I think both can start at serangoon interchange.
U see from bishan to serangoon, 53 and 58 route is half the same,
except that 53 uses boundary all the way to serangoon central den
to upp serangoon.
58 turns into lor chuan den out to upp serangoon.
If 53 gets ammemded, 58 shld get amended because, It starts at
bishan, passes by the future lor chuan MRT den passes by serangoon
mrt. 
53 dosent pass by lor chaun.
hmm, how abt 105?
