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Following is a question by the Hon Frederick Fung and a written reply by the Secretary for Transport and Housing, Professor Anthony Cheung Bing-leung, in the Legislative Council today (December 11):
Question:
Earlier on, some residents of the Mid-levels on Hong Kong Island have relayed to me that due to a prolonged lack of maintenance, many vehicular flyovers and footbridges (bridges) in the district look dilapidated, and problems of water seepage and concrete spalling have even been found in them. In this connection, will the Government inform this Council:
(a) whether it currently maintains a list recording information on those bridges which have been in use for several decades throughout Hong Kong, including their maintenance conditions, the commissioning dates, designed lifespans and safety factors adopted at the design stage, etc.; if it does not, of the reasons for that;
(b) of a list of bridges having reached their designed lifespans;
(c) of the procedure for repair and maintenance currently in place to ensure that bridges having reached their designed lifespans can continue to be used safely; and
(d) whether any mechanism is currently in place to determine the demolition or reconstruction of bridges built in accordance with outdated design standards or excessively low safety factors; if such mechanism is not in place, of the reasons for that?
Reply:
President,
Our response to the various parts of the Hon Frederick Fung's question is set out below in the order which they are raised.
(a) The Government has all along attached great importance to the safety of flyovers and footbridges. The majority of public flyovers and footbridges in Hong Kong, about 2 000, are maintained by the Highways Department (HyD). Apart from carrying out regular inspection, maintenance and repair for the bridge structures, the HyD has also set up a database detailing information such as commissioning dates and design loadings, as well as records of inspection, maintenance and repair of these structures for effective monitoring of their structural condition and planning of maintenance works.
(b) The design life of a bridge is a conceptual parameter adopted in bridge design, which does not represent the actual service life of the bridge. At present, the design specification of the HyD stipulates a design life of 120 years for bridges, which is mainly used for assessing various loadings and environmental factors that a bridge should appropriately be designed for their encounter over its service life. As for the actual service life of a bridge, it depends mainly on the bridge's actual structural condition. Through regular inspections and timely maintenance and repair, we can maintain the bridges in good structural condition. Under such circumstance, the actual service life of a bridge may generally attain or even extend beyond its design life.
(c) Bridge structural inspections undertaken by the HyD are carried out by professionally qualified independent inspection consultants specialised in bridge inspection under the supervision of the HyD. Such inspections are mainly divided into the following four types:
(1) Six-monthly inspection
It mainly involves visual inspection of the condition of the deck facilities, main structures and ancillary components of a bridge to check if there is any noticeable damage requiring follow-up actions.
(2) Biennial comprehensive inspection
It mainly involves a comprehensive check of the condition of the main structures and ancillary components of a bridge via close visual inspection. Detailed tests, such as those on concrete strength, are carried out as necessary to ascertain the current condition of the bridge and to collect relevant data for subsequent analysis and assessment of its structural condition.
(3) Ten-yearly principal inspection
Principal inspections are carried out in phases by the HyD to check the main structures and ancillary components of bridges in use for over 30 years. In addition to close visual inspection, the inspection consultant also examines the hidden components of the bridge by removing the decorative cladding panels and covering materials. The principal inspection also covers certain detailed tests such as those on concrete carbonation, chloride content and adequacy of reinforcement cover, with a view to assessing the condition of the bridge. In general, the HyD does not need to close a bridge for such inspection and testing but may have to implement traffic diversion measures as necessary.
(4) Special inspection
On top of the above three regular inspections, the HyD will conduct a special inspection for a bridge if particular problems are identified during inspections or it is found to have been affected by serious accidents such as fire, flooding or construction incidents nearby, so as to ascertain the loading capacity and structural condition of the bridge. The HyD maintains a detailed record of the structural condition of all flyovers and footbridges which are under its maintenance purview. Any damage to the bridge structures, once identified, will be repaired immediately by the HyD. The HyD will also consolidate information including reports by bridge inspection consultants, relevant records of maintenance and repairs as well as level of utilisation for subsequent analysis and assessment of the structural condition of individual bridges, in order to facilitate the planning of medium- and long-term maintenance works and formulating relevant maintenance and repair proposals for upkeeping the bridges in good condition for safe use by the public.
(d) By means of the above regular inspections, maintenance and repair, the HyD ensures that public flyovers and footbridges are safe to use. Based on past records, no flyover or footbridge has been demolished and rebuilt due to variation of design standards or issues in relation to safety factors.
Ends/Wednesday, December 11, 2013
Issued at HKT 12:01
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