found this on the web
Traffic Light Sculpture, Canary Wharf
Situated in the middle of a roundabout, this sculpture confuses unsuspecting motorists every day. Standing over eight metres tall it has 75 fully working traffic signal heads. It was created by Pierre Vivant and is in the shape of two plane trees. The light sequence mainly displays just red and amber - supposedly to mimic the 24 hour nature of the city behind.