Research On The Rationality Of The Combination Of Narrow Lanes And Lateral Clearance In Urban Roads

At present,many cities have carried out pilot projects of narrowing lanes,and the application of narrow lanes has shown advantages such as stabilizing traffic flow,improving road safety and saving land resources.However,after the lane width is narrowed,the free driving space on both sides of the vehicle perceived by the driver is reduced,which may affect the speed and capacity of the vehicle.Reasonable setting of lateral clearance and lane width is conducive to maximizing the use of road space and reducing waste of road resources.Taking urban roads as the research object,this paper studies the lateral distribution characteristics of vehicle trajectories and the difference in lateral clearance required by different vehicle types.For the combination of a small vehicle lane and a large vehicle lane,a cross section with different widths of the inner lane and the outer lane is designed.And the safety is verified by simulation experiments,which provides theoretical basis for the design of lane width and other related planning.First of all,this paper summarizes the concept of lateral clearance and related theories,introduces the models related to lateral safety distance,and compares each model.On this basis,the camera method was used to investigate 6 road sections with different isolation forms and lane widths of 2.8-3.5m.This paper investigates the lateral clear distance between vehicles and the left and right marking lines,vehicle speed and vehicle type,and analyzes the influence of the type of isolation facilities and lane width on the lateral distribution of vehicle trajectories.The results show that the existence of isolation facilities usually causes vehicle trajectories to shift to the center of the road,and the degree of deviation is related to the type of isolation facilities.Vehicle trajectories are more concentrated in narrow lanes and closer to the lane center line,and the average swing is also reduced.This is due to the reduced driving free space of the vehicle,which makes the driver more cautious in changing the driving trajectory.Secondly,comparing the 3.5m wide lane with the 2.8m narrow lane,the relationship between the lateral clearance distance from the curb and the vehicle speed of different vehicle types under free-flow conditions was studied by means of mathematical statistics.The results show that the lateral clear distance between the vehicle and the curb has a linear relationship with the vehicle speed.The narrowing of the lane width and the increase of the vehicle width will lead to the reduction of the lateral clear distance between the vehicle and the curb.In addition,through the fitting of the lateral clearance and speed between vehicles in the same direction,it is found that the lateral clearance between vehicles in the narrow lane is reduced to a certain extent compared with the standard lane.Among them,the lateral clearance between small cars and large vehicles is greatly reduced.Finally,the concept and combination method of lane combination are introduced.Taking the same-direction dual-lane combination of small vehicle lane and large vehicle lane as an example,according to the division of lane functions,the two lanes are set as a standard lane with a width of3.5m and a narrow lane with a width of less than 3.5m.The driving simulation experiment is used to simulate such road sections with unequal lane widths,and four road sections with different lane widths and different isolation forms are established,and two scenarios of free flow and parallel flow are set.And taking the lateral distribution,swing and collision risk of the vehicle center position as indicators.The simulation results show that it is feasible to narrow the lane width,the narrow lane has a restraining effect on the vehicle trajectory and has a certain standardizing effect on the driver’s behavior.However,the narrower the lane width and the higher the traffic level,the greater the collision risk.Therefore,for roads with different traffic composition and traffic volume levels,it is necessary to reasonably set the cross-sectional components such as lane width and isolation facilities to maximize the benefits of road functions.