3.1 INTRODUCTION
There are principal features inherent in various options that lead to the selection of an optimal choice for development. The various factors taken into consideration when assessing the options include:
Compatibility with the surrounding landuse
Socio-economic values in terms of employment, social impacts and contribution to the economy
Impacts to the natural environment
3.2 PROJECT OPTIONS
The objective of the proposed Project is to relieve the intolerable traffic congestion along the Damansara-Puchong Expressway whereby it will serve the similar catchments of Puchong/Damansara. The proposed KIDEX is expected to effectively reduce traffic congestion as it will link to various expressways such as the NKVE, SPRINT Expressway, Federal Highway Route II, New Pantai Expressway (NPE), KESAS Expressway and Bukit Jalil Highway.
3.3 THE NO PROJECT OPTIONS
The “No Project Option” will allow the current traffic condition from Damansara to Puchong to progressively worsen as the number of vehicles continues to increase. The traffic condition will continue to deteriorate with the increasing traffic load. It is generally accepted that traffic congestion and traffic jams have a generally negative consequence on the productivity and health of the population and environment.
3.4 ALIGNMENT OPTIONS
In choosing the best possible alignment, there were four main options considered (Option 1 to 4).
These four options considered were based on the best linkage to the existing road system. These four alignment choices that were considered are shown in Figure 3.1.
The final alignment of choice was chosen based on feasibility studies that were carried out to determine the best possible route and length for the proposed Kinrara-Damansara Expressway.
The various routes were evaluated by taking into account the physical, biological and socio-economic aspects of the existing land use without discounting the engineering aspects and budget constraints. The selection criteria that were taken into consideration are described briefly as follows:
Existing traffic conditions – The traffic flow and traffic volume of the existing route as well as the existing road system already in place. This would include traffic management
aspects anticipated during construction phase where diversion of traffic to other alternative roads may be necessary.
Engineering and design constrains - If piers are provided at the medians, then space must be available to maintain the same number of lanes by local widening or use of existing paved shoulders, if available.
Environmental factors – The distance of the alignment from the receptors is taken into consideration especially for noise sensitive receptors such as educational and religious buildings.
Existing land use and encumbrances – Existing encumbrances are crucial in determining the route as the alignment crosses an already built up city. This would include buildings, stations, utilities, petrol stations and others. The soil conditions and existing terrain such as rivers, ponds and hills are also taken into consideration.
Socio-economic Impacts – The social impacts expected from various route options will take into account two important aspects which are:
i) Where a property is directly affected and will require acquisition. This will inevitably lead to other issues such as the relocation of occupants or buildings which is generally not accepted by affected communities. Another set of social problems will also arise where acquisition of vacant Government land occupied by squatters is necessary. Overall Weightage Overall Weightage Overall Weightage
Traffic Study 14 8 13
Table 3.1 : Feasibility Matrices (cont’d)
-After taking into account the various issues discussed and the feasibility matrices, it was decided that the proposed Option 3 alignment route is the preferred option as it scored the highest compared to other options.
3.5 CONSTRUCTION OPTIONS
Various construction options were considered, that may have potential impacts on the environment, and would be mainly in regards to the foundation works as the alignment will be fully elevated and some form of pilling works will be required. The type of piling method considered are bore piles, micro piles, driven piles and hand-dug caisson. The choice of the method will depend on the site condition. The pros and cons of each of the pilling methods are briefly discussed as follows:
Bore piles – Usually used for medium sized in-situ concrete piles with diameters ranging from 300 mm to 900 mm. The use of drilling rigs with appropriate capacity is required. Due to rapid development of highly effective drilling equipment, this pilling method is widely used. This method generally has lower noise emission and vibration as compared with driven piles.
Driven piles/percussion piles - Installation and equipment requirements for this economical method are relatively simple but the noise and vibration generated are much higher than bore piles and restricts its use in heavily built up urban areas.
Micro piles/mini piles – Convenient to be used in confined sites with difficult access and limited working space. Uses drilling machines whereby steel pipes are inserted into the ground and grouted as a pile. The drilling produces limited disturbance (basically vibration free). Relatively lower bearing load.
Hand-dug caisson – No heavy equipment is required except power tools. Can work on a number of piles at the same time as it does not require drilling rigs. Requires very little working space and allows for works to be carried out at steep areas. Low in vibration and noise. The only drawback is that it can be potentially dangerous for workers working inside the caisson if proper safety measures are not taken.
Other construction options for the ground treatment works include piled embankment, stone columns and soil replacement depending on the engineering assessments and tests carried out.
The use of different types of retaining walls such as reinforced soil wall, reinforced concrete wall and geo-synthetic wall will also be chosen and implemented based on the height requirements and site conditions.
Figure 3.1: Alternative Alignments for the Proposed Project