Edinburgh, Scotland has created a plan to cap the speed limit at 20 mph across 80 percent of its roads, including the entirety of its downtown area.  The strategy aims to improve air quality and encourage more people to walk or cycle.  Studies and public outreach, carried out as part of pilot projects undertaken for the plan, indicate that lower speed limits across the city also increase residents' perception of the safety of bicycling.  Only 18 percent of those surveyed believe the roads to be unsafe for cycling, versus 26 percent before the lower speed limits were implemented.  The most recent public poll showed that 60 percent of Edinburgh residents support the 20 mph limit.