Findings of Previous Studies

Civil Engineering and Development Department completed the Feasibility Study for Further Development of Tseung Kwan O (TKO Study) to formulate a comprehensive plan for the further development of TKO and improvement of its overall design with the vision to build TKO into a new town that can boast of its convenience, vibrancy, distinctive urban design and quality living environment. To meet anticipated traffic generated from further population intake and industrial development in TKO, the TKO Study proposed a new external road network comprising Tseung Kwan O-Lam Tin Tunnel (TKO-LTT) and CBL.

The TKO Study recommended that a new external road network comprising the CBL and TKO-LTT should be provided to meet the anticipated traffic flow. TKO-LTT is the eastern section of Route 6, a strategic link from TKO to West Kowloon. Please refer to Related Links for the details.

With completion of CBL and TKO-LTT, external heavy traffic to and from the south-east industrial area of TKO will be able to by-pass the town centre, thus minimizing adverse traffic and environment impacts on the residential areas. It will also provide relief to existing road links, particularly TKO Tunnel and Wan Po Road.

The proposed CBL is a dual-two lane road. CBL will be designed as a feature bridge across the TKO Bay to become a future landmark. In response to the aspiration of the community, a cycle track and a footpath will be included in the CBL.

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Past Progress

The Investigation and Preliminary Design (I&PD) of CBL were commenced to determine the design options, general layouts, land requirements and impacts of Cross Bay Link. The flow diagram for the formulation of Preferred Option is shown below:

We were looking at different design options of the feature bridge, including but not limited to a suspension bridge, a cable-stayed bridge, an arch bridge, etc. The cable stayed form is familiar in Hong Kong with the bridge being supported by an array of cables which fan out of the towers, the most recent addition to the family being Stonecutters Bridge. However, the scale of Cross Bay Link would be more modest and its main span length would be similar to Shenzhen Western Corridor. Arches are one of the most classical forms of construction having been used for centuries. However, modern materials and methods have given the arch form a new lease of life and many elegant arch bridges have been built around the world, such as the Butterfly Bridge completed at Bedford, UK, in 1997 which is one of the early examples of twin lean-out arch bridge. There is currently no major arch bridge construction in Hong Kong. The following were examples of some feature bridges in Hong Kong and overseas.

Tsing Ma Bridge, Hong Kong (Suspension Bridge)	Shenzhen Bay Bridge (Cabled-stayed Bridge)
The Øresund Link, Demark-Sweden (Cable-stayed Bridge)	Hulme Arch Bridge, Manchester, UK (Arch Bridge)
Tappan Zee Bridge, USA (Truss Bridge)	Kylesku Bridge, Scotland (Prestressed Concrete Box Girder Bridge)

6 design options for the feature bridge have been shortlisted from 14 possible bridge forms to meet the functional and aesthetic requirements of the project, taking account of the opinions and innovative ideas collected from the public engagement activities and the Design Ideas Invitation Event in 2009.

The spans of the main bridge are approximately 100m to 200m to maintain marine activities in Junk Bay. Either a cable stayed bridge or an arch bridge would be an appropriate form because they are reasonably economical and provide good opportunities to create an iconic landmark structure.

Common Features of Six Design Options:

1. All options provide a dual two-lane carriageway, together with a separate corridor for pedestrians and cyclists, which is generally located on the north side of the bridge facing TKO Town Centre South.
   
2. Greening and landscaping features will be provided along the highway carriageway, footpath and cycle track to provide a pleasant experience for users of the bridge, i.e. vehicle passengers, pedestrians and cyclists. In addition, greening features along the edge of the bridge will soften the bridge against the surrounding natural environment.
   
3. A transparent isolation panel along the highway carriageway to separate the pedestrians and cyclists from the road traffic will be studied once the Preferred Option has been determined.
   
4. The cycle track on the bridge will permit emergency vehicles access.
   
5. The approach viaducts have long spans to minimize the number of bridge piers in Junk Bay.
   
6. The construction methods employed for the bridge will allow safe passage of vessels in and out of Junk Bay throughout the construction period.
   
7. The adoption of energy efficient features and renewable energy technologies will be studied once the Preferred Option is determined.

