Service 27 was extended to Sengkang from Tampines in 1999 during
the 1st day SBS took over Sengkang. Further extended to Hougang in
late 2002.
Service 80 was actually a new service merged from service
84 (Hougang - WTC) and 864 (Sengkang - Marina Centre) to become
Sengkang - Harbourfront. Only services 865 and 866 were
renumbered.
As the time passes by, SBST added more routes into Sengkang.
With new bus services 83 and 87 as well as passing
by service 89 introduced. Express 501 and 502 were extended to
Sengkang from Hougang. Services 156, 159 and 163 were also extended
to Sengkang from Serangoon, AMK and Jln Kayu respectively at a
later stage.
If I am not mistaken, feeder 371's route was amended once when
Sengkang East LRT opened in 2003, which duplicated service 163 from
Sengkang to Jln Kayu and loop into Fernvale Lane. Feeder 371 was
finally withdrawn when Sengkang West Loop opened in 2005, service
163 was diverted into Fernvale Lane. Service 163A (now
163M) was introduced which was feeder 371's exact route.
Before that, service 88 was introduced, the only SBS service when
Sengkang was still under TIBS. The fleet upgraded very fast, from
non air con Scania N113CRBs to air con Volvo Olympians, B10Ms,
Leyland Olympians after a short span of about 6 months.
Service 864 had Volvo Olympians and B10Ms for its short span of
service before it merged with service 84 to become service
80.
In the 1980s, when Sengkang was not developed, there are only
two bus services to Punggol end.
Service 82, Punggol Road End - Shenton Way, mainly used Volvo
B57s and after that, Volvo B10Ms MKIIs.
Service 83, Punggol Road End - New Bridge Rd, used Mercedes
OF1413s (DM bodied) and after that, Volvo B10Ms MKIIs.