MBUGUA NG'ANG'A, BIRD STORY AGENCY THE Waiyaki Way-Raphta Road roundabout in Westlands is a microcosm of the contradictions that define Nairobi's sustainable development narrative. Motorists driving down into the city stop cruising on the four-lane highway as they approach the busy intersection. Four lanes shrink to two on the off-ramp leading to Raphta Road but then traffic suddenly comes to halt because part of the road has been colonised by mutatus, Nairobi's infamous public transport minivans. It takes the constant intervention of traffic police to ensure that traffic flows smoothly. Above the honking and frayed nerves, the Nairobi Expressway stretches…