This study aims to further develop and demonstrate the recently-proposed smart rock technology for scour depth and protection effectiveness monitoring. A smart rock is one or two stacked magnets encased in a concrete sphere with a specially-designed rotational mechanism. Design guidelines, rotational mechanisms, remote measurement tools and localization algorithms of smart rocks were developed and validated at three bridge sites. The effect of steel reinforcement in bridge piers/deck on the orientation of gravity-controlled magnets was negligible. The localization accuracy with a single smart rock met a general requirement of less than 0.5 m in engineering applications. The spherical smart rock placed directly on the riverbed of the Roubidoux Creek successfully demonstrated its movement to the bottom of scour hole during the December 27, 2015, flood. Those deployed in the Waddell Creek and the Gasconade River were washed away and thus replaced with smart rocks embedded in deposits such that their top is in flush with the riverbed for improved stability under water current. For rip-rap effectiveness monitoring, polyhedral smart rocks are recommended to increase their interlock with other natural rocks.


Civil, Architectural and Environmental Engineering


United States. Department of Transportation

Keywords and Phrases

Smart Rocks; Scour Depth; Rip-Rap Protection; Magnetic Field; Localization Algorithm

Report Number


Document Type

Technical Report

Document Version

Final Version

File Type





© 2016 Department of Transportation, All rights reserved.

Publication Date

01 Dec 2016