HyD's response to media enquiries on progress of Tuen Mun - Chek Lap Kok Link
Hong Kong (HKSAR) - Regarding media enquiries on the latest progress of the works contract "Tuen Mun - Chek Lap Kok Link (TM-CLKL) - Northern Connection Subsea Tunnel Section", the Highways Department (HyD) today (March 17) responded as follows:
As announced in the press release issued by the HyD on October 31, 2016, the completion time of the Southern Connection of the TM-CLKL project (the Project) was originally planned to tie in with that of the Hong Kong-Zhuhai-Macao Bridge (HZMB) Main Bridge, whilst the Northern Connection was originally planned to complete in the end of 2018. However, in view of the technical difficulties facing the Project, the construction programme is under high pressure, and it is believed that the Project cannot be completed according to the original target as mentioned above. The HyD also pointed out that it had been closely monitoring the progress of the works to overcome the technical difficulties, endeavouring to catch up with the progress, and carrying out a comprehensive review on the commissioning date of the Project.
Of the Project, the works of the Northern Connection Subsea Tunnel Section contract are the largest and most complicated, and the construction works have been encountering various technical difficulties.
As said in response to individual media enquiries last year, the HyD expressed that the southern landfall of the subsea tunnel will be constructed at the eastern portion of the HZMB Hong Kong Boundary Crossing Facilities (HKBCF) artificial island. However, in view of the actual site conditions, the tunnel alignment below the seawall of the artificial island needs to be lowered by approximately 10 metres to avoid passing through the stone columns thereat, so as to ensure the safe operation of the tunnel boring machines (TBMs). Also, as a result of this alignment change, amendment to the design and construction of the approximately 700-metre-long tunnel section on the artificial island is also required.
The above-mentioned amendment to the tunnel design also needs to take account of the effects due to the outward movement at the top of the steel cellular seawall of the artificial island and the more complicated than expected soil conditions at deeper strata.
To take into account the complicated technical problems, the tight construction programme and safe working methods, and the requirements of construction plant, manpower and facilities, and more, the HyD and the consultants have been actively studying several design amendment schemes with the contractor over the past year or more to ascertain the technical feasibility and cost-effectiveness of the design amendment scheme, with an aim of finalising it as soon as possible.
In mid-last year, the contractor recommended to the HyD to adopt one of the design amendment schemes under study. The HyD and the consultants requested the contractor to submit details of this recommended amendment scheme as soon as possible. However, after many months, the contractor was still unable to submit a technically feasible and cost-effective design amendment scheme.
To minimise delay to the construction programme, the HyD and the consultants issued an instruction to the contractor in early November last year, requiring it to submit in a timely manner a reasonable design amendment scheme based on the consultants' latest study results. However, after repeated urging the contractor only recently submitted a crude amendment scheme with unreasonably high construction costs. In this connection, the HyD and the consultants have carried out many rounds of discussion with the contractor, hoping that the contractor could address the matter in a co-operative manner, so as to achieve a tunnel design amendment scheme that is most cost-effective and complies with the contract requirements as early as possible, thus enabling the continued progress and early completion of the works concerned.
Based on the current situation, the two TBMs are anticipated to arrive at the tunnel ventilation shaft at the HKBCF artificial island successively in late April this year.
As the above tunnel design amendment could not be completed on time, idling periods for the TBMs will occur. To minimise this idling period, the HyD and the consultants are actively working with the contractor to explore measures for early completion of relevant parts of the tunnel design amendment so that the tunnel excavation works can continue to proceed.
Based on the latest situation, the HyD and the consultants are now carrying out a review on the completion date of the tunnel works contract. Based on a preliminary assessment, if the contractor is fully co-operative and can complete a reasonable design amendment in a timely manner and expeditiously catch up with the work progress, the HyD and the consultants believe they can strive to complete the tunnel works contract in the end of 2019 at the earliest and all construction works of the TM-CLKL Northern Connection in 2020.
At this stage, the project contingency is sufficient to cover the additional costs currently anticipated, including the associated construction cost for a reasonable design amendment scheme.
As for the TM-CLKL Southern Connection, in order to cope with the complex construction environment, the contractor is required to cast about 2 600 large-size precast deck segments within a tight construction programme, and to adopt various construction plants and methods to erect these precast deck segments. Since the viaducts are spanning the Tung Chung Navigation Channel, the Airport Express Line, the Tung Chung Line and the North Lantau Highway, the contractor shall ensure safe and proper operation of the major navigation channel, the railways and the highway during the construction. As the site area is located in close proximity to the Hong Kong International Airport, the construction works shall also be executed in compliance with the airport height restriction.
Hence, the construction works are experiencing delay due to the technical difficulties as mentioned above. At present, these technical difficulties have basically been resolved and the works are being carried out in full swing. According to the contractor's latest programme, it is anticipated that if no other unforeseen conditions arise in the future, all the works could be completed in the first half of 2019 at the earliest.
Upon the commissioning of the HZMB, the traffic between the HKBCF and Lantau Island can be routed through the existing roads on the airport island. As such, although the Southern Connection of the TM-CLKL could not be completed as scheduled, the commissioning of the HZMB would not be affected.
The HyD will continue to closely monitor the implementation of the Project, reduce the increase in construction costs as far as possible, strive to overcome the technical difficulties concerned and endeavour to catch up with the works progress so as to enable the earliest commissioning of the TM-CLKL.
Published on: 2017-03-17
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