A Study On Evaluation Method Of Expressway Pavement Roughness Based On Riding Comfort Theory

The expressway is a highway designed for high-speed travelling on which bothdirections are separated, and whose entrances and exits are fixed. Bearing specificfunctions, the pavement quality or performance of the expressway draws a lot ofattention. Pavement roughness is a key indicator to show riding quality and ridingcomfort, even more a necessary condition to realize the safety, fast, comfort, andeconomical function of an expressway. Thus it’s essential to understand and evaluatethe expressway pavement roughness precisely.With analyzing7years pavement quality or performance data comes from7different expressways in Beijing, the study discusses several issues in the process ofevaluating pavement roughness based on relevant theories. From the aspect of spatialcharacteristic, the study analyzes how the pavement roughness influences the ridingcomfort. Take the rutting for example, after studying the relation between damage outof shape and pavement roughness, the study put forward a new method to evaluate thepavement deformation based on riding quality. The study concludes that the differentevaluating unit length values can influence the accuracy of international roughnessindex. The smaller the evaluating unit length value is, the more precise informationcan be observed from the data, which offers us a reference for experiment designingand data analyzing.Based on previous conclusions, an experiment is implemented on10differentsections of expressways in Beijing. From the aspect of passenger riding comfort, theexperiment use ECG data and vibration acceleration value to evaluate the ridingcomfort. During the experiment, Multi-function Laser Road Condition Test Vehicle,Electrocardiogram Tester, Vibration acceleration Tester and stopwatches are adoptedto collect the real-time values of driving speed, International Roughness Index, ECGdata and acceleration data at different mileages. After preliminary analysis,1000meters and20meters are selected as length of evaluation unit. From the aspect of thewhole and parts, the study evaluates the riding comfort on the base of asphalt roadpavement roughness.Through data analyzing, the linear regression equation describing the relationamong weighted acceleration root mean square value, pavement roughness value andspeed is established. And then the quantitative relation between total weightedacceleration root mean square and road age is put forward on the base of current researching. Moreover the study argues the necessity of decreasing the length ofevaluation unit when evaluating pavement roughness of a specific section of anexpressway. The study also concludes the quantitative relation between the addition tomean heart rate and various influence factor when there is a sudden fluctuation inpavement roughness.Stepping into the time of large-scale maintenance, when the human-orientedsafety concept is getting more and more attention, the conclusion drawn from thestudy can be used to life cycle maintenance cost analysis, and it is proved to be a moreeconomical, humanity and comprehensive method to management and decisionmaking in highway maintenance while keeping a reasonable riding comfort.