Hidden defect: Settlement

Problem: Weetwood Bridge was suffering from leaning side walls.

Solution: The method to halt and arrest the movement involved excavation of fill from between walls and above the arch barrels; this was replaced with polystyrene fill and transverse ties were fitted. JF Strainstall provided a movement and settlement monitoring system to measure any heave resulting from the removal of significant dead load.

Hidden defect: Scour

Problem: The bridge is located across an upland river which is subject to flash flooding and fast flowing water. Scour of the bridge foundations was a concern.

Solution: The risk of scour undermining the foundations had been mitigated by the construction of a concrete apron to channel the water away from the structure. However, this was being undermined by scouring action, indicating that there remained a risk of bridge foundation scour occurring. Sensors were installed in conjunction with a solar powered data logger to monitor inclination of the concrete apron and to provide a real time alert of possible scouring.