SUNDAY, MAY 5, 1985
8
NEW TUNNELLING METHOD REDUCES TRAFFIC DISRUPTION
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A JAPANESE METHOD OF CONSTRUCTING SUBWAYS WITH MINIMUM DISRUPTION OF PEDESTRIAN AND VEHICULAR TRAFFIC IS BEING EMPLOYED IN HONG KONG.
KNOWN AS THE PIPE-ROOF METHOD, IT IS BEING USED FOR WORK ON TWO SUBWAYS UNDER CHATHAM ROAD NORTH AND THE ADJOINING SLIP ROAD.
THIS +SHIELD TUNNELLING METHOD+ IS WIDELY USED IN THAT COUNTRY AND INVOLVES DRIVING STEEL PIPES HORIZONTALLY INTO THE GROUND, ALONG THE PERIPHERY OF THE TUNNEL OR SUBWAY, WITH THE PIPES BEING MECHANICALLY INTERLOCKED, SENIOR ENGINEERS MR Y.C. WONG AND MR V.J. MANSFIELD, OF THE RAILWAY DEVELOPMENT OFFICE OF THE ENGINEERING DEVELOPMENT DEPARTMENT EXPLAINED.
THE METHOD IS GAINING POPULARITY OVERSEAS, WITH HONG KONG AND SINGAPORE BEING THE FIRST TWO OTHER ASIAN TERRITORIES TO ADOPT IT.
IT WAS FIRST USED IN HONG KONG BY A JAPANESE CONTRACTOR FOR CONSTRUCTION OF AN 18-METRE-LONG PEDESTRIAN SUBWAY UNDER A RAILWAY EMBANKMENT IN TAI WAI, SHA TIN, IN 1982.
THE PRESENT JOB INVOLVES CONSTRUCTION OF TWO PEDESTRIAN SUBWAYS - ONE 38 METRES AND THE OTHER 42 METRES LONG-- AT CHATHAM ROAD, KOWLOON. IT IS THE FIRST OF ITS KIND UNDER A CARRIAGEWAY IN HONG KONG.
EXPLAINING FURTHER THE METHOD, MR WONG SAID THAT ONCE THE +SHIELD HAS BEEN FORMED, WORK CAN THEN PROCEED ON THE EXCAVATION OF THE TUNNEL OR SUBWAY, WITH STEEL FRAMES BEING PLACED TO SUPPORT THE PIPE SHIELD+. CONSEQUENTLY, THERE IS MINIMAL DISRUPTION OF TRAFFIC AND UTILITY SERVICES, AND LITTLE DANGER OF SUBSIDENCE.
THE TRADITIONAL +CUT AND COVER METHOD OF SUBWAY CONSTRUCTION, WHICH INVOLVES EXCAVATING FROM THE SURFACE IN STAGES, IS NOT PRACTICABLE IN THE CASE OF THE CHATHAM ROAD NORTH AND SLIP ROAD PROJECT, BECAUSE OF THE SERIOUS DISRUPTION THAT IT WOULD CAUSE TO THE HEAVY TRAFFIC THERE.
+THE GREATEST VALUE OF THE 'PIPE-ROOF METHOD IS THAT IT CAUSES THE LEAST INCONVENIENCE TO THE PUBLIC, MR WONG SAID.
HE SAID THIS TUNNELLING TECHNIQUE CAN ALSO BE EXTENDED TO MEET OTHER DEMANDS IN OVERCOMING SIMILAR ENGINEERING PROBLEMS
IN URBAN AREAS FOR A WIDE RANGE OF APPLICATIONS SUCH AS THE INSTALLATION OF UTILITY SERVICES SUCH AS CABLES FOR THE ELECTRICITY AND TELEPHONE SUPPLY AND PIPES FOR WATER, GAS AND SEWERAGE.
THE METHOD,