This report contains information concerning:

  1. The statistical determination of frequencies of critical axle loadings on highway bridges and
  2. The adaptability and adaptability of historical loadometer and classification data in Kentucky to the recently adopted AASHO design criteria for evaluating the fatigue history of existing bridges.

The analysis of the fatigue history of a bridge consists of evaluating the distribution of instantaneous axle loadings over the applicable period. Because of the urgency, only historical records currently available were used as source data. This report is therefore divided into two sections: 1) a summary of quantitative results based on available data, and 2) recommendations for future studies. The purposes of the first part of this report are:

  1. To delineate a methodology for statistically predicting the distribution of vehicle loadings with respect to, time and
  2. To develop the history of critical loadings, based on existing traffic data, for each of the twenty-one highway bridges crossing the Ohio River from Kentucky.

The purposes of the second part of the report are:

  1. To describe the types of information required in these analyses and to propose data collection procedures which will provide source data for future analysis and
  2. To recommend further study of certain design criteria.

Report Date


Report Number

No. 251

Digital Object Identifier



The opinions, findings, and conclusions in this report are not necessarily those of the Department of Highways or the Bureau of Public Roads.