Bridge Strengthening and Bridge Renovation

Safespan® has been used extensively for bridge repair, bridge strengthening and bridge renovation. Safespan is only one tenth (1/10) the weight of traditional bridge scaffolding and was originally invented for bridge painting and maintenance.

Vertical cable hangers are installed along each cable at predetermined centres attached via clamps to the bottom flanges of the cross girders and cantilevers. Between each vertical hanger the longitudinal cable forms a catenary. This supports profiled steel deck sheeting which spans transversely between longitudinal cables.

The vertical cables are attached to the longitudinal cables via steel clips. These clips perform several functions:

• A U-bolt on the underside of the clip clamps the longitudinal cable.

• An eye on the top of the clip accommodates a hook at the bottom end of the vertical hangers.

• The clip plates clamp the deck sheeting and provide an effective seal at each connection position.

The transverse deck sheets are overlapped by 300mm to provide additional rigidity and form an effective seal. Prefabricated slots in the sheets allow for connection via the clips.

At the edge of each platform a longitudinal RSA is bolted to the deck sheeting. This acts as a toe board and can accommodate edge protection appropriate to each location. The vertical encapsulation is attached at the base to the toe board. In the troughs of the deck sheeting rubber inserts are installed beneath the toe board to form a complete seal.

Transverse cable positioners (RHS) are provided at several intervals along the structure which change direction at the cables. The positioners are anchored vertically and transversely to the viaduct. A series of straight lengths of longitudinal cable and therefore, platform are then provided which accommodate the horizontal profile of the viaduct.

The deck sheeting and all elements above the sheeting will be inspected from the platform. The longitudinal cables, including connections and the underside of the deck will be inspected from ground level using binoculars. Periodically, an arms length inspection of these elements will be carried out from the mechanical hoists.

The inspection will be carried out by trained personnel who will follow a detailed checklist.

The system has sufficient redundancy and has been designed to accommodate maintenance including replacement of any element of the system.

The platform may be designed for a safe working live load of 2.5kN/m2 with up to 5% of the total area, in local areas to be designated, able to accommodate 5kN/m2.