According to a post written on SMRT's facebook page,
106 (Bukit
Batok), 190
(Choa Chu Kang), 850E (Yishun), 966 (Woodlands) and
969
(Woodlands, Sembawang & Yishun) will have Double Decker buses
with effect from this coming Monday, 18 August 2014.
At this rate (~1 month 5 days), I guess 188 (Choa Chu Kang & Bukit Batok), 951E
(Woodlands), 960 (Woodlands & Bukit Panjang) and 963
(Woodlands, Choa Chu Kang & Bukit Batok) will have Double
Decker buses with effect from around 23 September 2014.
So here is the list of buses for each service (not
confirmed)
106 - 3
190 - 3
850E - 2
966 - 3
969 - 2
* At least 13 ADLs more will be deployed on Monday
18-August.
* They should also consider adding 2 more ADLs in this round to
sv 972. But since they will want to maximize # of services for
statistics, I think 972 will get more upgrades only in Sep
phase.