A review of bridge scour monitoring techniques

Isolating the location of scour-induced stiffness loss in bridges using local modal behaviour

“…One study found that 53% of 500 bridge failures occurring between 1989 and 2000 in the United States occurred as a result of flooding and/or scour problems [4]. This issue presents a significant cost burden on bridge owners/managers worldwide between inspections, scour protection installation and repairing damage caused by scour [5]. Scour failures typically occur quite suddenly and generally without prior warning, which can potentially lead to loss of life.…”

“…A range of sensors and methods have been developed to monitor scour hole progression [5]. Simple systems such as Float-Out Devices and Tethered Buried Switches [6,7] float out of the soil when scour reaches their installed depth, triggering a signal.…”

“…Similarly, Ground Penetrating Radar (GPR) can be used to detect scour holes using high frequency electromagnetic waves, which are partially reflected as they pass through different media [3,10]. Sound wave devices such as Sonic Fathometers [5,9,11], Reflection Seismic Profilers [5,10] and Echo Sounders [10] emit sonic pulses to locate the soil-water interface and, hence, the scour depth, using a similar approach to the radar methods. A variety of methods rely on the installation of rods into the soil near a foundation.…”

“…A variety of methods rely on the installation of rods into the soil near a foundation. Magnetic Sliding Collars (MSC) [5,7] involve monitoring the movement of a gravity-controlled sensor which sits on the streambed surrounding a rod. The sensor falls with increasing scour depth relative to the rod and closes magnetic switches along the rod, indicating its depth.…”

Structural Health Monitoring and Design Code compliance for performance assessment of bridges under scour and seismic hazards

“…To 3.3-5 overcome limitations in this assessment process, significant efforts have been made to design remote systems capable of relaying information about scour reducing the need for manual intervention. These systems can be broadly categorized as follows (Prendergast & Gavin 2014): single-use devices (NCHRP 2009;Briaud et al 2011), pulse or radar devices (Forde et al 1999;Yu 2009;Yankielun & Zabilansky 1999), buried or driven rod systems (NCHRP 2009;De Falco & Mele 2002;Zarafshan et al 2012;Fisher et al 2013), sound-wave devices (Nassif et al 2002;Fisher et al 2013;Anderson et al 2007), fiber-Bragg grating devices (Lin et al 2006;May et al 2002) and electrical conductivity devices (Anderson et al 2007). Table 1 gives an overview of the function and detection methodology of a number of types of instrument available.…”