M
Hong Kong Builder
One of the many tests carried out on precast roof beams before the final design was decided on.
undertaken indicate no insuperable difficulties even if continuous occupation becomes necessary.
The ground encountered in tunnelling has a bearing on the type of timbering and mode of excavation.
In soft ground fore-poling or spiling is necessary, in medium ground straight square sets with lagging are sufficient, while in the hard ground timbering is not necessary. In Hong Kong, all these types of ground have so far been encountered and it was found necessary
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to import special machinery from Manila to meet all these requirements. For soft and medium grounds pneumatic clay diggers are used. These machines are new in Hong Kong but have been used on New York tunnels to great advantage. They increase the efficiency of labour to such an extent that two men can now provide all the earth necessary to keep the mine cars filled as against a gang of eight men with picks and shovels. For hard rock, jackhammers and drif- ters are used. These machines are very effec- tive and give a rate of progress up to twenty times as fast as hand drilling with sledge ham- mers. This special equipment requires skilled labour which has been obtained from the Colony
and from Manila.
The rate at which accommodation is being provided varies from five to seven hundred people per day dependent upon the difficulties encountered.
The work of tunnel construction is executed under the direction of the Public Works Department by the Mining Department of Marsman Hongkong China Ltd. in collaboration with their Engineering Department. The work of casting the arch beams was entrusted to Concrete Products Ltd.
The drill steel used for drilling in rock is an English product being Edgar Allen's " Hollow Drill Steel pur- chased through Jardine Engineering Corp. Ltd.
MARSMAN HONG KONG CHINA LTD.
HONGKONG & SHANGHAI BANK BUILDING
HONG KONG
ENGINEERS
CONTRACTORS
MINING DEPARTMENT
MINE MANAGEMENT EXAMINATION
TUNNEL CONSTRUCTION
TRADING DEPARTMENT
IMPORTERS OF
METALS, STEEL, INDUSTRIAL CHEMICALS
EXPORTERS OF
ORES, CHINESE PRODUCTS
MACHINERY DEPARTMENT
STOCKS CARRIED OF CONTRACTORS MACHINERY
INCLUDING
HOISTS, AIR COMPRESSORS, CONCRETE MIXERS, PUMPS, TIPPING WAGGONS AND RAILS, STONE CRUSHERS, GRINDERS, WATER MEASURING TANKS, BRICK & TILE MAKING PLANTS, ETC.
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