There are 15 panels, sometimes obscured with advertising banners.
The work is quite a presence on Orchard Rd, but no one I've talked to seems to know much about the artist. According to his homepage, he has had quite a career creating art in architectural settings. Has a nice line in east/west rhetoric.
See http://www.gerardhenderson.com/SingaporeReliefs.htm for some nice photos.
(Thanks to Lai Chee Kien for pointing me to the artist's homepage.)