh Airport and its consulting engineer with the information required to assess deterioration mechanisms and corrosion risk, and to develop an informed strategy for future monitoring, repair, and long-term management of the structure.

Interspan > Investigate. Diagnose. Design. Strengthen. Protect. Extend Service Life.