Walking along a trail near the drain near the bus stop opposite Ngee Ann poly, I was lead to this railway track. The wooden planks piled up at the side might be due to some repair work done to the track. There were many.. many of them along the track.
When fungi finds its way into trees, it begins to rot away the inner most layer of the tree (known as heartwood). Fungi enter the heartwood through broken branches either caused by pruning or weathering. Most trees will be able to survive even without the heartwood, some are not so fortunate. This tree's "death" most likely is due to uprooting caused by a storm and unlikely caused by the absence of heartwood.
Interestingly, surviving hollow trees can be a habitat for birds and frogs. Especially male tree-hole frogs in the rain forests of Borneo. They have been found to utilize the unique acoustics of hollow trees to tune the pitch of their mating calls to be louder and more appealing to females. Sounds like nature's best amplifier!