| In order to determine the relationship between the headway distance and vehicle acceleration,speed and lane flow during vehicle start-up,the manual survey method is used to calculate the traffic volume,traffic capacity,location speed,and saturation headway interval at the intersection of Dawang Road with large traffic volume.For the investigation of signal timing parameters,the direction of the supersaturated west import straight line was selected as the research object.Secondly,considering the shortcomings of the GM model,based on the desired spacing and the desired speed,a car-following model based on the headway spacing in vehicle start-up is established.Thirdly,according to the field survey data,Vissim is used to simulate the output vehicle speed and headway distance.The curve fitting is performed by Matlab and Origin,and the set of solutions with the highest fitness is obtained as the final parameter.Finally,in the Vissim software,the initial headway distance and the section design flow are changed,and the vehicle acceleration,speed,and lane flow data are obtained,and the data is analyzed.The main findings are as follows:(1)A car-following model based on the headway distance during vehicle start-up is established.The model parameters are calibrated to=0.5,m=0.48,l=0.02.The coefficient of determination is 0.646.Under this group of data,the relative part of the GM model that has been calibrated is closer to the real situation.(2)When observing the relationship between speed and acceleration and headway distance,the headway distance can be divided into three sections:0.3 meters to 1.5 meters,1.6 meters to 2.7 meters,and 2.8 meters to 3.6 meters.In the same interval,the first second acceleration will be smaller than the acceleration to the desired speed.The acceleration increases sharply at a distance of 0.3 m to 1.5 m,and the growth is slower at 1.6 m to 2.7 m,and there is substantially no change at 2.8 m to 3.6 m.(3)When the acceleration of the lane is close to the saturation flow of 1770pcu/h,the acceleration does not change much with the spacing.When the headway distance is 0.3m to1.5m,the growth is drastic.The design flow rate is 1500pcu/h,1600pcu/h,and the maximum change of acceleration of 1700pcu/h is 0.27,0.31,0.34m/s~2,and the spacing is 1.6m to 2.7m.At the same time,the change is more soothing,the variation range is below 0.2 m/s~2,and the change from 2.8 m to 3.6 m is very small,and the variation range is below 0.15 m/s~2.(4)The initial headway spacing will affect the peak traffic flow and the range in which the peak occurs.The peak value and spacing of the flow change linearly,and each time the design flow increases by about 100 pcu/h,the peak occurrence interval shifts to the left by about 0.5 m.(5)The model obtains the acceleration values at different intervals by iterative method,and a similar trend to the simulation results appears. |
