for some routes, they just dont get permernent,like the nissan
uds, except for 980, 187 ,178
855 853 852 will sometimes get a few, when the smrt first transfer
them in the 2005 era, they mostly came to yishun int 852 853
855,(all new faces driving the uds at that time, now driving merc
liao 
) and sometimes 171, then after a few moths , gone to
woodland liao.
