There is 51at the first portion of the orute from Hougang to
Pasir Ris except that 51 doesn't ply the Hougang Ave 8 area. rom
Hougang Ave 2 to Kaki Bukit Ave 1, there is 25, 55, 854 utilising
the whole route together with service 4. After the junction of
Hougang Ave 2 and Upper Serangoon Rd, there is 51. Anyway, it
follows 87 afterwards to Kaki Bukit Ave 1. Then, at Kaki Bukit Ave
1, it follows 58. I predict that for demand wise, it will be
moderately high from Hougang Ave 2 to Kaki Bukit Ave 1 where
residents residing at the Hougang areas take buses to the
industrial areas at Ubi. However, imagine if they are living at
Hougang Ave 8 blk 600 plus, they will prefer walking to the Hougang
Ave 2 bus stop to take 25, 55, 854 or 4 to their destinations
rather than to wait for service 4 only at the bus stop along
Hougang Ave 8.
Nevertheless, it provides a direct link from Hougang Ave 8 to Kaki
Bukit though 87 provides a link to there too from Hougang
Central.
Dun forget 88 which is there to provide a link from Hougang Ave 8
to Pasir Ris. 15 also passes Kaki Bukit Ave 1 to Pasir Ris.
On the whole, this route faces too many duplication. For the first
portion, it looks like 87 then 58. The route in my opinion is not
really economically viable to be implemented.