Bridges and Tunnels Jenny Spratt Bridges and Tunnels Jenny Spratt

Gasometer Bridge

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Project description

 

On behalf of the City of Schlieren, Stahlton carried out a GPR survey of the post-tensioned Gasometer Bridge. Using the Proceq GS9000, the team mapped the concrete cover and the layout of the tendons across the deck. Based on these results, a targeted inspection opening was positioned at the tendon, where the condition of the duct and grout was verified visually. All data was documented in INSPECT, giving the project engineer a clear basis for planning the next steps – with a minimum of openings.


AQUILA’s contribution

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The Gasometer Street Bridge in Schlieren, Switzerland is a four-span post-tensioned road bridge from 1988 over the SBB railway tracks near Zurich, and its owner needed a reliable basis for its repair planning and 2027 budget, with a focus on the prestressing.

 

Our process

Stahlton team scanning the bridge deck with a Proceq GS9000 ground-penetrating radar, requiring only single-lane closures for scanning of carriageway.

Drone technology was used to do local GPR scanning on the underside of the bridge superstructure in advance of coring, and then to conduct the actual coring.

Targeted inspection opening at one tendon showing the condition of the post-tensioning system and grouting at that location.

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Bridges and Tunnels Jenny Spratt Bridges and Tunnels Jenny Spratt

Bridge B-235

excerpt text here


Project description

 

For the Canton of Aargau, Stahlton assessed the condition of the post-tensioning in Bridge B-235. The inspection was carried out in two phases in 2025, one per traffic direction. Tendon layouts were mapped with GPR, and ultrasonic pulse-echo measurements identified potential grouting defects. Selected locations were verified through inspection openings and anchorage checks, complemented by a visual inspection. All findings were consolidated in INSPECT, providing the canton and the structural engineer with a reliable basis for maintenance decisions.


AQUILA’s contribution

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Aerial view of Bridge B-235 during the inspection campaign with half-side lane closure.

 

Our process

GPR mapping of post-tensioning ducts and reinforcement using the Proceq GS9000.

Ultrasonic pulse-echo measurement with the Pundit PD8050 to detect grouting defects.

Inspection opening showing the condition of the duct and grout.

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