February_1967 — Page 7

HONG KONG

A

BRIDGE in prestressed reinforced concrete was completed in November 1966 to cross the Shing Mun River at Sha Tin to connect Sha Tin with Waterloo Road in Kowloon via the new road and tunnel through Lion Rock now nearing completion and to be opened later this year. The bridge crossing will also provide an important link in the main road net- work for the proposed development of Sha Tin New Town.

The 321-0" long skew bridge has been constructed with three 107'-0" spans and has one 2-lane 24'-0" carriageway, a 13-9′′ wide water main pipe duct and a 10'-0" footpath. Piling with abutment and pier founda- tions have been completed on the downstream side for widening of the bridge to accommodate a dual car- riageway at a future date. Power and telephone cables and other ser- vices will be carried in ducts provided under the footpath.

The total cost of the bridge works including river training and dredging and the construction of approach roads and embankments was $1.8 million.

The Site

The Shing Mun River which drains the relatively flat and low-lying Sha Tin Valley rises in the eastern foot- hills of Tai Mo Shan and flows some

Far East Architect & Builder February, 1967

SHA TIN BRIDGE OVER THE SHING MUN RIVER

by

P.J. Wells, AMICE, and M.S. Leung, B.Sc., AMICE,

Engineering Development

Division,

Public Works Department, Hong Kong.

8 miles to the shallow Sha Tin Hoi Inlet and thence into Tolo Harbour. At the site of the bridge the river is tidal and during flood can rise to +11.00 Principal Datum. Although the upper reaches have been impound- ed by the Jubilee and Shing Mun Reservoirs, overflow from these and other works in connection with the Plover Cove Water Scheme can dis- charge into the river channel.

Investigation

Before design, bore holes and probes were sunk over the bridge site and both disturbed and undisturbed samples were taken at 10 feet in- tervals or at change of soil' down to depths of 70 feet. Samples indicated that at a depth of 35 feet to 40 feet below the ground level a harder stratum of stiff clayey sand underlay various silty sands. It was considered

that the bridge would require piled foundations and from a series of standard penetration tests it was estimated that piles would have to be driven to depths up to 50 feet below the ground.

Design

A design was prepared by the P.W.D. Development Division using M.O.T. H.A. loading for a 320 foot long bridge of 5 spans in normal re- inforced concrete supported on piled foundations. In view of the increas- ing use of prestressed concrete in the Colony it was decided that prelimin ary notice should be given to local contractors in order that firms in- terested would have sufficient time to prepare alternative designs for a bridge to be constructed in prestressed concrete but which would meet the original loading requirements.

Tenders were called on the R.C. design but contractors were invited to tender for alternative designs in prestressed concrete. Of six tenders received, four were for prestressed designs, none of which, for various reasons, were acceptable. Fresh ten- ders were called in October 1963 and after detailed examination and check- ing, the lowest tender submitted by Messrs. Fung Kau Kee Salvage and Engineering Company using prestress- ed concrete was finally accepted sub-

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