When you compare the images of the mountain in Icemoon's blog and mine, they look different. However, this is hardly surprising as even a Christmas tree can appear crooked or straight, depending on the angle you see it from.
YG scored a hattrick of right answers when he said that these high mast lightings had raising and lowering devices to facilitate the changing of light bulbs.
Some of the high mast lightings appear to have to be manually lowered (and raised) as these photos of maintenance work at the Toa Payoh Sports and Recreation Centre show:
(Notice the external straps at the side of the light mast in the first photo above. I am not surprised if someone had to climb up the mast to thread the straps and unlatch some locking device in order to bring down the lights or luminaires, as they are called.)
In contrast, the high mast of CDA has an electric-powered winch to aid in the lowering and raising of the lights. The high mast lightings are of Lycorpole brand which is marketed by a Malaysian company called Lysaght Marketing.
You can refer to a technical drawing of the 30-metre Lycorpole high mast below. (Click on the drawing to view a larger drawing.)
(Notice the "non-slip and fully self sustaining double drum winch" and the "detachable electric power tool c/w gear box".)
Now watch the YouTube video below on how they change the light bulb on top of Empire State Building. (Warning: Not recommended for viewing by people who suffer from acrophobia or vertigo.)