We determined the Preferred Option during March to June 2010 and the selection criteria is shown below:

After detailed analysis and technical assessments, Option 5 Eternity Arch became the most prominent option in the comprehensive performance appraisal. In terms of aesthetics, rating by Sai Kung District Council and public preference survey results, it is ranked in the top amongst six options; in terms of Viability to Build and Operate, it is within the acceptable range together with other options. Therefore, we selected Eternity Arch as the preferred option for CBL.

As one of the criteria to determine the preferred option, we completed the Stage 2 Public Engagement Activities, including collection of the option ratings from District Council members, exhibitions and Public Preference Survey, to gauge the public preference on the 6 design options. We received 26 rating forms from District Council members and 3047 survey forms from the public in total and the results are shown in the figures below:

                                                                                                        *Remark : Because each person could choose more than one
                                                                                                                         option, the total percentage exceeds 100%.

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Eternity Arch - Brief

Two relatively low profile outwardly leaning arches are visually connected to carefully sculpted piers to create an eternal never-ending loop, like the one created by the cycle track loop around the shores of Junk Bay, which is completed by Cross Bay Link. The Eternity Arch leaps across the channel with an energetic movement frozen in time, which reinforces the concept of eternity. The use of a strong symbolic identity creates a landmark sculpture for the residents of Tseung Kwan O to enjoy and contemplate.

The concept for the Eternity Arch is to create an object with a strong symbolic identity. The symbol of infinity is a well known expression of eternity or never-ending, like the proposed cycle track around Junk Bay, but also of the imagination of the vision for TKO New Town. The cables attaching the deck to the arch will be invisible to distant observers, therefore the arch leaps across the channel with an energetic movement frozen in time, which reinforces the concept of eternity. Introducing the concept of eternity to a bridge structure in this way will stimulate the people visiting Junk Bay to ponder, much like the great philosophers and mathematicians who over the centuries have contemplated the true meaning of eternity. The continuous curved shape of the arch fits in well with the organic shapes of the surrounding hills. The arch is not a high arch yet it still gives the sense of unity and harmony as though it were an extension of the hillside. V-shaped piers are adopted in the approaches to the navigation bridge in sympathy with the base of the arch to create a continuous aesthetic theme for the entire crossing.

The Eternity Arch adopts a "single corridor" configuration, which means that the 34.3m-wide deck with a two-lane highway carriageway, a 4m cycleway and a 3.5m-wide footway, sails between the leaning arches as if not touching. The inclined arch concept is visually expressed with arches that reach a modest height of 70m.

As with all arches, the Eternity Arch relies on compression in the arch element to resist the weight of vehicles and the bridge deck. The compression in the arch creates a thrust at its base, which in this case, is tied back through the deck. The outward lean of the arches requires them to be constructed from lightweight steel. The base of the arch which projects from the sea is concrete to achieve a durable and long-lasting structure. To achieve the slender proportions of the arch, particularly at its base, the deck of the main bridge will be in lightweight steel construction.

The captured energy of the arch will make Junk Bay an eternal icon in itself.

[6 Bridge Design Option] [Height Comparison of Bridge Design Options] [Design Options Comparison Table]

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Ground Investigation

The ground investigation works of Cross Bay Link was completed in February 2011. Several vessels have been involved to drill 39 marine drillholes. These vessels were equipped with drilling machines which can reach 30 to 80m below the seabed to extract soil and rock samples. They were also equipped with the Global Positioning System (GPS) to accurately position the marine drillholes according to the future bridge alignment. 

Being the first time in similar infrastructure projects in Hong Kong, we adopted the “Suspension P-S Logging” technique to measure the seismic wave response of the strata in order to facilitate the bridge design to cater for the earthquake risk in Hong Kong. We also adopted the vibrocoring technique to collect marine deposit samples for laboratory testing under the environmental impact assessment study.

Drilling Vessel	Jack-up Platform

Current Progress

We are now completing the remaining work of the Consultancy including the preliminary design of the Eternity Arch and environmental impact assessment. In addition, we are addressing the comments from relevant departments on our reports to work out the detailed arrangements, including operation under inclement weather.

Apart from the work above, we are carrying out visibility measurements for CBL. In addition to engineering and aesthetic considerations, traffic safety is also an essential element in the design of CBL. In particular, heavy fog has been occasionally observed in Junk Bay which reduces the visibility in the area significantly. In view of this, we have installed a visibility measurement device at the seashore of Junk Bay and put in operation since early 2011. The visibility data will be used to design suitable traffic management scheme. 

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