OK I promised windy I’d write this today. It’s been a while since I last determined the amount of GST to increase to get free public transport. This time we figured out that the MRT tunnel between City Hall and Raffles Place goes below the river bed of the Singapore River.
From the SLA map, we can see this is the part of the MRT tunnel, which is quite close to Raffles Place station.
A critical clue can be found in this book “Tunnels and underground structures“:
The construction of a twin 70 m long North East Line tunnels, under the Singapore River, was the second such crossing of the MRT system under the Singapore River.
Now if we look at the Singapore River and the MRT crossing points, we can see that before the North East Line crossing of the Singapore River at Clarke Quay, the only earlier point was the area we identified earlier. There seems to be a third crossing point to be constructed under ECP, between the (future) Bayfront and Promenade stations.
That’s it! Of course this is just one piece of indirect evidence; it would be more convincing to produce a variety of evidence, especially direct evidence. However, the map, together with the statement in the book does tell us that the MRT tunnel between City Hall and Raffles Place crosses below the Singapore River.