Research On The Selection Method Of Truck Escape Ramps On Mountainous Expressway

The traffic accidents, made by the heavy-duty truck and due to breaking failure, happen from time to time on the long and steep downgrades of mountainous expressway. At present, the security of a large number of trucks which are out of controlling can be ensured by truck escape ramps(TER). However, still many truck escape ramps can’t play a role on trucks, and even there are casualty accidents happening to drivers and passengers. Therefore, the location of truck escape ramps on the long and steep downgrades are studied in this paper, so as to the function of truck escape ramp can be utmostly exerted, and the safety problem of the mountainous expressway can be improved.The running state and cause of brake failure of trucks on the long and steep downgrades sections were analyzed. The breaking failure is the main reason of truck accidents on the long and steep downgrades. Braking systems on large trucks were analyzed, then 260 ℃ was regarded as the critical temperature of braking efficiency fading. The accident features and accident forms were analyzed, and trucks with 50 t load and Auman six-axis were selected as text models.The commonly location selecting methods of truck escape ramps were analyzed, then the location selecting method which is studied in this paper was put forward. Location affected factors were analyzed, and the cluster analysis method was used to cluster index. Based on clustering results, the evaluation system was established. The centralization statistical method was used to calculate the index weight of truck escape ramps locating model.The temperature rising model of truck drum brake was studied, then it was established. Based on the analysis of energy conversion between the rear drum brake and the external environment, the differential equation of heat rate of the rear drum brake system was established. The number of truck axles was introduced in the differential equation, and the temperature rising model was obtained through solving the differential equation. Through fitting the relationship between drum brake temperature predictive value and measured value, the temperature prediction model of drum brake on long and steep downgrades sections was established.The location selecting model of truck escape ramps was studied. The long and steep downgrades sections were divided into section unit. The security of section unit was divided four levels, respectively, for safety, lower safety, criticality safety and dangerous. The quantification methods of the evaluation index of each section were studied. The section unit was ragared as research object, and the gray related analysis method was used to calculate grey correlation degree between the section unit and security level, then the dangerous section unit was selected to set truck escape ramps.Relying on the Guizhou Ren Chi freeway, the location selecting model of truck escape ramps was applied in the MaGang-HuangJinwan long and steep downgrades. Based on the calculating result, the dangerous section unit was screened out, and the proposed scope of pile of truck escape ramps was determined.