THE STRENGTHENING OF HAMMERSMITH BRIDGE.

The suspension bridge over the River Thames at Hammersmoth with a main span of 422 ft, was opened in 1887. It carries a 2-lane carriageway and two footways. The chains are of mild steel, the structural towers, suspenders, cross girders and balustrading of wrought iron, and the decking of timber. When failure of some short suspenders, the inadequacy and suspected fatigue of the stiffening girders, seizure of the chain saddle rollers and rotting of the timberwork necessitated the replacement of these items, the restraints of 'listed building' control and maintenance of road and river traffic posed some interesting problems. Temporary 'splint' girders were provided to maintain longitudinal continuity while the stiffening girders were replaced in 24 ft sections, and prefabricated timber panels were used to enable 16 ft lengths of existing deck to be removed and replaced overnight. Temporary gaps in the deck were bridged during the day with portable battledeck units. The 18000 sq ft area of deck was surfaced with a patented gritted epoxy resin and has neoprene filled expansion joints. The chain saddle rollers were replaced by smaller diameter high tensile steel rollers placed between them, the load being transferred to the new rollers by the driving in of shallow wedges with hydraulic jacks. Flexible airtight covers with dessicants now protect the new rollers from dirt and corrosion. /Author/TRRL/