Determination of load equivalency factors by statistical analysis of weigh-in-motion data

The load equivalency factors for pavement design currently in use by the Hungarian standard have been developed using Weigh-in-Motion data obtained during the first few years of operations after installing some 30 measuring sites in Hungary in 1996. In the past years, and currently, data is collected mainly at the border crossings of the country, however the data is used only for law enforcement purposes, and no comprehensive statistical analyses have been done. To develop actual load equivalency factors for the use in pavement design, data of one year was collected and statistical methods were applied. An algorithm was used to help managing the multimodal distribution of axle loads in mathematical perspectives. Monte-Carlo methods were applied to determine the factors for each heavy vehicle type and eventually for each vehicle class used by the current Hungarian pavement design manual. The calculated factors are considerably different from the current ones, indicating that the pavement design may lead to a false result. Furthermore, there are three vehicle types suggested to be incorporated into the standard due to their high occurrence.

Mechanistic-Empirical Approach to Assessing Relative Pavement Damage

The purpose of this investigation was to examine the feasibility of using conventional pavement analysis tools to derive mechanistic-empirical load equivalency factors (LEFs) applicable to wheel assemblies and pavement cross-sections not included in the AASHTO guide tables in a manner that would provide seamless continuity with current pavement engineering practices. The derivation of such LEFs was pursued on the assumption that two controversial concepts—namely, load equivalency and linear damage accumulation—were, in fact, valid. The purpose of this assumption is to investigate whether it is possible to reach reasonable conclusions for as long as no theoretically valid alternatives to these concepts are available. It was found that it is possible to reproduce with a reasonable fit the statistical/empirical LEFs found in the AASHTO guide tables, using layered elastic analysis and the fatigue relationship derived by Vesic and Saxena. Other conventional fatigue relationships yield unreliable results when compared to the AASHTO LEFs. It is also possible to derive mechanistic-empirical extensions to the AASHTO LEFs using this approach, so tire configurations and pavement cross-sections not included in the AASHTO tables of LEFs can be accommodated in a seamless and equitable manner.