Cross Island Line: Besides a direct and skirting route, how about a semi-direct one?

I refer to the report, “Through nature reserve or around? Residents, nature groups stick to guns on Cross Island Line paths” (Sept 3). 

The environmental-impact assessment carried out for Phase 2 of the project is commendable for its extensive coverage of the impact and mitigation for the two alignment options. It also shed more light on the pros and cons for the direct (Option 1) and skirting (Option 2) routes.

While the former would be more economical and efficient with a faster travelling time, nature groups are rightfully concerned about boring a tunnel right under the heart of MacRitchie Reservoir.

But skirting the Central Catchment Nature Reserve will cause inconvenience to residents and businesses located in the built-up areas along that route due to construction. It will also lead to longer journeys.

I wonder if a compromise can be reached by aligning the underground tunnel directly south from Bright Hill Station, going beneath part of MacRitchie Reservoir and connecting with the southern portion of the skirting option, along Lornie Road (see the yellow line in the map adapted from the Land Transport Authority website). While this would still entail tunnelling under part of the Central Catchment Nature Reserve, it has several advantages:

1. The portion under the reserve would shift further east, instead of cutting across the central core, with a section passing under a water body instead of the more sensitive forested area.
2. The worksite near Windsor Park needed for Option 1 would be shifted further out from the fringe of the reserve, or perhaps even be unnecessary altogether.
3. There will be no need to tunnel beneath the built-up area along Thomson Road, avoiding construction around existing infrastructure and incurring lower costs than the extra S$2 billion for Option 2 compared with Option 1.
4. Shorter travelling time than the additional 11 minutes estimated under Option 2 due to a less roundabout route, albeit still taking longer than Option 1.

This third option would avoid the need for worksites to be built at the more sensitive edges of the reserve as well as the potentially complex and costly site works along Thomson Road. Tunnelling under the eastern end of MacRitchie Road would also pose a lower risk of disturbance to the integrity of the Central Catchment Nature Reserve.

While studies on the two alignment options appear to be progressing well, I hope there is still time for the authorities to consider the feasibility of this alternative proposal.

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