Vol 22 No 3 (12-2012)
Reconstruction and Improvement of Tuen Mun Road (III) – Eastern Section (HY/2007/09)
Reconstruction and Improvement of Tuen Mun Road (III) – Eastern Section (HY/2007/09)
The reconstruction and improvement of Tuen Mun Road is carried out in 3 sections, including Sam Shing Hui Section, Tai Lam Section and Eastern Section. Following the previous articles on Sam Shing Hui and Tai Lam Sections, the works of Tuen Mun Road Eastern Section between Tsuen Wan and Tsing Lung Tau is introduced this time.
The contract number of Reconstruction and Improvement of Tuen Mun Road – Eastern Section is HY/2007/09. The contract sum is HK$2,822 million and the main contractor is Gammon Construction Limited. The scope of the contract mainly includes widening of traffic lanes, slope cutting and filling, construction of retaining structure, reconstruction of at-grade roads, improvement of road safety facilities, extension of merging and diverging arrangement, noise mitigation works and landscaping works.
The contract commenced in October 2008 and is expected to be completed in late-2014. Upon completion, the traffic condition at Tuen Mun Road Eastern Section will be improved and the inconvenience to road users caused by frequent maintenance works will be reduced.
The width of the current traffic lanes at Tuen Mun Road Eastern Section is approximately 3.3m to 3.5m. After widening, the width of traffic lanes will be broadened to 3.65m. The hard shoulders will also be widened from approximately 1.5m or below to 3.65m wherever practicable. Five vehicular bridges including Tsing Lung Bridge, Sham Tseng Viaduct, Telford Bridge, Ting Kau Viaduct and Yau Kom Tau Viaduct are also widened in the project. It is estimated that the extended deck area of the bridges will be about 4,800 m2.
Tuen Mun Road is enclosed by steep terrain on its both sides. Slope cutting and filling have to be carried out first to create adequate space for widening works. The number of slope cutting and filling reach 48 nos. and 61 nos., involving volumes of approximately 470,000m3 and 310,000m3 respectively. Slope stabilization including reinforced wall and planting will proceed afterwards.
At the 1.9km eastern end section between Tsuen Wan and Yau Kom Tau, the existing slope of width from 3m to 12m on plan between the west and east bound carriageways is converted to a reinforced concrete retaining wall ranging from 1m to 7m high to provide space for road widening.
Reconstruction of at-grade pavement is carried out at Tuen Mun Road Eastern Section. The thickness of road pavement will be largely increased to cope with the current and projected traffic loads. The top pavement layer will be reconstructed by laying low noise surface material with open-texture. It provides a noise reduction of approximately 2dB(A) to 5dB(A). The use of noise absorptive material helps to redress traffic noise.
In order to ensure smooth traffic flow and to reduce potential traffic accident, the merging and diverging lanes at Sham Tseng Interchange and Tsing Long Highway exit ramp linking westbound of Tuen Mun Road will be lengthened. Moreover, a new 60m-long single-lane underpass at Sham Tseng Interchange will be constructed to improve the traffic condition. Non-blasting excavation is carried out in 4 phases with jumbo drilling machine in order to help prevent excessive ground vibration and enhance safety.
Road Safety Facilities
Apart from improving the road superelevation, horizontal curvature and sightline, road safety facilities are installed according to the current expressway standards to enhance road safety. In order to upgrade the existing road restraint system, some of the current metal fences will be replaced by concrete profile barriers with metal parapets. Stabilisation works for slopes will also be carried out. For example, the construction of baffles and rock fall fence at Tsing Lung Tau can lessen the danger caused by rock fall.
Environmental Enhancement Plans
The project concerns environmental management. A green roof is used at the site office for energy saving. Waste water treatment system is also assembled at the site area.
On the other hand, a series of greening plans will be implemented in the project. Trees, whips and shrub will be planted on slopes at roadside for slope stabilization and environment beautification. Moreover, about 10% to 15% of removed bituminous materials are reused for road pavement so that disposal of excavated spoils can be reduced. As for noise control, 12 nos. cantilevers or vertical noise barriers and 2 nos. semi enclosures, which are about 4500m and 350m in length respectively, will be installed on Tuen Mun Road at Tsuen Wan, Yau Kom Tau, Sham Tseng and Anglers’ Beach.
Temporary Traffic Arrangements
A series of temporary traffic arrangements are implemented to enhance safety of road users and workers. Firstly, traffic diversion will be implemented in order to maintain the existing number of traffic lanes as far as practicable. The widened hard shoulder will be used for traffic diversion and the traffic lanes will be shifted in stages for road reconstruction after the completion of slope cutting and filling. During the reconstruction period, water-filled barriers will be placed to separate the site area and traffic lanes. Appropriate traffic signs are erected to alert road users the arrangement.
Secondly, the temporary speed limit reduction along Tuen Mun Road has already been implemented in 2 stages. In the first stage, the speed limit along the section between Sham Tseng and Sam Shing Hui was reduced from 80km/h to 70km/h, effective on 19th February 2012. The second stage was implemented from 29th April 2012, with the speed limit reduced from 70km/h to 50km/h along the section between Tsuen Wan and Ting Kau. The original speed limit will be resumed after the completion of road reconstruction work.
The major constraint of the project is limited site access. Most of the vehicular bridges such as Ting Kau Viaduct and Yau Kom Tau Viaduct are constructed at steep terrain, which causes difficulties on the transportation of plants. In order to create site access and speed up the construction of piers and decks, temporary steel working platforms are constructed at Ting Kau Viaduct and Yau Kom Tau Viaduct.
Another difficulty is the tight construction schedule. The traffic flow of Tuen Mun Road is high during peak hours. To avoid affecting the traffic on Tuen Mun Road, closure of lanes can only be arranged in off-peak hours. It limits the time of construction works and restricts the loading and unloading activities. To facilitate the construction works, a temporary vehicular steel bridge across Tuen Mun Road at Yau Kom Tau was built to speed up delivery of construction materials and disposal of excavated spoils. Construction works are also carried out at nighttime and public holidays to minimize the impact on road users.
Keeping the impact on road users and nearby residents to minimum is another challenge to the contractor. Air quality and noise have to be strictly controlled. Quiet plants and portable acoustic enclosures are used to reduce noise impact. Intercom with earphone is equipped for site workers when construction works are carried out at nighttime. Moreover, water spray systems are adopted for construction works to suppress dust and its impact on air quality.
In order to remain a close contact with the public, Highways Department has established a Community Liaison Centre in July 2010, with public relations officers answering enquiries concerning the project. A project website is also launched to provide related information to the public. Furthermore, a bi-monthly newsletter is issued to enable the public to better understand the details and progress of the project.
Progress and Conclusion
The construction of retaining walls and noise barrier at Yau Kom Tau, road drainage and reconstruction works between Tsing Lung Tau and Ting Kau, slope cutting and underpass construction at Sham Tseng Interchange are progressing steadily. Upon completion of the project, with the enhanced road facilities and safety as well as the greening and landscaping to the environment, sustainable development is achieved.
We would like to express our appreciation to
Ir. Dr. Wong Chung-kwong Sam
Major Works Project Management Office -
for the valuable information and support he provided during the preparation of this featuring article.
Major Works Project Management Office
for providing the above information and photos