2 Project Description

2.1 Site Location and Scope of the Project

2.1.1 The proposed widening works for Tsing Tin Interchange will be undertaken at the northern part of Town Centre Section of TMR near the Tuen Mun River Channel. The location of the works area is indicated in Figure 2.1.

2.1.2 The scope of this Project as defined in this EIA report shall comprise:

(a) Widening of the 240 metre-long dual 2-lane section of TMR at Tsing Tin Interchange to a 11 m wide dual 3-lane carriageway; and

(b) Construction of associated earth retaining structures, slope works, geotechnical works, and works on environmental mitigation, landscape, drainage, road lightings, water mains and traffic aids.

2.2 Need of the Project

2.2.1 The opening of HK-SWC and DBL will increase the east-west traffic in Northwest New Territories. Most of this additional cross-boundary traffic will make use to TMR to access the urban areas.

2.2.2 The existing road section at Tsing Tin Interchange of TMR is a dual 2-lane carriageway only while the road section before and after this interchange is a dual 3-lane carriageway. The traffic condition of this interchange section will inevitably be worsened by the additional traffic from HK-SWC, therefore, traffic improvement scheme is considered necessary to relieve the traffic congestion at Tsing Tin Interchange.

2.2.3 Without the Project, TMR at Tsing Tin Interchange will be severely affected as it becomes a bottleneck due to increase traffic from HK-SWC. Long queues would be anticipated at both ends of Interchange and as a result of severely congested in TMR.

2.2.4 If there is severe traffic congestion at Tsing Tin Interchange, there would have consequential adverse air quality impacts to the nearby air sensitive receivers as the vehicles are in idling condition in traffic congestion.

2.3 Consideration of Different Alignment Options and Built-forms

2.3.1 The Project is to widen the at-grade road and construct associated earth retaining structure and proposed noise barriers. The preferred option has been developed based on the fact that this is a widening scheme with alignment essentially fixed by the existing operating highway. Major changes to the alignment would cause extensive disruption due to traffic diversions and any practicable widening design must therefore aim to minimise this. The preferred scheme was therefore developed with the objective of widening the highway symmetrically as far as possible. The present option is widening of at-grade Tuen Mun Road (Option 1). Under the terms of the EIAO there is a specific requirement for the consideration of alternative options. The following alternative options have been considered in the early planning stage in order to relieve the growing traffic volume:

(a) Option 2 - Tunnel/Under-pass

It is apparent that this option will induce less noise and air quality impacts arising from road traffic during the operation stage. However, this option is considered not viable due to the following reasons:

· Higher impact on land use;

· Higher impact on trees;

· Longer construction period resulting prolonged construction impacts;

· More C&D materials to be generated;

· Higher energy consumption during the operation of the tunnel/under-pass, e.g. tunnel lighting, ventilation etc.;

· Additional impacts on noise and air quality arising from the tunnel ventilation system, e.g. air and noise emissions from ventilation shafts at road side, portal emissions; and

· Higher construction cost.

Due to the poor soil properties in Tuen Mun area and the shallow nature of the road tunnel, only cut-and-cover method can be engaged for the construction of the road tunnel.   The trees along the existing central divider of Tuen Mun Road as shown in the sketch will be affected under this option.  The no. of trees to be affected is about 127. The drawing showing tunnel/under-pass option is shown in Appendix 2.1.

(b) Option 3 - By-pass

The introduction of additional traffic lanes by means of an elevated by-pass has been considered. The environmental impacts arising from this option are considered far more worse, details of which are elaborated below:

· Higher impact on land use;

· Higher impact on trees;

· Higher visual impacts;

· Longer construction period resulting prolonged construction impacts;

· Higher noise impact as resulted from the elevated structures;

· More C&D materials to be generated; and

· Higher construction cost.

Due to site constraints and the presence of elevated structures, additional traffic lanes in the form of a by-pass can only be fixed as shown in Appendix 2.1 which is through an existing park.   Part of the trees in the park and along the existing central divider of Tuen Mun Road as shown in the sketch will be affected under this option.  The no. of trees to be affected is about 153.

2.3.2 Comparison of three options in view of visual and landscape impacts are summarized as following paragraphs and Table 2.1.

Comparison of Visual Impacts

· Option 1 - Widening of Roads:  The widening of the existing Tuen Mun Road will involve the construction of two additional at-grade traffic lanes along the existing transport corridor.  This will affect the least amount of trees along the roadside and within Castle Peak Road (San Hui) Park among the three options.  The visual impact arising from this option is considered smaller than Option 2 and Option 3.

· Option 2 - Tunnel/Underpass:  The tunnel/underpass will be constructed using cut-and-cover method and two tunnel portal structures will be constructed at the two ends of the tunnels.   More trees along the central divider of the concerned road section than Option 1 will be affected.  The visual impact arising from this option is considered larger than Option 1.

· Option 3 - Bypass:  The bypass will be in the form of an elevated viaduct routing through Castle Peak Road (San Hui) Park.  The Park as well as the trees inside will be seriously affected.  The visual impact arising from this option is considered the most substantial among the three options.

