Winston-Salem, however, is one of the few places where city traffic engineers keep studying trouble spots after improvements are made, state transportation-safety officials said. The documentation is at the core of a long-running but little-known effort by city officials in Winston-Salem to make the streets safer. Over the past 17 years, the Winston-Salem Department of Transportation's Safety Improvement Program has tried to reduce wrecks at 469 intersections. Studies completed this year show that at 58 spots, the number of wrecks dropped by more than 25 percent - from 1,064 to 786, over a study period of about four years. The...