Field suction measurements are especially important for pavements constructed on unsaturated expansive soils. Because these subgrade soils can experience high suction during dry seasons, field sensors that can measure high soil suctions are necessary. In this research, thermal conductivity-based soil suction sensors were evaluated for matric suction measurements at several sites. Laboratory suction measurements with the filter paper method were compared with the field suction measurements with the sensors. Soil water characteristic curves derived from the laboratory and field measurements agreed closely. Volume change measurements using swell and shrinkage tests were conducted separately on the subgrade soils retrieved from the instrumented test sites. The laboratory and field suction data need an adjustment or shift of the time factor to obtain comparable values at high suctions. The influence of total suction on the volumetric swell and shrinkage characteristics of the field subsoils were also addressed.