From operational point
of view
The timing and arrangement is EXTREMELY complicated! There are much
more variations than just 179 and 179A!
But first, about 242 and 255, they have tried to keep the timings
of these services the same, so majority of the buses on these 2
services still depart on the same timings as the old timetable. The
part severely changed is the 242 or 255 crossing over to 179 part.
9187L will do 179A for 2 or 3 trips, while the 255 buses will do
179A too (not sure how many trips).
Back to 179, firstly, it seems that the buses doing 179A in PM peak
are those which don't x-over to 242. But I'm not so sure whether
this is completely true.
There are actually at least 3 types of 179 services. (4th one
unconfirmed yet)
179 - one loop around BNL
179 - down trip from inside NTU
179A - standard departure from Hall 1
179A - (unconfirmed) down trip from inside NTU
Moreover, buses aren't fixed to just one type of svc.
For example, 9092B did at least 2 trips of 179A in early PM peak,
then switched to down trip of 179, then did pure 179 rounds.
However, there are buses will do the reverse, like 9111E, 9128H,
9131Y! They do pure 179 rounds first, and then do 179A rounds later
on, from 6pm, 7pm onwards! (as observed by brotherchen)
I have no idea why SBST don't want to leave the 179A buses as they
are, and the pure 179 buses as they are, so BC don't need to keep
changing destos.
Buses doing 179A consist of both A/P and S shift buses. E shift not
so sure.
But the biggest joke I think is the timesheet arrangement. 179 I
believe has the strictest timetabling of all services.
179 now has 9 regulating points on the timesheet for a 30 - 38min
round! 
This is compared to other svcs like 334,
which was 3 fare stage points for 45mins, 333 with 5 points for
50min, 255 with 7 points for 55min.
It's rather ironic since even today, the BCs were chionging like
crazy, ignoring the timesheet. 
The timesheets are now super long, only being able to fit 6
complete 179 rounds on one page. I think there may be a 6 - 8 page
long A/P shift timesheet., or maybe a 4 page long E shift
timesheet! Maybe someone can try and take a look.
So the 179 arrnangement is super complicated, requiring all buses
to carry 179 and 179A front destos, 179 and 179A AM peak, 179A PM
peak side destos. So lots of destos required! Maybe 242 or 255
too!
