Vol 25 No 3 (12-2015)
Hung Hom Station and Stabling Sidings


Background

Hung Hom (HUH) Station will be transformed into a new and major railway hub under the Shatin to Central Link (SCL) project where East-West and South-North rail corridors converge. Two new levels of platforms for these corridors, together with a range of newly enhanced facilities will be provided at HUH station to allow seamless interchange for commuters travelling to every corner of Hong Kong.

At a cost of approximately HKD$5.24 billion, the scope of SCL Contract No. 1112 includes the construction of new platforms and modifying the existing HUH Station. The modification works at Station concourse level will enable easy connectivity to the new platforms and surrounding areas and create a more spacious and modern environment for passengers.

Benefits

The existing platforms for the East Rail Line, West Rail Line and Intercity Through Train are located on the western side of the Station, while the more recent modification works are being carried out on the eastern side of the station within the Pavilion Building. Concession areas, including food and beverages (F&B), as well as increased general waiting areas for Intercity Through Train passengers, will be provided, making better use of both sides of the Station.

Apart from the concessions and waiting areas, passenger flow will also be improved. Previously, the new satellite concourses were added at the mid-level walkway of HUH Station to provide additional capacity and external connections to Hung Hom and Tsim Sha Tsui areas. Yet, the provision of these satellite concourses has resulted in under-utilisation of the main podium at concourse level. Upon completion of the SCL works, a single concourse will be created whereby all passengers will be able to access the station from podium level. The modification works will also help re-establish an identity for HUH Station.

Station Design and Facilities

HUH Station will be upgraded as a railway hub with several new facilities, including two new platforms, new station connections between mid-level walkway and station concourses, additional ticket machines and entry gates. The concourse will also be refurbished and air conditioning systems will be enhanced.

The previous two sections of the F&B mezzanine level will be linked together by a connecting deck, providing a balcony environment overlooking the larger concourse hall, enhancing the look and feel of the station. Instead of two long deck structures as previously, a curved deck and oval atrium space within the central zone will be created.

Station Connection

Currently there are a number of mid-level satellite concourses and pedestrian links to the station. To the north-east, commuters can access the Hung Hom area via the mid-level walkway and Hung Ling Street footbridge. To the west, passengers can access the Hong Kong Polytechnic University and East Tsim Sha Tsui via the two footbridges spanning across Hong Chong Road. The pedestrian network at the mid-level of HUH Station will remain unchanged.

Upon completion of the modification works, the two existing mid-level satellite concourses will no longer be used. The existing mid-level walkway to the west of the station will be connected directly to the podium level through a new lift and escalators at the western side of the station. These facilities will improve access for commuters travelling from the station to the nearby Hung Hom, Cross-Harbour Tunnel Toll Plaza and East Tsim Sha Tsui areas.

Platforms

The two new SCL platforms for the East-West Corridor (EWC) and the North-South Corridor (NSC) are designed to be in the form of ‘island platforms’, where a platform at each level is located between two railway tracks. The EWC platform, for 8-car trains, will be positioned at approximately the existing ground level, while the NSC platform, for 9-car trains, will be located beneath the EWC platform. These two platforms will be located on the eastern side of the existing platforms where the current operating lines and the Intercity Through Train run.

Hung Hom Stabling Sidings

The Hung Hom Stabling Sidings (HHS) will be located east of the existing HUH Station beneath the HUH Station podium, the sidings occupying the former Hung Hom Freight Yard. The existing podium structure, and its supporting primary structures, encompass escape stairs and building services compartments to serve the topside developments. The operation of these facilities is maintained throughout construction. Construction of the Stabling Sidings has to be well-planned to minimise impacts to the adjacent properties and stakeholders. Thirteen tracks will be provided in the new Stabling Sidings and these tracks will allow space for stabling, cleaning and inspecting of the trains, with some provisions for maintenance. The full maintenance facilities for the EWC will be located at the Pat Heung and Tai Wai depots.

At the Hung Hom Stabling Sidings (HHS) the construction method, after demolition of the old Freight Yard, is bulk excavation with temporary ground support, followed by the construction of drainage and reinforced concrete structures. The required buildings and structures, including transformer rooms, are founded on Pre-bored H-piles (PBHPs) with reinforced concrete structures above. PBHPs, driven to rock, are needed as the upper ground conditions beneath the podium are mostly reclaimed soil.

