Research Of Two-lane Highway Alignment Design Method Based On The Operating Speed

Highway alignment design is based on the the premise of safe driving of vehicles, however it is difficult to achieve its continuity and balance because it is actually a control of its minimum indicators. Even though its specifications can meet current technical standards, it is still accident-prone, a phenomenon to varying degrees on the road at all levels in our country. On the issue of China's current situation and existing problems of highway linear design, the paper deals with the research work of its methods based on the running speed. The research is intended to use the running speed to check the quality of highway horizontal and vertical design,to guide linear index values,to reduce traffic accidents from the angle of linear design and all in all to achieve the basic requirements for safe driving.Through analyzing the impact of the speed factor,learning from the research results at home and abroad and starting from the actual situation of the two-lane highway, systematically the paper proposes the methods of two-lane highway running speed calculation and makes great improvement in prediction indicators and forecasting models of the expected speed, linear acceleration, the critical length of short straight line and the curve speed, the improvement can meet the requirements of two-lane highway running speed forecasting; Secondly,through analyzing the highway linear design requirements as well as the speed changes on the road at all levels,the paper proposes to take linear continuity as the basic control principle of linear design, and in accordance with the actual situation of two-lane highway,the paper deals with the control principle of speed difference based on the design speed classification, with the application of safety assessment by the highway in Gansu Province and with the combination with the statistical analysis of traffic accident data, the validity and reliability of the speed difference control standards are proved;finally,according to the limitations of the design speed in highway linear design, the paper puts forward the highway linear design method on the basis of running speed, meanwhile the process of modification of linear design is added to the current design methods, and the actual running speed is taken as the basis for the indicator values to ensure the continuity and balance of linear design.