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Following is a question by the Hon Lau Wai-hing, Emily and a written reply by the Secretary for Transport and Housing, Ms Eva Cheng, at the Legislative Council meeting today (March 12):
Question:
Regarding the maintenance and repairs of elevated roads, will the Executive Authorities inform this Council:
(a) of the current number of elevated roads completed more than 35 years ago; the respective average daily numbers of vehicles using them and the respective percentages of those which are private cars;
(b) whether inspections into the wear and tear situation of the piles of the elevated roads mentioned in (a) have been conducted, and how repairs are carried out when wear and tear is detected;
(c) whether regular assessments of the structural safety of the piles of elevated roads have been made; if so, of the details; if not, the reasons for that; and
(d) whether proposed substitute routes have been drawn up for individual elevated roads to meet the traffic demands during the reconstruction of such elevated roads which are beyond repair?
Reply:
Madam President,
(a) Elevated road bridges broadly refer to road bridges spanning other roads, railways, fairways, footpaths and cycle tracks. Currently, there are 41 elevated road bridges in Hong Kong completed more than 35 years ago, of which 39 are located in urban areas and two in the New Territories. Transport Department conducts surveys annually on road traffic flow on a sampling basis according to statistical requirements. Since one of the purposes of the surveys is to assess whether the design capacity of the roads can cater for the actual aggregate vehicular flow, usually only the aggregate vehicular flow on roads is computed but not the respective percentages of various categories of vehicles. Existing information and traffic flow of elevated road bridges completed more than 35 years ago are tabulated in the Annex.
(b) Regardless of the year of completion of an elevated road bridge, Highways Department (HyD) will carry out an inspection biannually. Engineering personnel will conduct checks and identify problems, such as the presence of cracks or spalled concrete, on the structural surface of different parts of the elevated road bridge including its columns and decks. Repair works will be arranged as required. To fix cracks, synthetic resin will be injected into the cracks to prevent the entry of air and water and thus subsequent oxidation with reinforcement. As for concrete spalling, after removing loose concrete, anti-corrosion primer will be applied on exposed reinforcement and spalled areas will be repaired with epoxy resin or polyester resin. In case of more severe defects, further in-depth inspections will be conducted and appropriate strengthening works will be carried out if necessary.
As for the piles which are buried underground and cannot be inspected directly, the engineering personnel will look for abnormalities in the overall structure of the elevated road bridges during inspections, such as abnormal settlement of the bridge decks. Upon identification of such structural abnormalities, further in-depth investigation would have to be conducted. Foundation strengthening works will be carried out if structural problems of the piles are confirmed. During regular inspection and maintenance of elevated road bridges in the past, no signs of pile abnormalities have been detected by the engineering personnel.
(c) Regardless of the year of completion of an elevated road bridge, HyD will conduct more detailed inspection biennially. Apart from the items for checking set out in (b), in-depth tests, such as those on concrete carbonation levels and chloride content, will be carried out as required. The engineering personnel will assess the structural safety of elevated road bridges based on observations during on-site inspections and results of the above tests.
(d) With appropriate maintenance and repair, these elevated road bridges are kept in good conditions. If reconstruction of an elevated road bridge is required in the future, temporary traffic arrangement, including the setting of diversion routes, will be prepared in advance to cater for the traffic demand during construction stage.
Ends/Wednesday, March 12, 2008
Issued at HKT 17:39
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