The Tuen Mun South Extension project in Hong Kong, undertaken by MTR Corporation, has entered the critical stage of railway viaduct construction along the Tuen Mun River, in which foundation works and pier construction have commenced to lay a solid foundation for the superstructure construction that is planned to start by the end of this year.

Under the new wave of MTR railway projects, the Tuen Mun South Extension will extend the Tuen Ma Line southward by approximately 2.4 km from Tuen Mun Station via a viaduct. Two new stations will be constructed, including an intermediate station at Area 16 and a new terminal station at Tuen Mun South near the Tuen Mun Ferry Pier, with a targeted completion in 2030.

The Tuen Mun South Extension is designed to extend the operating railway, and the project is being built in the densely populated Tuen Mun community. During the design of the viaduct, the project team strived to minimise the impact of works on the community by reducing the number of piers and adopting a slender design to reduce the occupation of river space and avoid alterations to existing facilities on the river.

Currently, the foundation works and pier construction of the viaduct have commenced progressively along the Tuen Mun River. In order to maintain the smooth flow of the river, the design has been optimised to reduce the number of piers by approximately 10%. As a result, fewer than 30 sets of piers employing slender cylindrical and V-shaped designs will be constructed on the river, which will effectively minimise the occupation of river space.

In addition, the viaduct alignment was carefully planned to be close to the riverside, with the locations of the piers bypassing the three existing footbridges and one vehicular bridge across the river to maintain the pedestrian and vehicular flow.

During construction, the temporary working platforms built on the river occupy minimal river area, with some of the platforms supported and elevated by temporary piles to maintain unimpeded river flow. A temporary river-crossing access is also being built for the delivery of construction materials to the jobsites.

Where some of the viaduct and foundation works are in close proximity to Tuen Mun Station on the Tuen Ma Line, comprehensive risk assessments, method statements and contingency plans are in place to minimise any impact on existing railway facilities and operations.

The railway viaduct section of the Tuen Mun South Extension is approximately 1.7 km long, with about 1.3 km running along the Tuen Mun River, including an approximately 250-m-long river-crossing bridge. It is the largest river railway viaduct project undertaken by MTR in recent years.

All images: MTR Corporation