If you mean Chengal railway sleepers, they are railway ties made from Neobalanocarpus heimii (Chengal) timber, a very dense tropical hardwood native to Peninsular Malaysia.
Chengal has historically been used for railway sleepers because it offers:
* High strength and load-bearing capacity.
* Excellent natural resistance to termites, decay, and fungal attack.
* Long service life outdoors without extensive chemical treatment.
* Good dimensional stability under heavy rail traffic.
