Traffic suddenly became thin, and the camera panned upstream: Several 
lanes had been blocked by a swarm of bicycles. Occasionally a red taxi or 
Mercedes-Benz would squeeze by along the iron fence and burst free, the driver 
holding down the horn button so furiously that he might detonate the air bag. 
Hackworth could not hear the sound of the horn, but as the camera zoomed in on 
the action, it became possible to see one driver take his hand off the horn and 
turn back to shake his finger at the mob of bicyclists.