I see, the change is based on depot, not
interchange/terminal.
Sector duplication with service 156 (plus 159) is along Buangkok
Green only, after that service 88 will ply route different to the 2
services. I really think that service 88 should not turn into
Hougang Ave 4 & 8, as that make the journey loner.
(I believe SBST let service 88 turns into Hougang Ave 4 & 8
when it was first introduced because during that time (March 1999),
Buangkok Green link to Sengkang and many roads in Sengkang have not
exist yet, so no choice have to turn into Hougang in order to use
Punggol Rd which is the only road during that time for
entrance/exit into/from Sengkang.)