Method of setting maximum speed limit based on minimum generalized running cost of vehicle

Using the idea of multi-objective optimization,a method of setting the maximum speed limit of the vehicle on freeway was proposed considering comprehensively the operation efficiency,safety,economy and comfort.The maximum speed limit under the condition of horizontal and straight road section,free traffic flow,and good pavement and weather was taken as the datum value.A time cost function and a fuel consumption cost function of the vehicle speed on the freeway were established respectively by mathematic modeling and regression analysis.The quantified relationships between the vehicle speed on the freeway and the traffic accident severity as well as the driving comfort were analyzed.Taking minimizing the sum of the time cost and the fuel consumption cost as the objective function and the accident fatality and the comfort that meet corresponding standards as the constraint conditions,a model was built to calculate the datum value of the maximum speed limit based on the minimum generalized running cost of the vehicle.After the calibration of the model parameters,the mathematic method for extremum solution was used to solve the built model,giving out the datum values of the maximum speed limit for the vehicle types on the horizontal and straight road section of the freeway with different design speed.