2                     DESCRIPTION OF THE PROJECT

 

Location and Scale of the Project

 

2.1               The Project is located in the North Wan Chai District and will occupy the aerial space between Phase I and Phase II of the HKCEC. The new Atrium Link Extension (ALE) spanning across the water channel between Phase I and Phase II of the HKCEC will accommodate 3 main levels of Exhibition Hall Extensions. The level of the main roof of the Extension will be of similar height as that of the podium roof of the Phase I building. A northern row of permanent supporting columns will be located on land close to Expo Drive Central and similarly a southern row will land near to Convention Avenue. There will be no permanent intermediate columns in the waterway. A longitudinal section of the proposed ALE is presented in Figure 2.1.

 

2.2               Maintaining an uninterrupted pedestrian link between the Phase I and Phase II will be a necessary element of the Project. For this purpose, a temporary footbridge and a temporary working platform will be constructed. The temporary footbridge will provide alternative access for pedestrians to Phase II and the waterfront areas. These temporary structures will be supported in their construction by cylindrical marine piles which will be installed into the seabed of the waterway between Phase I and Phase II of the HKCEC. Cylindrical temporary marine piles will also be installed for the demolition of the existing Atrium Link as well as construction of the new building. These cylindrical piles will be driven into position and internal space will not be excavated, i.e. left as soil.  No soil/sediment excavation would be carried out.

 

2.3               The temporary marine piles will be removed by reverse driving using hydraulic pile driving equipment. All reverse driving equipment would be mounted on barges with no temporary support required off the sea-bed. Should difficulties be encountered during the removal of a marine pile, the pile top will be moved from side to side by the driving equipment to loosen the side friction and facilitate upward driving. The removal of the pile might leave a maximum of 800mm hole in the sea bed which will be filled with clean marine sand. The marine sand will be pumped into the hole via 150mm delivery pipes from barge mounted pumps. Double layers of silt curtain would be deployed around the pile removal works to mitigate potential water quality impact.

 

Key Project Requirements

 

2.4               The major works activity for the ALE will comprise the following:

Ÿ             Construction and demolition of the temporary footbridge

Ÿ             Demolition of the existing Atrium Link

Ÿ             Construction and demolition of a temporary working platform

Ÿ             Construction of foundations and pile caps for the Atrium Link Extension

Ÿ             Construction of superstructure for the Atrium Link Extension

 

2.5               Upon completion of the proposed ALE, Halls 1 and 2 at Level 2 and Level 5 of the Phase II development will be extended by 7,200 m2 each while Hall 3 at Level 7 will be extended by 5,000 m2. Related circulation and support areas of these Halls will be correspondingly enlarged. The total gross floor area of the Extension, including circulation and support areas, will be about 49,100 m2. The tentative work programme for extension of the Atrium Link is provided in Table 2.1. Works are expected to commence in May 2006 and to be completed by March 2009. The sequence of the major works is described below:

 

Table 2.1          Tentative Programme for Atrium Link Extension Works

                         

Construction Activity

Period

Construct temporary footbridge

May 2006 – December 2006

Install temporary marine piles for demolition of existing atrium link

July 2006 – September 2006

Construct temporary working platform

September 2006 – October 2006

Demolish existing atrium link

December 2006 – June 2007

Install permanent foundations on land

March 2007 – July 2007

Construct superstructure for atrium link extension

May 2007 – September 2008

Demolish temporary working platform

August 2008 – September 2008

Remove marine piles for working platform

October 2008 – November 2008

Demolish temporary footbridge

December 2008 – February 2009

Remove marine piles for temporary footbridge

January 2009 – March 2009

             

Construction and Demolition of Temporary Footbridge

 

2.6               The temporary footbridge will be 130m long, 14m wide and made of a steel/concrete composite construction. Located beside the construction works area, the bridge will be in use until pedestrians can use the new ALE for access.

