Study On The Geometric Design Indexes Of The Freight-only Interchange Ramps In Passenger And Freight Separation Highway

The proportion of articulated trucks is rising year by year on the highway,passenger and freight mixed traffic is also changing.Because of the difference in body size and dynamic performance between passenger cars and trucks,there are difference in the demand for roads between passenger cars and trucks,in order to reduce the interference of traffic flow and improve the traffic efficiency of roads,the concept of separation of passengers and freight has been proposed.The benefits of some passenger and freight separation highways that have been built in our country have also been proved,but the research on the separation of passenger and freight interchanges is almost blank,and that as a key node of the highway directly affects the efficiency of traffic conversion.The paper takes the freight-only interchange ramps in passenger and freight separation highway as the research object,and studies its geometric design index.This paper collects and reviews relevant domestic and iteratures and uses the US I-95 interstate highway as reference,summarize the definition and basic form of the passenger and freight separation interchange,the classification of traditional vehicle models is not applicable to passenger and freight separation highway,and the classification method of vehicle based on the size of the vehicle body is proposed,and the representative vehicle model and design speeds of the freight-only interchange ramps are determined.Secondly,based on the articulated truck characteristic parameters and the physiological characteristics of the drivers,using the theory of vehicle dynamics and physical mechanics,etc.Research on geometric design indicators for freight-only interchange ramps in general areas and snow-covered areas.Based on the slip rate,the model of stopping sight distance is established,the vehicle turning mathematical model considering the coupling effect for rigid and elastic motions is established,dynamic performance and gradeability model of the vehicle under full load is established,mechanical model of vehicle under synthetic slope is established,ultra-high and lateral force coefficient distribution model and freight-only interchange ramps widening calculation model is established,proposed the proposed values for the geometric design indexes of plane,longitudinal section and cross section of freight-only interchange ramps.Finally,trucksim software was used for simulation,trajectory error,body roll angle,wheel load and lateral acceleration are selected as evaluation indicators to verify the rationality of the design indicator values.The research of the paper provides some theoretical guidances for freight-only interchange ramps in passenger and freight separation highway,and has certain engineering guiding significance for the application of passenger and cargo freight interchange.