Vol 22 No 1 (08-2012)
Reconstruction and Improvement of Tuen Mun Road (I) - Sam Shing Hui Section (HY/2008/11)


Background

Tuen Mun Road, which was designed and built in the 1970s, is the major route connecting Tuen Mun and Tsuen Wan. It has been used for almost three decades and has demanded frequent maintenance. However, as most sections of the road had reached the end of the designed service life and are now in a state beyond economical repair. Maintenance works are no longer meant to be cost-effective. In view of this, the reconstruction and improvement works of Tuen Mun Road commenced in 2008 to upgrade the road to current expressway standards as far as practicable. The works were divided into three sections: Sam Shing Hui Section, Tai Lam Section and Eastern Section. Sam Shing Hui Section will be firstly featured.

The contract

The contract of Reconstruction and Improvement of Tuen Mun Road - Sam Shing Hui Section is numbered HY/2008/11. The contract sum is HK$1,366 million and the main contractor is China Harbour Engineering Company Limited. The project commenced in late-June 2009 and is expected to be complete in late-2014.

Tuen Mun Road - Sam Shing Hui Section is a 4.7km-long dual 3-lane carriageway from Siu Lam to Sam Shing Hui. The scope of works is to upgrade Tuen Mun Road to the current expressway standards as far as practicable, including widening of traffic lanes to expressway standard width and provision of hard shoulders and verges; and improvement of sightlines, gradients, road curvature, super elevation and so on. The improvement works also include widening of vehicular bridges, box culverts and subways, reconstruction of road pavements, installation of noise barriers, slope works and other ancillary works.

The construction time for the project is five years. Slope works, filling works and construction of retaining walls are being done in the earlier stage while road reconstruction works will be carried out subsequently. The project is now in its peak period with more than 400 workers.

Traffic lanes widening

To improve the traffic conditions of Tuen Mun Road Sam Shing Hui Section, the traffic lanes between Siu Lam and Sam Shing Hui will be widened from the current 3.3m to 3.5m, to the expressway standard width of 3.65m. Hard shoulders and verges will be constructed along Tuen Mun Road and the crush barriers will be upgraded.

Since Tuen Mun Road lies along the slopes, slopes have to be cut or filled in advance to provide the necessary space for widening works of traffic lanes. Among the 300 slopes along Tuen Mun Road, the numbers of slopes being filled and cut are 48 and 38 respectively. Ground investigation is done before slope works. Meanwhile, to beautify the modified slopes in the project, the surface of the soil fill slopes is covered with erosion mat to prevent erosion and followed by hydroseeding and planting. For rock cut slopes, the surface is sprayed with mixed fibre and soil, and followed by hydroseeding and planting.

In addition, 300m of Castle Peak Road adjacent to Tuen Mun Road will need to be shifted 4 to 6m southward to facilitate the traffic lanes widening works of Tuen Mun Road.

Widening of
Sam Shing Hui Bridge and So Kwun Tan Bridge

Affected by the traffic lanes widening works, two vehicular bridges at Tuen Mun Road Sam Shing Hui Section including Sam Shing Hui Bridge and So Kwun Tan Bridge are needed to be widened as well. Foundation works and piers construction will be done before widening of the decks. A special rapid hardening concrete mix is used to connect the new deck with the old one, of which only about 4 hours are needed for connection. This time-saving stitching method has minimized the disturbance and impact on road users.

Reconstruction of
road pavement

Reconstruction of road pavement will be carried out along Tuen Mun Road Sam Shing Hui Section and Castle Peak Road Tai Lam Section. Slope cutting works and filling of embankments will have to be undertaken first to create room for the new hard shoulder so that the number of traffic lanes will not be reduced in the daytime when traffic lanes are closed for road reconstruction works. Lane shifting for the temporary traffic arrangements, which may involve closure of two or more traffic lanes, for the reconstruction works of road pavement will have to be carried out during night time so as not to affect the daytime traffic. The material used for road pavement is a low noise material with porous friction course at the top layer, which would be able to reduce the traffic noise generated by the interaction between the road surface and the wheels of vehicles. During the road pavement works, quiet plant and mobile noise barriers are adopted to reduce noise impact on residents.