 

2.7               Construction of the footbridge will be supported by temporary marine piles that will be driven into the seabed by percussive method. The dimension of each temporary marine pile would be 800mm nominal diameter. Details of the marine pile layout for the temporary footbridge are given in Appendix 2.1. The temporary marine piles will be removed by means of pile extraction method upon completion of the ALE.

 

Demolition of Existing Atrium Link

 

2.8               Cylindrical temporary marine piles will be installed by percussive means in the sea channel for the demolition works of the existing Atrium Link as well as to support the construction of the new building. Finishes of roof/internal/sides/break slabs will be removed in skips by forklifts and labour through hatchways down to works area for clearance. Structural steel will be cut and sheared with handling by tower cranes. The temporary marine piles will be removed when the works are completed.

 

Construction and Demolition of Temporary Working Platform

 

2.9               A temporary working platform will be constructed on a set of cylindrical piles with 800mm nominal diameter installed by percussive means. Due consideration will be given to the layout of the piles to minimise disruption to the flow of water through the sea channel. The typical bay sections of the structure, hanger trusses and the structural modules will be set up on this platform prior to being installed in place.

 

2.10            After the construction of the superstructure has been completed, the temporary working platform will be demolished. The temporary piles will be removed when the works are completed.

 

Construction of Permanent Foundation and Pile Cap

 

2.11            The ALE structure will be supported by five trusses spanning the sea channel. Since no intermediate columns will be constructed in the water, permanent foundations will rest on land on both sides of the channel. The piles on the northern side and southern side of the sea channel are anticipated to be either pre-bored H piles, large diameter bored piles or barrettes.

 

Construction of Superstructure for Atrium Link Extension

 

2.12            Having been set up on the temporary platform, the structural modules will be skidded into place for connection to the adjoining bays and existing buildings. After the superstructure has been completed, fitting out and electrical and mechanical systems will be installed mostly within the building.

 

Need for the Project / Scenarios with or without the Project / Benefits of the Project

 

2.13            Since the Hong Kong Convention and Exhibition Centre (HKCEC) was completed in 1988 (Phase I) and extended in 1997 (Phase II), demand for ever-larger trade fairs there has kept increasing. The HKCEC already operates beyond capacity during peak seasons. Several mega trade fairs hosted annually in the HKCEC for light consumer goods, such as electronics, utilize all available space, including convention halls, meeting rooms, hallways and even loading areas. Convention business, potentially very lucrative for Hong Kong, has to be sacrificed or even turned away. There are some 3,300 local companies on the waiting list of mega fairs organized by the Hong Kong Trade Development Council (TDC) alone. These exhibitors, mostly small and medium-sized enterprises, are eager to participate but are unable to because of insufficient space.

 

2.14            AsiaWorld-Expo, Hong Kong’s new exhibition facility has been opened at the airport in December 2005, would be available for various types of exhibitions in Hong Kong, especially for those that require heavy floor loading. However, this new exhibition venue cannot solve the shortage of space for mega fairs at the HKCEC. Part of the pulling power of these events, which are for light consumer goods, is their downtown convenience. The distance between the two venues is simply too great for successfully splitting the location of mega shows.

 

2.15            Trade fairs are particularly valuable to thousands of local small and medium-sized enterprises that have neither budget nor staff to travel the world in search of business orders. In the 17 years since the HKCEC opened, Hong Kong has become the undisputed trade fair capital of Asia. Trade fairs are highly effective tools for promoting Hong Kong’s leading export industries. In the past year, the TDC’s 21 trade fairs alone, attracted 20,000 exhibitors, 230,000 local buyers and 220,000 buyers from outside Hong Kong.

