Phase 3 Post Tensioned Special Investigation


Built in 1951 to a design prepared by Mouchel, Castle Walk Footbridge, was the first prestressed concrete counter balanced cantilever footbridge to be built in the country.

HTS, the UKAS accredited testing division of Topbond plc, has extensive experience of undertaking Post Tensioned Special Inspection (PTSI) of structures throughout the country, and were appointed to undertake the Phase 3 inspection of this structure.

The inspection points were located at key positions across the bridge, including in the main span over the River Severn.  To permit rapid access to the main span a flexible manoeuvrable access platform was provided from Topbond’s fleet of marine plant.  Owing to the fast-flowing nature of the river and the position of the bridge upstream of a weir a safety boat was in attendance during the works.

The site works included concrete condition testing for depth of cover and half-cell potential as well as sampling for chlorides and carbonation testing.  As part of the works the post tension ducts were intrusively inspected.  Ground probing radar equipment was used to locate some ducts and a video endoscope survey of the half joint was carried out.