Determining the moisture content of pavement structures for seasonal variations has long been a key concern for pavement designers. Until now, estimates or "best guess" moisture levels provided the basis for design parameters. Today, through the use of Time Domain Reflectometry, moisture content can be calculated accurately and inexpensively.

This document provides information to pavement engineers on Time Domain RefIectometry, a technique that indirectly measures the in situ volumettic moisture content of soil. It describes the technique and presents a model for predicting moisture content.