C151B's main reason of retaining in the depot because it is pre-installed with Thales SelTrac CBTC Signalling (New Signalling for NSEWL & TWE) and there is no Legacy Signalling system installed (Westinghouse Signalling) in the train at all. New Signalling for NSL will be implemented in 2016 (later this year) while for EWL will be in 2018.
Only after NSL Signalling has been implemented, then the C151B can start mainline testing without passengers. The whole process would average out to be at least 3 months of testing. So, do expect the C151B to be debuted either this year or 2017.
Overall, C151B is the First NSEWL Rolling stock to feature the new SMRT Livery since it was first delivered. The train would come in with the new SMRT STARiS 2.0 (introduced in 2010) and the interior design is based on C151A design. C151B would be using Electric Doors instead of Pneumatic Doors which are being used by the NSEWL descendant's fleet (C151/A, C651 & C751B).
I do have exterior images of C151B and also the closeup images of the identification number. See pictures below.
15/08/15
C151B parked next to it's descendant fleet, C151A. Both trains are built by KHI/CSR Sifang:
20/10/15
C151B is rather lonely this time:
C151B is rather lonely this time:
18/11/15
C151B decided to go on test @BSD Test Track (YouTube Video)
[Exclusive Train Testing] SMRT C151B 603/604 at Bishan Depot Test Track
That's about it. I will post a new blog if there's any news about C151B coming out on mainline tracks for testing.