Yesterday's report had the Land Transport Authority saying that if the Cross Island MRT Line were to skirt the Central Catchment Nature Reserve, instead of going under it, an extra $2 billion in costs could be incurred ("$2b extra cost if MRT line skirts reserve").

While $2 billion sounds like a huge sum of money, the figure should be put in proper context.

The 4km stretch of the Circle Line extension to link HarbourFront to Marina Bay, with just three additional MRT stations, is expected to cost $3.7 billion.

By contrast, realigning the Cross Island Line (CRL) to avoid the nature reserve would add an additional 5km of train line at the cost of $2 billion, which could also be used to serve new stations.

Furthermore, when stacked against the total cost of the Cross Island Line, an additional $2 billion is not likely to be a substantially large increase; the similarly ambitious Downtown Line is already estimated to cost $20.7 billion.

In another case, construction of the Marina Coastal Expressway (MCE) cost $4.3 billion. This was essentially a rerouting of the original East Coast Parkway-Ayer Rajah Expressway, so as to free up land along Tanjong Pagar for future development.

Singapore has always prided itself on planning for the long term, and the MCE is one such example.

Rerouting the CRL now to protect our nature reserve for future generations would merely be a continuation of this laudable policy.

Finally, we also spent $1 billion (not including the substantial cost of land reclamation) to build Gardens by the Bay, which, today, is a well-loved park.

The Central Catchment Nature Reserve, on the other hand, is a biologically rich rainforest that sits in the heart of our country, something that cannot be found in other world-class cities like London, New York or Tokyo.

Enjoyed by generations of Singaporeans from the very birth of our country, it is a national treasure that makes Singapore unique among the metropolises of the world.

If we are willing to spend such money on creating new nature-themed attractions, what more to protect our primeval, natural heritage inherited from our ancestors and which we can pass down to our descendants?

Jonathan Tan Yong How