Highways, railways, airport runways and levees (dikes) consist of multiple structural layers which ultimately rest on an earthen subgrade. Over time, erosion, nearby construction, weather, seismic activity and other causes can weaken or create gaps in the lower layers including the subgrade. Initially there is no sign of damage on the surface, until the structure subsides, buckles, or even collapses. This event implies, at a minimum, expenses for immediate repair. It may cause facilities to be shut down, and in the extreme may cause damage to equipment and human fatalities. At present there is no practical way to routinely monitor the condition of the earthen subgrade which supports a road, railway, dike or airport runway.
In this paper we describe a "smart" geofabric which addresses this problem. Our inexpensive Smartroad Tools geofabric can be embedded into or below pavements and other infrastructure during construction or reconstruction. Subsequently, an easy- to-use sensor array can be used to verify the integrity of the subgrade. This process can provide alerts regarding immediate threats to public safety, as well as longitudinal data for optimizing preventive maintenance budgets and activities. This paper describes and presents the results from our second-generation laboratory prototype. We also describe plans for further stages of testing.