eliminating through-traffic in central areas and shifting short automobile trips in the central area to walking, bicycling, and public transportation, significantly reducing cold start and evaporative emissions. Reducing central area traffic and increasing street space dedicated to walking, bicycling, and public transportation makes these alternatives more attractive and diminishes parking requirements in the central area. Success in reducing environmental impacts depends on curbing automobile-oriented peripheral development.
Göteborg, Sweden, introduced traffic cells in the mid-1970s together with priority for public transportation at traffic signals, new suburb-to-downtown express bus service, and central area parking controls. Noise was cut from 74 to 67 dB in the main shopping street, peak carbon monoxide levels dropped 9 percent, 17 percent fewer cars entered the center city, weekday transit trips to the center were up 6 percent, traffic on the inner ring road was up 25 percent, and the costs of running public transport went down 2 percent. Nagoya, Japan, introduced traffic cells in residential areas in the mid-1970s, together with a computer-managed signal system, bus lanes, bus priority at traffic signals, staggered work hours, and parking regulation. This resulted in a 17 percent increase in traffic speeds on main roads covered by the signal system, and a 3 percent increase in bus ridership. Fifteen percent fewer cars entered the central area in the morning peak, and automobile-related air pollution decreased by 16 percent (National League of Cities 1979).
The Downtown Crossing pedestrian zone in Boston, Massachusetts, is a limited traffic cell serving a core area with 125,000 employees. Eleven blocks of the central business district were closed to traffic in 1978 while steps were taken to improve transit service and parking management. In the first year, there was a 5 percent increase in visitors to the area, a 19 percent increase in weekday shop purchases, a 30 percent increase in weeknight purchases, an 11 percent increase in Saturday purchases, a 21 percent increase in walking trips to the area, a 6 percent increase in transit trips to the area, a 38 percent decrease in automobile trips to the area, and no increase in traffic congestion on adjacent streets, thanks to the elimination of on-street parking and stricter parking enforcement on nearby traffic streets.
Davis, California, a town of 50,000 people near Sacramento, illustrates a successful full traffic cell system that has cut highway