Study On The Grade And Length Of Interchange Ramp

Interchange is an indispensable part of the expressway,with the rapid development ofexpressway,highway construction will be focus on the mountainous areas,and the number ofinterchanges in mountainous area will continue to increase.When designing the interchangeramp and toll station,engineer often use bigger grade in order to overcome the elevationdifference,avoid adverse terrain,as well as control the size and cost of construction.But thecurrent road design specifications doesn’t have detailed regulations and instructions forpractical application,and the study on the grade of the ramp and toll stations didn’t go deepeither.In practice, the designer select the value of grade and length more casual,this leads tomany unreasonable ramp of vertical alignment and the road can not meet the demand for roadcapacity and driving safety.Therefore,the research on the grade and length of ramp should besolved urgently.Based on a large collection of relevant information and literature,this article study thegrade and length of the ramp and toll stations.By analyzing the vehicle speed and roadcapacity influence by grade and length of the ramp and calculating the vehicle dynamicperformance,this article raise values of design parameters on grade and length of the rampuphill according to different large vehicle rate to guarantee the minimum allowable speed ofmain vehicle on the ramp,then,by calculate the power fator of main vehicle on the snowroad,according to the friction coefficient,this article give the maximum grade of interchangerampin the snow and ice area.On the basis of calculating and analyzing the final speed of themain vehicle on the downhill ramp and the braking performance of main vehicle, this articleraise values of design parameters on longitudinal and length of the ramp downhill and tollstation to ensure the safety as a goal.Research conclusion provides theory basis for correcting existing specifications on gradeand length of ramp and toll station of interchanges.It has a certain practical significance.