Noise barrier
(semi-enclosure)

A noise barrier (semi-enclosure) of approximately 520m long will be installed near Tsing Yung Street where many residential buildings are located. The installation of noise barrier will help reduce the noise impact from traffic on the residents. The height of the noise barrier ranges from 6m to 11m. Blue and green colours are chosen for the panels in an attempt to enhance greening effect. Some of the erection works of the noise barrier are to be undertaken during night time when road closure is implemented to minimise the effect on the daytime traffic.

Machinery

Transporting of materials is difficult as many of the working sites are located on slopes in which heavy machinery cannot be used. The contractor has imported a mini loader to replace wheelbarrows, which are relatively more time-consuming, to enhance the efficiency.

Challenges

The large area of construction site has placed difficulties and challenges to the project. In order to less affect the traffic, road closures are kept to absolutely minimum. The use of entrance/exit of construction site accesses by construction vehicles on Tuen Mun Road are limited. This limitation highly constrains the number of slopes to be carried out at one time. In most time, slope works have to be done one-by-one due to the low accessibility. During construction, Tuen Mun Road will remain to be operating with the existing number of traffic lanes during rush hours (i.e. 7:00 a.m. to 8:00 p.m. (Kowloon bound) / 7:00 a.m. to 9:00 p.m. (Tuen Mun bound)). To minimize disturbance to the traffic along Tuen Mun Road, the widened hard shoulder will be used to divert traffic as far as practicable during construction. All these constraints have tightened the schedule for construction.

On the other hand, working near the expressway has increased the risk to both workers and road users. Measures such as the use of water-filled barriers and reducing the speed limit along Tuen Mun Road are carried out to enhance safety. The first stage of temporary speed limit reduction along Tuen Mun Road between Sham Tseng and Sam Shing Hui section has been implemented from February 2012. The speed limit is reduced from 80 km/hr to 70 km/hr. The second stage was introduced in April 2012 with the speed limit between Tsuen Wan and Ting Kau reduced from 70km/hr to 50km/hr. The act has greatly reduced the possibility and seriousness of accidents. The temporary speed limits will be implemented up to the completion of the reconstruction works.

Environmental-friendly

To reduce the environmental impact brought about by the project, different measures are carried out in 4 aspects during construction. For air pollution, foggy sprinkler system is installed at most of the slopes and construction sites to moist the exposed dust and to minimize dust emission. To minimize noise impact, quiet plants are used during construction; silencers are installed on noisy equipment; temporary noise barriers are used at construction sites near residence. For water pollution, all waste water will be treated before discharging to public drains. To reduce waste, about 15% of the removed bituminous materials will be re-used for constructing the new pavement on Tuen Mun Road. The remaining removed bituminous materials will be recycled and re-used by other road works.

Community Liaison

To enable the public to better understand the details and progress of the project, the Highways Department has set up a Community Liaison Centre, with staff answering enquiries concerning the project. More information could be obtained from the bi-monthly newsletters and the project website.

Besides, the contractor has held forums in various estates along the project area to provide residents with details of the project; and meetings with Owners Corporation to collect public opinions.

Progress and conclusion

The slope works along Tuen Mun Road Sam Shing Hui section are in good progress. The foundation and piers of Sam Shing Hui Bridge and So Kwun Tan Bridge have been completed and the road widening works are in progress. Upon completion of the reconstruction and improvement of Tuen Mun Road, the traffic conditions of the road will be improved and safety will be highly enhanced.



Courtesy acknowledgement:
Highways Department
Major Works Project Management Office
for providing the above information and photos



We would like to express our appreciation to
Ir. Dr. Wong Chung-kwong Sam
Chief Engineer
Major Works Project Management Office - Highways Department
for the valuable information and support he provided during the preparation of this featuring article.