Since the SCL traverses the developed urban areas across the territory, most of the tunnels and stations will be constructed underground. The construction works include excavation of rail tunnels, pedestrian subways and underground stations (Kai Tak Station, To Kwa Wan Station, Ma Tau Wai Station and Exhibition Station) as well as the extension of existing Hung Hom and Diamond Hill Stations and stabling sidings, viaducts and an elevated station (Hin Keng Station). The construction method(Drill-and-Blast method, Cut-and-Cover method, Tunnel Boring or Immersed Tube Tunnel) to be adopted will depend on various factors, such as topography and geology, etc,
7 tunnel boring machines (TBMs) will be used to construct the tunnels for SCL project; 4 are for Kowloon and 3 are for works on Hong Kong Island. The first TBM is expected to be launched in the 2nd quarter of 2014 for the section between Ma Chai Hang and Diamond Hill Station. One of the TBMs for tunnels between Diamond Hill Station and Kai Tak Development Area is refabricated in Hong Kong, which is the first in ten years for railway projects.
Tunnel Boring Machine (TBM) is specially designed for constructing tunnels which could perform different functions during tunnelling works. With a large rotating steel cutter head at the front of the shield, TBMs can pass through different types of soil, rock or mixture of both. The TBM can excavate and remove excavated materials, and at the same time install the reinforced concrete lining of the tunnel as it progresses. The use of TBM requires relatively less works area than cut-and-cover method, thus minimizing the impact to the public facilities and traffic of nearby area.
A shaft is built for delivering the components of the TBM from ground level to the tunnel level for assembly. As the TBM pushes forward, the excavated materials will be transported to the rear end of the TBM for removal via the vertical shaft.
|Sections using tunnel boring machine||Total Boring Distance||No. of TBM used|
|Ma Chai Hang Playground||↔||Diamond Hill Station||1.7km approx.||1 (up and down track)|
|Diamond Hill Station||↔||Kai Tak Development Area||1.5km approx.||1 (up and down track)|
|To Kwa Wan Station||↔||Ho Man Tin Station||3.2km approx.||1 up track 1 down track|
|Police Officers’ Club||↔||Exhibition Station||1.2km approx.||1 up track 1 down track|
|Convention Avenue||↔||Admiralty Station||0.9km approx.||1 (up and down track)|
Video for Tunnel Boring - Tunnel Boring Machine (In Cantonese only)
Drill and Blast
For underground tunnel sections in rock, excavation is undertaken using the drill and blast method; those include:
- Tunnel between Hin Keng and Ma Chai Hang Playground
- Overrun tunnel from the south of Admiralty Station
The drill and blast method is a proven and commonly used rock tunneling method worldwide and in Hong Kong, such as the construction of several underground stations including Quarry Bay, Tai Koo, Fortress Hill and North Point Stations on the Island Line. Less works site is required for this method, and hence generates less disturbance to the vicinity.
MTR Corporation is very experienced in this form of construction for building railways in Hong Kong. Detailed assessments are carried out along the route before deciding on the method of excavation used. Monitoring points will also be installed to determine any possible impacts on adjacent building structures and ensure the public safety.
1. Drill holes in tunnel surface and install explosives.
2. Detonate the explosive.
3. Remove spoil from tunnel.
4. Install support to the tunnel and prepare for the next blast.
The use of explosives is governed by the Dangerous Goods Ordinance and subject to the stringent control by the Mines Division of Civil Engineering and Development Department (CEDD), the Fire Services Department and the Hong Kong Police Force. Suitably qualified professionals will be employed for the blasting operations and a set of stringent control measures in accordance with the Buildings Ordinance and relevant statutory requirements will be implemented.
Drill and Blast Method Procedure
(In Cantonese only,
with English subtitle)
Video for Blasting Works
(In Cantonese only,
with English subtitle)
Cut and Cover
For shallow excavation in soft ground cut and cover method is used. All SCL stations (except Hin Keng Station) will be constructed by Cut and Cover method.
- Tunnels connecting to Kai Tak Station;
- Tunnels connecting to Hung Hom Station;
- Tunnels between HKCEC old and new wings.
Immersed Tube Tunnel
A 1.3km SCL cross-harbour tunnel across Victoria Harbour will be built by using immersed tube tunnel comprised by immersed tube units precasted at the casting yard. The length of each unit can reach 150 metres. The immersed tube units will be towed to the construction site at Victoria Harbour by sea.