Challenges and solutions

One of the main challenges for the implementation of a project such as this is to ensure that the existing structures and facilities are not affected by the construction works going on beneath. With deep excavations beneath the station and podium and the close proximity of the works to existing structures, all construction works for SCL 1112 have to be carefully considered in advance and assessed for their potential impact on the integrity and safety of the structures above.

At an overall station depth of approximately 15 m below ground, the deep excavations require ground support. Diaphragm walls are the primary form of ground support and also form the permanent station walls. The diaphragm wall construction technique used provides an effective groundwater cut-off during excavation and offers robust protection to the existing structures.

Another main challenge at Hung Hom is that the headroom available beneath the podium structure is relatively low, making construction works more difficult. Specialised plant and equipment was required to construct these diaphragm walls, excavating the soil down to competent rock. Once the excavation is completed, steel reinforcement cages were installed to give the panel the required strength. Each of these reinforcement cages can only be installed in 4m-long sections due to height restraints beneath the podium, and so a considerable number of these cages had to be joined together to create a single panel. Such works took considerable time and was labour intensive. Once the cages were installed, concrete is placed in the panel and then that panel is complete.

In a number of locations beneath the podium the required SCL alignment conflicts with the maze of existing podium foundation columns. To remove these column's sophisticated jacking systems are required to transfer the existing podium loads onto new foundation structures, clear of the SCL alignment, before the existing foundations can be removed. The structures, new and old, are monitored 24-hours per day to alert the construction teams of any potential concerns which may affect the safety of the structures.

The current HUH Station was built in the 1970s. Throughout the years, numerous major and minor alterations and additions have been made to the station prior to the SCL project. There is a huge challenge in building a modern and up-to-date SCL structure and linking the new structure to the older facilities while keeping the current Hung Hom Station in operation. To reduce any potential impact to the existing railway lines, including the Intercity Through Train, thorough planning and site surveys are required prior to commencing any works. Building Information Modelling (BIM), virtual software which can simulate the layout of a structure or building, is used which allows the construction teams to examine the structure within a computer environment before physical construction starts on site. The use of BIM allows the identification of potential clashes between various structures and to assist in designing electrical and mechanical service routes, minimising delays and errors on site.

Mitigation Measures

Under the SCL project a series of eco-friendly measures are being adopted to minimise the overall impact to passengers during construction. For example, all construction areas are separated from the public areas with fire-rated hoardings and all construction plant and activities are subject to Environmental Impact Assessment (EIA) controls. Works that might affect the public or impact train services are required to be performed during non-traffic hours, normally between the hours of 01:30 am and 04:30 am, so there are teams of workers working within HUH Station at night when the Station is closed.

With the SCL 1112 site located so close to the Victoria Harbour, considerable use is made of the Hung Hom Freight Pier for the removal of spoil and the delivery of certain materials by barge. Use of this facility takes numerous vehicles off the surrounding roads, reducing noise and traffic congestion in the area and overall reducing vehicular emissions.

Before the commencement of any construction works, the public has been informed of the planned changes to the HUH Station via different channels such as notices, media presentation, website and temporary signage on site, etc.

To maintain the quality of service, a significant number of commercial and over 50% of the F&B facilities will continue to be preserved throughout the construction period.

Progress and Conclusion

By the end of September 2015, over 56% of the works have been completed on SCL 1112. Due to the limited working space and headroom constraints beneath the podium, and ground conditions, works ahead are still challenging. Nevertheless, the construction team will continue to put endless effort to complete the works as far as practicable without compromising the safety and integrity of the Station and adjacent structures at all times.

When the works at HUH Station are completed, passengers will experience a Station with an improved ambiance and with improved facilities. Passengers using the East-West and North-South train corridors and interchanging with other forms of public transport will experience greatly improved connectivity. Congestion at peak times at the rail interchanges of Tai Wai and Kowloon Tong will be reduced and passenger travelling times will be shortened, resulting in more relaxed rail journeys for rail passengers within Hong Kong.


Courtesy acknowledgement:
MTR Corporation Limited
for providing the above information and photos