Study on Black Spots on Shizuishan-Zhongning Section of National Highway 109 in Ningxia Hui Autonomous Region

The systematic analysis method was adopted to analyze the black spots on Shizuishan-Zhongning section of national highway. Through the investigation and statistical analysis of the accident data in history, the authors have found the distinquishing method of black point-the accident accumulation frequency method(AAFM), and used this method to obtain the optimum fitting curve-Logarithmic curve. The analysis results show that the abrupt point of AAF is in 62%-63% and the critical number of accidents is 5. For the need of typical research, 27 black points on the sz section are distinquished and the contributing factors of accidents are analyzed.