Effect of reduction of speed inside the city of Amman-Jordan on reduction of road accidents

33 locations inside the city of Amman, the capital of Jordan were chosen. They were almost identical in geometrical, environmental conditions and traffic density. The speed limit on these streets was 40 km/h on one third of them, 50 km/h on the second third and 60 km/h on the last third. Accidents on these locations were recorded for one year during 1992-1993. They were 336 accidents. This represents 4.6% of the total accidents that took place inside the city of Amman. The Relationship between speed and number of accidents was drawn and analyzed while taking into consideration weather conditions (wet or dry) area of accidents (commercial or residential) geometric design of streets (straight or intersection) and fixed or variable driving speed. Results of analysis showed that the reduction of speed from 60 to 50 km/h did not reduce accidents greatly. When speed was reduced from 60 km/h to 40 km/h accidents were reduced by 75%. Reduction of speed is the most effective measure in reducing accidents inside cities.