Hidden Critical Element Inspection and Repair

Client: Amco Giffen Rail

FJD Consulting working on behalf of Amco Giffen Rail split the scheme into two phases in order to manage the logistics of the site inspections. Phase One contained 34 stations and was completed within 7 weeks, Phase Two contained 27 stations and was completed within 6 weeks.

Development of the scope saw more rigorous inspections at 28 locations added to the brief. Two of which were Cardiff Queen Street Station and Chester Station.

Cardiff Queen Street Station’s original remit from Network Rail included the excavation and inspection of six vertical and two horizontal hidden critical elements within the canopies located over Platform 1-2 and Platform 3. Due to the busy nature of the station, the inspection was carried out during the evening.

After uncovering a severe defect on one column which required an Emergency Repair Response, and defects requiring Urgent Repair on a further four columns, it was recommended that further columns were exposed and inspected. Network Rail then ordered that all columns were to be inspected. Following the inspection of all columns a total of two columns required Emergency Repair and 10 required Urgent Repair with all remaining columns requiring Non-Urgent Repair.

Chester Station is a Grade II* listed building and the original remit from Network Rail included for the excavation and inspection of four ‘I’ section columns only located on Platform 3. Following the discovery of a severe defect which required an Emergency Repair, it was recommended that an additional 5 columns were exposed and inspected. In total, six columns inspected exhibited complete loss of section to the web and required emergency propping and repair. Given the extensive severe defects, FJD Consulting recommended that a global canopy stability analysis was undertaken. This was instructed following presentation of the risk to Network Rail and the Contractor.