BGR HOLLOWAY’s scientific contributions

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/

The impounded level of dock is maintained by two sets of gates in the 130 ft wide, 60 ft deep entrance passage leading from the existing dock system. Stop logs permit the dewatering of each gate in its recess for maintenance. The secondary gate is a single side-hung caisson and incorporates a new design of hinge to facilitate unstepping and removal for use in check caisson operations at other locations. Both gates are rope driven from electro-hydraulic systems, the guard gate employing a novel swinging jib device to assist the closing movement. Normal remote control of the gates from a single desk is supplemented by local manual control facilities for emergency use.