Statewide Statistical Subgrade Characterization

Abstract

This report presents a detailed statistical analysis and graphical presentation of more than 120,000 subgrade modulus values from Minnesota state roads and highways. These subgrade modulus values are based on Falling Weight Deflectometer measurements collected by the Minnesota Department of Transportation between 1983 and 1993. The report gives a one-page summary for each road in each district where measurements exist. This summary page contains a plot of the modulus versus the reference post, modulus versus year when a measurement is collected, modulus histogram, and a number of state-wide summaries. The one-page summaries are accompanied by a number of district and state-wide summaries, and nomograms for the selection of sample spacing, to form the state of Minnesota subgrade modulus Atlas. In addition to this report, a Microsoft Windows-based computer program, the Minnesota Subgrade Modulus Atlas--Online, allows for the detailed analysis of the subgrade modulus along state roads and highways. This analysis can be carried out on a state-wide scale, on a small project scale of less than one mile, or any scale in between. "This electronic form of the Atlas can be easily upgraded as additional measurements become available.