Llanrhystud Bridge Monitoring Works
Installation underside of Llanrhystud bridge in two hours
Key project information
Client: North & Mid Wales Trunk Road Agent (NMWTRA)
Location: Llanrhystud, Wales - A487 / Afon Wyre River
Bridge Constructed: Originally 1962 – Extended 1994
Type of Structure: Post tension slab (1.2m deck depth)
Main Concerns: No records to assess structure
Number of Detectors: Four (XL type)
Scan duration: 16 days
Customer objectives
Muon Tomography will be carried out to establish construction information.
Items of particular interest are the location and dimensions of reinforcement and PT apparatus.
The locations determined will be used to identify locations for intrusive inspections of PT apparatus.
In addition to the minimum requirements set out in the technical plan, efforts have also been made to provide further information (to better demonstrate the capabilities of muon tomography), including:
Estimates of cross-sectional areas of pre-stressing steel within the PT ducts
Estimates of bar diameter for the reinforcing steel
Detection of defects including:
Voids within the concrete
Partially grouted tendon ducts
Wire/ strand breaks within the PT tendons
The challenge
Access: River levels make underside installation not possible November to March.
Traffic: Main trunk road serving West coast.
Accuracy: Precise geometry to be mapped to facilitate coring to visually confirm tendon.
Our approach and solution
Deployment: 2x pairs of detectors were distributed to capture the client’s identified key areas. Simple temporary traffic light set up with one lane closure.
Scanning: Once installed & commissioned, units left unmanned for full 16 days scanning period.
Analysis: Transitioning raw data into actionable insights for the client when each stage became available.
Results & Impact
Safety Assurance: Confirmed integrity and structural geometry within the areas scanned which was unknown.
Dimensions: After calibration sizes of reinforcement & tendons were recorded
Defects: Identified area of further investigation on precise location of a tendon.
Efficiency: Completed all scans within the allocated timeframe without extending traffic closures. Bridge remained open even during mobilisation & demobilisation.
Future-Proofing: Established a data baseline for yearly structural asset health monitoring and effectively extending service life.
“We are very happy with the results GScan have provided; the MFT successfully located all the PT apparatus and steel reinforcement of the area scanned. We are now in a much better position to manage the structure.” - Bob Humphreys Principal Engineer at YGC
GScan Ltd | The Bradfield Centre | 184 Cambridge Science Park, Milton Road | Cambridgeshire, CB4 0GA | UK
Contacts: graham.kneller@gscan.eu, +44 7957 658237