Study On The Length Of Acceleration And Deceleration Lane At Expressway Interchange With Different Vehicle Types

Expressway interchange is the intersection of intersecting road space and interconnecting through ramps to achieve traffic conversion function.Acceleration and deceleration lane is an important part of the interchange system and is area where traffic accident rates are relatively concentrated.Especially when vehicles are driving uphill or decelerating lane downhill,if the length of the lane is insufficient,it will greatly affect the traffic safety of the vehicle.Therefore,the reasonableness of the design of the length of the acceleration and deceleration lane is very important to the safety of the vehicle operation.In order to improve the rationality of the length design of speed change lane and the safety of vehicle operation,this paper analyzes the vehicle traffic characteristics in the merge influence area and diverge influence area and key factors affecting the length of acceleration and deceleration lane.Focus on the length of acceleration and deceleration lane for large and small vehicles.Calculation of the length of direct deceleration lane for large and small vehicles in a single lane: Based on the deceleration theory of vehicles running on deceleration lanes,the deceleration lane length of small vehicle is divided into constant speed section,the first deceleration section(engine braking),the second deceleration section(brake braking).The deceleration lane of large vehicle is divided into constant speed section and deceleration section(brake braking).Establish the deceleration lane length calculation model for large and small vehicles on slopes-2% ?i ?2% and slopes i(27)-2% At the same time,according to the survey data and related regulations,the values of the key parameters in the model are given,calculate the length of the accelerating lane that complies with the vehicle operating conditions in the diverge influence area of the interchange.Finally,the calculation results are compared with the specifications to verify the rationality of the model and parameter selection.Calculation of the length of parallel acceleration lane for large and small vehicles in a single lane: Based on the modified second-order Erlang headway distribution model,establish an acceleration lane length calculation model for accelerating,waiting,and safely entering the main line for large and small vehicles in slopes-2% ?i ?2% and slopes i(27)-2% and the power-to-weight ratios of large vehicles at 8kw/t~12kw/t.At the same time,according to the survey data and related regulations,the values of the key parameters in the model are given,calculate the length of the accelerating lane that complies with the vehicle operating conditions in the merge influence area of the interchange.Finally,the calculation results are compared with the specifications to verify the rationality of the model and parameter selection.