 

2.16            Pressure is mounting on TDC and other mega fair organizers for bigger events. The reasons are clear:

Ÿ             There are some 3,300 companies on TDC’s waiting list, alone

Ÿ             Exhibitor repeat rates of up to 90% for TDC mega shows mean the chances of getting off the waiting list are slim

Ÿ             Requests from existing exhibitors for additional booth space cannot be entertained

Ÿ             Six TDC and three non-TDC shows already have demand that exceeds all available space, including convention halls and meeting rooms

Ÿ             Few time slots remain at the HKCEC for spinning off strong product sections into separate shows, as TDC earlier did with gifts and houseware

 

2.17            Without a solution, the frustration of exhibitors will only get worse. A constant concern for local organizers is that competing trade fairs in other cities will steal Hong Kong’s waiting-list exhibitors. The next few years are crucial. Other cities in the region, with large exhibition venues already operating and expanding, are hungry for business. If Hong Kong’s mega trade fairs cannot grow, competition in neighbouring cities will be harder to beat. To pre-empt this, the supply of space at the HKCEC must be increased. The need is urgent. 

 

2.18            The Government commissioned a consultant to conduct an independent study on the overall supply of and demand for exhibition facilities in Hong Kong in the next five to ten years. Taking the consultant’s recommendation into account, the Government announced its policy support for the project.

 

2.19            TDC has looked into the possibility of expanding the halls by utilizing the space between Phase I and Phase II currently occupied by the Atrium Link. Similar to the existing Atrium Link, the new extension will span across the water channel without any structure into the water channel.

 

Design of the Project

 

Design Considerations

 

2.20            The ALE allows Hall 1, Hall 2 and Hall 3 of the HKCEC Phase II to expand southward at different levels. This will provide additional exhibition space of 19,400 m2. In this way, upon completion of the ALE, the three exhibition halls of HKCEC will be enlarged, creating space for 1,000 additional standard booths.

 

2.21            The existing major exhibition halls of the HKCEC Phases I and II are currently connected by the multi-level Atrium Link, which is used for circulation, light exhibition and registration. The proposed extension of the Atrium Link will achieve better integration of the centre, as the halls in both phases, and not just the lobby spaces, will be extended to become effectively contiguous.

 

2.22            By extending the existing Atrium Link rather than building a separate facility, many supporting spaces such as the main entrance lobby, driveways and car ramps will not need to be added as they can be shared with the existing centre. In this way, the most efficient leverage of existing facilities can be achieved.

 

Planning Considerations

 

2.23            According to the Government’s planned Wan Chai Development Phase II (WDII) reclamation, the existing water channel will be reclaimed for the Central-Wan Chai Bypass and the future surface road P2. Should the Government decide to go ahead with the WDII reclamation and the programme of the reclamation works is established, TDC will dovetail its construction sequence with the reclamation time-table. Besides, the proposed locations of the northern row of columns supporting the proposed ALE will stay clear of the eastbound slip road of the planned future Central-Wan Chai Bypass.

 

2.24            According to the current Wan Chai North OZP No. S/H25/1, the MTR Reserve for the North Island Line (NIL) falls within the proposed site of ALE. The NIL tunnel passes through the site at about -10 mPD. The proposed Extension will most probably be completed before the NIL implementation as there is no definite programme for the construction of NIL at present. It has been agreed in principle with Mass Transit Railway Corporation Ltd. that the conflict of the southern row of columns with the NIL will be resolved by future underpinning of the foundation for the Atrium Link Extension.  

 

Environmental Considerations

 

2.25            The proposed Extension is designed to present minimal impact to the exterior appearance of the HKCEC so that the existing landmark architectural features will not be affected. The footprint has been reduced by 18% as compared with above-mentioned alternative Scheme 1 and Scheme 2. The main portion of the Extension will be of a similar height to the podium roof of the existing Phase I podium. The new Extension, which is confined within the width and rooflines of Phase I and Phase II, will not create any visual obstruction to nearby buildings. The Extension will not infringe on the visual corridor along Fleming Road towards the Harbour. Floors of the Extension are successively stepped back on the east and west elevations to reduce the scale and bulk of the new structure. The main trusses on the Extension are to be curved in order to achieve continuity of the existing roof profile.

