The desire to monitor a section of coastal bluff for slope movements along the North County Transportation District/Amtrak tracks in Del Mar, San Diego County, California led to the development of a continuous monitoring system along approximately 1000 m of track. Because of the length to be monitored, conventional single-point monitoring systems such as multiple tiltmeters or in-place inclinometers (IPIs) were deemed impracticable. Instead, horizontal time domain reflectometry (TDR) coaxial cable sensors were installed along high-concern segments of the track.
