Mr A. C. G. Hayward (F) (Cass Hayward & Partners)
The author’s interesting experiences in Papua New Guinea must be typical of those in other Far East countries where flooding and earthquakes occur, and I can echo similar conditions in Indonesia. Throughout history, bridge failures tend to occur by flood action, ship collision, earthquake or vehicle impact. Two of these are natural hazards, the others manmade which are the most frequent failure causes in more ‘stable’ environments. Only rarely does collapse occur from design overload which is the area on which most bridge designers spend their resources. There is a lesson here in that more attention is warranted in design to hazards such as vehicle impact and to the important matter of replacement, should this ever be necessary. Currently, this is a topical matter in the replacement of our bridges for motorway widening, where unit construction bridging may well have an increasing use and many existing bridges are of monolithic concrete construction, making their removal difficult.