 

2.26            The proposed Extension will not involve any reclamation. The Extension will be supported by five trusses spanning over 85 metres across the existing water channel. The northern row of the supporting columns will land on Expo Drive Central while the southern row of supporting columns will land on Convention Avenue. There will be no intermediate columns in the water channel.

 

2.27            The marine piles will be removed by means of pile extraction method upon completion of the Atrium Link Extension (ALE). No dredging of marine sediment would be required using the pile extraction method, and therefore it would not cause any adverse impact on water and sediment quality. Also, there would be no need for sediment transportation and disposal arrangement.         

 

2.28            Other environmental considerations include:

Ÿ             Steel from the existing atrium link can be re-used or recycled

Ÿ             The choice of steel for the structural framework minimises use of timber and concrete

Ÿ             The main structure can arrive pre-fabricated, mitigating on-site construction time, noise and waste

Ÿ             The ALE structure can be transported to the site by marine vessels, reducing road congestion and traffic pollutants

Ÿ             The “off-site” environmental impact for the construction of pre-fabricated structure, mainly construction noise, dust and site run-off, would not be considered significant if appropriate pollution control measures are properly implemented     

Ÿ             Glass surfaces can be coated to reduce heat penetration without sacrificing natural light

 

Indirect/Secondary Impact on Traffic Generation

 

Construction Phase

 

2.29            Vehicular trips will be generated during the construction phase by the delivery of equipment, materials and waste. The traffic impact during the construction phase was assessed during planning application under Section 16([1]). It was forecasted that the construction works would contribute a maximum 10 pcu/hour to the adjacent road network. It was concluded that such a low construction traffic flow would not cause adverse impact to the traffic.     

 

Operational Phase

 

2.30            The proposed extension will increase the floor area of the exhibition halls and this may induce an increase in traffic by the exhibitors and visitors. From TDC’s experience of vehicle management during Mega-Fairs, the sudden increase in traffic load to the surrounding road networks will be avoided by the employment of an offsite vehicle marshalling area. In this arrangement, the time and number of vehicles leaving the marshalling area and entering the surrounding road network will be under the control of the TDC management. The practicality of such measure has been proven during the Mega-Fairs held earlier in year 2005 and no traffic queue was observed.

 

2.31            The traffic generation and the effects of the mitigation measures were assessed for the planning application under Section 16(1). It was concluded that, with proper implementation of vehicle management procedures, adverse traffic impact during operational phase of the Atrium Link Extension is not expected.

           

Consideration of Alternative Project Design

 

2.32            Apart from the current design, there are two alternative schemes, namely, Scheme 1 with larger footprint without intermediate column support; Scheme 2 with the same footprint as Scheme 1 but with intermediate column support in the existing waterway between Phase I and Phase II of the HKCEC (see Figures 2.2 to 2.4).

 

2.33            With the scheme of a large footprint, the ALE would block the proposed vent building for the future MTR North Island Line. Also, it will cause visual obstruction from the nearby buildings in particular the hotels at HKCEC Phase 1.

 

2.34            Regarding Scheme 2, the presence of permanent column support may obstruct the flow and reduce the flushing capacity of the sea channel between Phase I and Phase II of the HKCEC. The changes in the flushing capacity may affect the dispersion of pollutants discharged from the nearby stormwater culverts and may affect the water quality of the nearby cooling water intakes and saltwater pumping station.  

 

2.35            In order to minimize visual impact and water quality impact as far as practicable, the current design has been proposed even though the construction cost has been increased by approximate 10% more.        

 

Consideration of Alternative Construction Method

 

2.36            Owing to the site constraint i.e. the site is mainly on and across the existing waterway, hence, the structure will more or less be supported by the roof trusses which are supported on the columns at both end more than 50m above ground, instead of some typical structures that are supported on columns.  The total span of each truss will be more than 80m.  Because of the inherent structural configuration, the top down construction method will be adopted instead of bottom up for the super structure. 

