THE alternative alignment that routes the Cross Island Line around the Central Catchment Nature Reserve could add about $2 billion to the rail project's cost, the Land Transport Authority (LTA) has revealed.
This 9km "skirting alignment" will require longer tunnels and extra ventilation facilities, compared to the 4km direct route, of which 2km will cut through Singapore's largest nature reserve, it said.
"Besides land and home acquisitions that could affect families, the extra works could incur $2 billion more in expenditure," added LTA's chief executive Chew Men Leong.
In a forum letter published in The Straits Times today signed off by him, it was reiterated that the Government is studying both alignment options and has not decided.
Since a report detailing the environmental impact of site investigation works for the project was released some two weeks ago, green groups have been lobbying for the Cross Island Line - a 50km MRT line that will span from Jurong to Changi - to be built around the reserve, instead of through it.
However, this could entail land acquisition as the MRT tunnels would pass through land occupied by homes, businesses and buildings. Residents in Upper Thomson who could be affected have called for the line to go through the reserve.
In the letter, Mr Chew said the Government will consider all factors, including the engineering feasibility of both alignments, distance and travel time for commuters, cost to taxpayers, and the impact on the Central Catchment Nature Reserve and on businesses and families.
Green groups acknowledged that the extra $2 billion and impact on residents are significant but they also called for deeper thought on the issue.
Shawn Lum, president of the Nature Society, asked: "What is the long-term cost to Singapore of potentially damaging (the) nature reserve?
"Are we setting the precedent that as long as we pledge to be careful, we can do infrastructure works in protected areas?"
Dr Lum said that rather than view the sum of $2 billion as a cost, it could be seen as an "investment into nature and heritage".
Subaraj Rajathurai, director of Strix Wildlife Consultancy, said: "This island used to be covered by rainforests, today we are down to 3 per cent.
"It has taken eons to evolve and the biodiversity is irreplaceable. Homes, however, can be cleared and rebuilt."
The LTA said the proposed tunnel beneath the Central Catchment Nature Reserve will be about 40m deep and no surface structures will be built.
A second phase of the Environmental Impact Assessment, to be completed this year, will delve into the environmental impact of the construction of both alignments.
Park Byung Joon, adjunct associate professor at SIM University, said skirting around the nature reserve involves "social costs". They include lengthening end-to-end travel time to be around four minutes more.
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