Civil Engineering Reference
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11.1.3 Wireless sensor networks: a promising but challenging paradigm
for SHM
Recently, with the rapid advancement of key technologies such as sensors, micro-
processors and wireless networks, wireless sensor network (WSN) has become an
increasingly compelling platform for SHM applications. The most important
property of the WSNs is the inclusion of smart sensor nodes with sensing,
computation, and wireless communication units. Different types of academic or
commercial off-the-shelf smart sensor nodes have been designed or applied to
SHM. These sensor nodes, connected through wireless link, construct aWSN-based
SHM system. Some of the off-the-shelf smart sensor nodes and a typical WSN-
based SHM system deployed on a bridge are shown in Figure 11.1.
Compared with the traditional wire-based SHM systems, WSN-based SHM
systems have significant advantages. Firstly, wireless communication eradicates the
need for wires and, therefore, represents a significant cost reduction and flexibility
over a wire-based counterpart. The price of a smart sensor node is generally much
less than $500. On the contrary, the price per channel for a typical wired-based
system is generally more than $10 000 (e.g., $25 000 on the TsingMa Bridge and
$15 000 on the Bill Emerson Memorial Bridge). The system deployment time is also
dramatically, reduced from months or years for a wired system to days or even
hours for a WSN-based counterpart. Secondly, because of the low cost of each
sensor node, fine grain of monitoring can be achieved, which increases the quality
of assessment. Thirdly, a WSN-based SHM system can use the computational
capability of wireless sensor nodes and realize autonomous and real-time mon-
itoring without aggregating the raw data in the central station.
Despite of the advantages of WSNs listed above, using WSNs in SHM is not as
straightforward as it was in other applications. The difficulties mainly come from
the generally high requirements of SHM applications. Compared with other
applications of WSNs, such as battlefield surveillance, environmental monitoring
Figure 11.1 Off-the-shelf smart sensor nodes and typical deployment of aWSN-based SHM system
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