Cause Analysis of At-Grade Intersection Accidents and Grading Improvement Methods Research of Highways in Plain Area

At-grade intersection is one of the black points of highways in plain areas, and it is a key section of highway safety improvement. Improving safety for intersections and avoiding traffic accidents can effectively improve road safety of the plain area highway. The accident data of plain areas in Shandong Province from 2003 to 2006 was collected; accident type and the accident frequencies of different driving directions in at-grade intersections were analyzed based on statistical methods; the causes of at-grade intersection accidents were analyzed based on accident data statistics and at-grade intersection investigations of highways in plain areas; at-grade intersection grading methods were proposed based on the technical grade, traffic volume of crossing roads and the role in the network, and key points to improve the safety of different grade intersections were proposed.