Originally posted by Yaimster:
Some possible scenarios ... Choose within a combo but not really all ba.
Since the kuku PTC and their 2-to-1 policy, SBS Buses can't go beyond Yishun Interchange (too bad Sembawang ...)
1. Extend SBS 45 from AMK Depot to Yishun Interchange to make 26.5+8 = 34.5 fare stages total. To compete certain parts of SMRT 853, its extended route, and 854

.
2. Extend SBS 103/103W so that it go past Seletar Airport to Seletar Country Club, Yishun Avenue 1 (via Orchid Country Club), Yishun Avenue 4, Yishun Ring Road or Central, Yishun Interchange. 
Not sure about the total number of fare stages since new bus stops would have to be implemented around the Yishun Avenue 1 stretch.
3. Extend SBS 72 to Yishun to make 22+8 = 30 Fare Stages total.Woot ... B9TLs in Yishun

, would help complement, not compete, 854 in Hougang.
4. Extend SBS 76/135 to Yishun Interchange.Sounds far-fetched, but 853 would be affected by the Circle Line Rationalisation Exercise. If 853 is removed instead of being amended (to perm 853C) then 76/135 would help cash in the golds, just like how 16 replacing 608.
Ok. Let me present my thoughts.
1. This idea is not bad as this new extended service 45 doesn't really duplicate from AMK Ave 6 onwards to Upp East Coast. It provides a direct link from Yishun to AMK Ave 10. Provides a direct link from Yishun to Lor Ah Soo.
The only problem in my opinion is that it duplicates 851, 852 and 853 from AMK Ave 6 (Anderson Junior College) to Yishun which is about 7.5 stages.
2. By referring to The Street Directory by Mighty Minds, you need to travel Seletar Club Rd to link up to Yishun Ave 1. Besides, there is a gate between West Camp Rd and Seletar Club Rd at the northern junction of the circle roundabout. In addition, if 103/103W takes this route, it will skip Seletar Airport.
In my opinion, the major problem of idea No. 2 is the demand of the route. Judging from the timings and freq of 103W, the demand of commuters goign from Serangoon to Seletar Airport is not high in my opinion. Passengers going from Seletar Airport to Yishun can take 103W to Jalan Kayu and transfer to 858 or 39 instead.
From Yishun to Fernvale, 854 provides a direct link. 853 serves from Yishun to Serangoon Central. So, what is remaining is the YCK rd from Bowen to Serangoon Stadium.
As 103/103W is a SBST service, I don't think this service can go into Yishun Ave 4 or St 61 to serve Yishun residents. Thus, I feel that this idea is not really feastible to carry out.
3. I feel that this idea is gd as it provides a direct link from Yishun to AMK Ave 5 industrial areas, Hougang Ave 9 and Hougang Ctrl. The only problem which I think is the same as idea 1, duplication of 851, 852, 853 from Yishun to AMK Ave 6 Anderson Junior College. I feel that this idea 3 is better than idea 1 as it duplicates the least with SMRT Yishun trunk services. Demand for this service in my opinion will be rather healthy.
4. I dun think service 76 can be extended to Yishun as it will be too long for a loop service in terms of a trip from Yishun to Siglap Rd. The total fare stages for 76 then will be 49 + 15 = 64 stages. The extension of 135 to Yishun will heavily duplicate 853 if it is extended through AMK Ave 8, Ave 3, Ave 6 Lentor Ave and Yishun. Besides, 853 goes to Marine Parade in Sundays and Public Holidays using Amber Rd, Marine Parade Rd, Siglap Rd which 135 passes by them too.
Just a thought.

On the whole, in my opinion, idea 3 is the best.