THE Government will hire a consultant to study two possible corridors for the Cross Island Line to span Singapore's largest nature reserve.
One cuts directly across the Central Catchment Nature Reserve, the other skirts south of it.
The Land Transport Authority (LTA) yesterday called a tender to study, among other things, the potential environmental impact of the train line being built in either.
In a statement, it said it expects to hire a consultant by the second half of this year and complete the study in 2016.
The findings, along with other factors such as cost, travel times and land use considerations, will help the Government decide the line's alignment, it said.
Senior Minister of State for Transport Josephine Teo said in a Facebook post yesterday that an environmental impact study of such a scale was new for rail development in Singapore.
"But it is necessary because the reserve is special," she said, adding that there will be no soil surveys or physical works in the reserve until the consultant gives its input.
The 50km line linking Jurong to Changi was announced in January last year and is expected to be completed by 2030.
Nature groups were dismayed that a section of the line was apparently slated to cut through the reserve. They said it would harm flora and fauna there. The Government said later that the route had not been finalised.
The Nature Society (Singapore) proposed two detours north and south of the reserve.
It estimated that the southern option along Lornie Road would add just 2km and four minutes to travel time, but nearby residents were worried that it could affect their homes.
LTA chief executive Chew Hock Yong said the authority has worked with residents and nature groups over the past eight months to address their concerns. "This study is only one of the inputs that will be considered before an eventual decision is made," he added.
Among other things, the consultant will carry out a "baseline evaluation" of the existing ecosystem and physical conditions along the two proposed corridors.
This work will be aided by an existing 120-page report setting out some 400 tree species, 400 insect species, 200 bird species and 150 mammal and amphibian species in the reserve.
Nature Society (Singapore) spokesman Tony O'Dempsey, who was involved in the report, said that it was not comprehensive and that the consultant should "document every single thing" in the areas that could be affected by the train line.
The LTA said yesterday it will start a separate engineering feasibility study for the Cross Island Line by the second half of this year for stretches outside the reserve. This is also expected to be completed in 2016.