 

2.37            Method of lifting the roof trusses (exceeding 80m long, 16m high, 2,000 tons for each truss) into final positions is limited to hydraulic strand jack method.  The trusses are most unlikely be fabricated at the final positions due to high risk to connect such a large structure at the final position, 50m high from ground level.  Each truss shall only be putting together into one piece either off site or on site at ground level and then lift to final position by hydraulic strand jack method. Once the trusses are in final position, everything will then be constructed from there on downwards from roof to level 1.

 

2.38            Pilings will be placed without much allowance for variations from the conventional method.  Moving the pile rigs to the position and then drill the holes to the founding level with casings or without casings (bentonite will be used for without casing method).  It is the foundation type that would have variation in this case i.e. Bored Piles or Barrette Walls.

 

2.39            The only variations in the construction method that could be allowed is the extent of the temporary working platform over the waterway during the construction stage. Three options have been considered.

 

Option 1

 

2.40            The whole waterway would be fully covered with temporary working platform (see Figure 2.5). The bright side of this option would be a safe working environment (i.e. prevent the people working within the site from falling into the water); a stable working platform; sufficient working space (i.e. increase the resources and plants at anytime easily to cope with the various stage of construction). The down side would be over 329 nos. 800mm nominal diameter marine piles will be required to support such an extent of the platform which is not in line with the Gazette Notice No. 5415 issued in October 2005 under Foreshore and Sea-bed (Reclamations) Ordinance. The whole waterway between Phase I and II will be covered for over two years.

 

Option 2

 

2.41            The northern shoreline would be extended southwards by 15m, while the southern shoreline will be extended northwards by 7.5m (see Figure 2.6). This could be achieved by the use of temporary platform and supported on 63 nos. 800mm nominal diameter temporary marine piles.  The bright side of this option is that a total of 79 nos. temporary marine piles (including the piles supporting the temporary footbridge) will be deploy which is in line with the Gazette Notice No. 5415 issued in October 2005 under Foreshore and Sea-bed (Reclamations) Ordinance.  Due to very limited site area, most of the key elements/ components will have to constructed/fabricated off site, hence, under factory condition, the quality could be under control.  The down side would be the lack of working space for the contractor to increase resources and plants freely in order to achieve timely completion.  In regards of construction safety aspect, it is comparatively riskier than Option 1, there is still a possibility that the workers may accidentally fall into the waterway.

 

Option 3

 

2.42            Constructing a 40m x 75m platform that will be supported on 54 nos. 800mm nominal diameter temporary marine piles adjacent to the east bridge and a movable working platform resting on rail tracks (see Figure 2.7). Adding the total piles required for the temporary platform and the piles for the temporary bridge (16 nos), there will be 70 piles altogether which is in line with the Gazette Notice No. 5415 issued in October 2005 under Foreshore and Sea-bed (Reclamations) Ordinance. The bright side of this option would be easy access to the working platform at East Bridge, the extent of temporary platform can cover the complete waterway from time to time and cause less disturbance to the waterway by adopting the movable platform.  The down side would be limited working platform that cannot allow the contractor to increase his resources and plants freely to achieve timely completion.  Furthermore, it is a riskier option than option 1 from safety point of view.

 

2.43            Amongst these three options, only Option 2 and Option 3 could meet the requirement on the number of temporary marine piles as stipulated in the Gazette Notice No. 5415 under Foreshore and Sea-bed (Reclamations) Ordinance. In terms of water quality, Option 2 is preferable to Option 3 as the effective flow area in the main flow directions would be larger under Option 2.  Water quality impact assessment for Option 2 and Option 3 is presented in Section 5 of this Report.     

 


([1]) The proposed Hong Kong Convention and Exhibition Centre Atrium Link Extension – Planning Application Under Section 16 Town Planning Ordinance – Volumes 1 & 2, Prepared by Wong & Ouyang (HK) Ltd, June 2005.