Hand-dug Caisson excavation in Hong Kong – worst recent construction job? – banned 1995
IDJ: In Hong Kong until around the mid 1990s, curious observers and old men with nothing better to do were a familiar sight gathered at gaps in construction sites fences where amongst the usual activities they could observe a practise possibly unique to Hong Kong.
Husband and wife teams constructing large diameter, hand dug piles, known as caissons were common on most large construction sites often excavated in very difficult conditions.
They were hand dug from the top down as far as 40 metres or more, with the husband excavating and concreting the pile perimeter walls in one metre sections. The wife raised the spoil as the husband excavated, and more importantly she ensured that air was continuously supplied to the bottom of the shaft by means of a compressor and a length of rubber tube. Naturally, she also provided lunch and dinner on site.
These dedicated and skilled teams unfortunately experienced accidents which were regularly highlighted in local newspapers. Collapsed excavations, sudden water ingress or ventilation overcome by noxious gases within the ground were common dangers.
Heath and Safety at Work regulations have no doubt inhibited hand dug caisson practises. Modern hydraulic machinery has been cleverly designed to take over caisson excavation work with clamshell digging mechanisms.
HF: The HK Government enacted the Buildings (Amendment) Ordinance 1995 on 19 January 1995 to ban the use of hand-dug caissons. There were exemptions as stated below:
Buildings Dept, Ban on Hand-dug Caisson
The last occasion I saw a team (two men down the caisson with a pneumatic drill, and two women on the surface hauling up the excavated material by hand on a pulley) hand digging was when I walked over the first Ap Lei Chau bridge when the second bridge was being built. On the Ap Lei Chau side the hill slope had been cut back and a number of caissons excavated. This would have been about 1993 as the new bridge opened in 1994.
This article was first posted on 14th January 2015.
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