Backup as in "not the main service in consideration".
There is 851 from Marymount to Yishun, there is 74 from AMK Ave
6 till King Alber Park, there is 157 from Macritchie to Bukit Batok
and several other services like 66/174 from Bukit Timah till Bukit
Batok.
Hence loading on 852 is so low. It is there because of legacy
reasons. Even if it is done away with, won't cause an eye lid to
battle except those who insist people take 852 from Yishun to Bukit
Batok (which is really a joke).
852 is deprived of demand coz its main sectors have
alternatives...
I have already said many times, 852 has great potential, it
provides foundation for DTL2 rationalisation... So that svcs like
67 and 157 could fly BKT Rd... And surplus buses could boost 852
currently unappealing freq