Er wait? This kind of thing very hard to say one, maybe top
housing agents or some rich land prospect companies can tell
you.
Eg i'm living in serangoon, super lousy interchange. Then 7
years back NEL started running, then circle line. Plus now got a
damn big mall across the road now nEx or something.
Anyway can track here,
http://www.ura.gov.sg/student/planning_areas/sembawang.htm, and i'm
sure the people at speakers corner got some stuff to say too.
cheers.
Anyway i think punggol is able to get all the 'nice' stuff is
because they are just recently established few(?) years back, while
places like yishun semb admiralty, quite old le.