Following is a question by the Hon Tien Pei-chun and a written reply by the Secretary for Health, Welfare and Food, Dr Yeoh Eng-kiong in the absence of the Secretary for the Environment, Transport and Works, at the Legislative Council meeting today (December 3) :
Members of the public have told me that the volume of vehicular traffic on the Tai Tam Reservoir dam is very high every day. They are concerned that the aged dam may thus be overloaded and collapse. In this connection, will the Government inform this Council of:
(a) the date of completion of the dam, its design life and allowable vehicular traffic load;
(b) the daily average vehicular traffic on the dam; whether it has assessed the impact of such vehicular traffic on the structure of the dam; if it has, of the details of the assessment; if not, the reasons for that; and
(c) the frequency of inspection on the structural safety of and maintenance works for the dam?
(a) Construction of the Tai Tam Tuk Reservoir dam was completed in 1918. In view of the long history of the dam, it is unable to locate the relevant design calculations and therefore it cannot tell exactly what the design life and the allowable load were when the dam was designed. However, it should be noted that the existing road on top of the dam was part of the original design.
(b) The current traffic flow along the road on the dam is about 550 passenger car units/hour (two-way total) during busy periods. The structural safety of the dam under vehicle loading condition was reviewed in 1999 by a reservoir expert engaged by the Water Supplies Department (WSD). The reservoir expert conducted an analysis on the impact of traffic loadings on the dam and concluded that the dam was structurally adequate under the prevailing traffic loadings. As part of the regular safety inspection of the dam, the reservoir expert reconfirmed in 2002 that the dam was structurally safe under the current Hong Kong highway vehicle loading conditions of the road along the dam. The physical width of the road is however too narrow to permit two heavy vehicles from passing each other. Appropriate warning signs are erected at both ends to advise drivers on the narrowness of the road and to give way to buses.
(c) To maintain the reservoir dam in good condition, WSD staff carries out monthly safety inspections. Furthermore, inspections will continue to be conducted by independent reservoir experts at not more than ten-year intervals and maintenance works will be carried out as appropriate. On top of these, more frequent inspections will be conducted when necessary.
End/Wednesday, December 3, 2003