139 used to have LA... (Some services like 135 also used to have
LA. But after the LA was gone, these services became SD...)
There was a time (long ago) when I passed by the Bedok Int office
and saw a notice indicating roads unfit for DDs. If I remember
correctly, the notice included Changi Airport, Stadium Rd (the part
under Nicoll Highway), Lor Chuan (the part under Bradell Flyover),
Hendeson Rd (btw Telok Blangah Rd & Depot Rd), Siglap Rd,
Frankel Ave, South Buona Vista Rd, etc. For some roads, the reason
is obvious (low bridge, steep slope, etc). But for some roads like
Hendeson Rd & Frankel Ave, the reason is low trees. (Actually
the trees can be cropped to make way for DD, right?)