Exprimental Research On Driving Track Path On Small Radius Curve In Highway Through Town Areas

With acceleration of urbanization progress, areas nearby provincial roads, counties and outskirts have fast development. Dwelling districts built along highways increasingly expand and invade highway construction clearance. At the same time, residents' travel needs and passage needs of vehicles all rely on the same highway, which forms the highway through town areas that play two roles of highway and urban road. Problems on such highways like complicated traffic composition, land usage constraints, and low-level technologies have been existed for a long time, having great risk to cause accidents. In contrast with foreign village-across highways that have relevant design specifications or standards, the highway through town areas in China have not attracted sufficient attention. Therefore, detailed researches on highway through town areas are very necessary for ensuring safety of both vehicles and residents.At first, the paper gave a clear definition of highway through town areas and summarized historical problems and formation of China's highway through town areas. By investigation, the paper summarized common situations of highway through town areas such as invaded construction clearance, poor path planning with many curves, high proportion of non-motor vehicles and deficient traffic facilities. Due to the fact that accidents commonly occur on small radius curves, the paper chose three curves of a typical village-across highway in suburb of Beijing as its research object.Then the paper analyzed stability of vehicle running on curves from a perspective of driving behavior. It analyzed internal mechanism of driving behavior and discussed two most visible outward manifestations i.e. running speed and running track. The research on drivers' track decisions showed that there are different track types, which implies that running tracks are results of the driver's active selection.In addition, the paper conducted experiments by using of driving simulation technology. It built driving simulation scenarios with HintCAD, 3D Max Studio and SCANeR Studio respectively. Then 10 drivers were selected for driving simulation 4 times at low and high running speeds respectively. So, data of 120 groups was acquired. The paper explained the way to extract data and data difference. It divided each curve into 31 sections, which made the research data more plentiful and correct compared with previous data.At the end, the analysis on experimental data showed that the running speed has three phases of change in normal turning process and high running speeds could cause drivers' incorrect control of vehicle. Driving track path on curves have many types and respective characteristics, which can be expressed in maximum lateral offset. In addition, running speed and rate of change of curvature can have significant effects on running tracks. Based on these studies, a model of maximum lateral offset of driving track paths was built for conspicuousness verification. The concept of “Conflict Area” on curves was proposed. Based on the location where maximum lateral offset of running tracks appeared, two Conflict Areas were marked off with down direction as reference basis. At last, the safe threshold of running speed was calculated for advoiding Conflict Areas. The results can also be applicable for ordinary highways and small radius curves of mountain roads.