Optimization Design And Evaluation Of Roundabouts Of Urban Road

In the early 20th century, roundabouts play an important role in the history of road traffic in the city because of the advantages of its small conflict and safety. With the rising ownership of vehicles, the saturating traffic capacity, peak-hour intersection is more close to paralysis. Aiming at this situation, the domestic practice is not generally adopted scheme comparison and roundabouts is changed to cross signal intersection directly. So there exist many problems in respect of intersection reconstruction.First of all, the author summarized and elucidated the classification and development of roundabouts from traditional roundabouts evolved into modern roundabouts and signal roundabouts. Roundabouts have changed in terms of its geometry and traffic. In addition, the author put forward the space design of modern roundabouts.Secondly, the author summarized and elucidated the timing design of roundabouts. Roundabouts signal control is divided into three types:one is turn left alone control, the second is turn left signal control at a time and the last is turn left signal control at a second time. The author deduced the timing design calculation formula of turn left signal control at a time and turn left signal control at a second timeAgain, combining with the FuZhou LuoXing west road and QingZhou road roundabouts reconstruction project, considering the project cost, capacity factors and other factors, the author selected the scheme that roundabouts is changed to cross signal intersection. By using the theoretical calculation of saturation and Vissim simulation combined with quantitative analysis, the author verified that the optimized design scheme can significantly improve the efficiency of the intersection traffic. After the transformation, the author investigated the volume of traffic again, put forward timing optimization based on Synchro, introduced the carbon emissions in evaluation factors and deduced its calculation process. As a result, it is concluded that the optimized oil consumption is reduced by 21.49% and carbon emissions by 21.47% in morning peak, oil consumption and carbon emissions are reduced by 18.08% and 18.06% respectively in evening peak.Finally, in terms of the intersection of landscape design, the author put forward a new thinking about Channelized traffic island which is planting trees, analyzed the benefits and suitable conditions of Channelized traffic island planting and elaborates the planting locations, the configuration of tree species, driving transverse spacing, safety clearance and the requirement of corresponding traffic control measures to adapt to the intersection of landscape design of this special area. In addition, combining with field investigation cases, the author made the comparison analysis.