^{Table 2.1 Unmitigated Landscape Impacts of Different Alignment Options on Landscape Resources and Landscape Character Areas}

Landscape Resources ^1(LR)/ Landscape Character Area (LCA)	Option 1 – Widening of Road	Option 2 – Tunnel/Underpass	Option 3 - Bypass
LR1 – Roadside Planting	s 34 trees will be affected.	s 114 trees will be affected	s 63 trees will be affected.
LR 2 – Castle Peak Road (San Hui) Park	s 13 trees will be affected. s 1.03 ha of open space will be temporary affected. s 0.09 ha of open space will be permanently alienated and changed to roads.	s 13 trees will be affected. s 1.03 ha of open space will be temporary affected.	s 90 trees will be affected. s 2.5 ha of open space will be temporary affected. s 0.4 ha of open space will be permanently alienated and changed to elevated carriageways.
LCA1 – Transportation Corridor	Magnitude of Impacts: Large s 34 trees will be affected.	Magnitude of Impacts: Large s 114 trees will be affected	Magnitude of Impacts: Large s 63 trees will be affected.
LCA2- Park Urban	Magnitude of Impacts: Large s A portion of Castle Peak Road (San Hui) Park near roadside will be affected. s 13 trees inside Castle Peak Road (San Hui) Park will be affected.	Magnitude of Impacts: Large s A portion of Castle Peak Road (San Hui) Park near roadside will be affected. s 13 trees inside Castle Peak Road (San Hui) Park will be affected.	Magnitude of Impacts: Very Large s A substantial portion of Castle Peak Road (San Hui) Park will be affected. s 90 trees inside Castle Peak Road (San Hui) Park will be affected.
LCA3- Tuen Mun Urban	Magnitude of Impacts: Large s Change of an existing car park to a temporary works area.	Magnitude of Impacts: Large s Change of an existing car park to a temporary works area.	Magnitude of Impacts: Large s Change of an existing car park to a temporary works area.
LCA4- Tuen Mun River Channel	Magnitude of Impacts: Small s No noticeable off-site water quality impact will be expected as the work site is about 50 m away from Tuen Munn River.	Magnitude of Impacts: Small s No noticeable off-site water quality impact will be expected as the works site is about 50 m away from Tuen Mun River.	Magnitude of Impacts: Medium s The water quality of Tuen Mun River will likely be affected by the construction activities of the by-pass which is in close proximity to Tuen Mun River.

Note 1: Please refer to Figures 10.3.1 and Figures 10.4.1 for definitions of LR and LCA.

2.3.3 Having assessed the likely environmental impacts arising from the above alternative options, it is concluded that the present option, i.e. widening the at-grade Tuen Mun Road, is the most optimum scheme from the perspectives of environmental impacts and cost-effectiveness.

2.4 Consideration of Alternative Construction Methods

2.4.1 The widening of an at-grade road of approximately 240 metres is a straight forward construction process that will not involve complicated construction sequences and activities. However, for the purpose of this EIA Study, two alternative construction methods are derived and evaluated as following:

(a) Widening and re-construction of both bounds of Tuen Mun Road simultaneously:

The most distinct advantage of this construction method is that a shorter construction period can be achieved thus resulting construction impacts of shorter term. However, there are drawbacks as follows:

· Higher impacts on noise and air quality during construction period;

· Complicated diversion schemes for traffic and utilities; and

· Higher risks to road users;

(b) Widening and re-construction of Tuen Mun Road in stages:

Under this option, the concerned section of Tuen Mun Road will be widened and re-constructed in stages, i.e. bound by bound. Though the construction period will be longer, the following advantages can be achieved:

· Less noise and air quality impacts during construction period thus more manageable;

· Less complicated diversion schemes for traffic and utilities; and

· More flexibility for tree transplanting which is a time consuming process (certain trees should be transplanted prior to any road widening work).

2.4.2 In conclusion, the impacts and risks under the latter option, i.e. to widen and re-construct the at-grade Tuen Mun Road bound by bound, are more manageable and therefore this option is adopted.

2.5 Selection of Preferred Option

2.5.1 By-pass option for the widening of TMR at Tsing Tin Interchange is the direct method to solve the traffic congestion problem in view of engineering aspects. In view of environmental aspects, the widening and re-construction of existing at-grade road section in stages would pose less environmental impacts to the surrounding environment as it would involve the least construction area and therefore this option is adopted.

2.6 Works Programme

2.6.1 The construction of the Project is to be commenced in first quarter of 2008 and be completed in third quarter of 2009.

2.7 Concurrent Projects

2.7.1 The Project may have interaction with the project of Traffic Improvements to Tuen Mun Road Town Centre Section as its boundary is located within 500m study area of this Project and its construction period would overlap with this Project by a few months. The construction period for Traffic Improvements to Tuen Mun Road Town Centre Section would commence in September 2008 and end in December 2010. The location of concurrent project within 500m of the study area is indicated in Figure 2.2.