V. CONCLUSION
This paper has reviewed the range of WSNs used for condition
monitoring in the railway industry. The emphasis is on
the practical engineering solutions, principally which sensors
devices are used and what they are used for; and, identification
of sensor node configurations and network topologies.
Until recently, railway inspection has been visually performed
[70], but this only examines objects superficially and
intermittently, and the analysis needs to be interpreted by an
expert, who can be subjective. Sensors are objective and can
provide data from the entire object (including internally) to
allow the whole object’s health to be fully assessed and to
analyze its durability and remaining life time. A broad range of
sensors are used in railway monitoring to provide an extensive
range of data and allow monitoring of different structures,
vehicles and machinery. The main challenge for WSNs in
railway applications is determining the best measurement technologies
to use. The WSN must be reliable and accurate to
enable effective condition monitoring in harsh and inaccessible
environments but must also be cost effective. It must be possible
to translate the sensor data from the WSN into relevant and
clear information to enable decision support in the railway
infrastructure maintenance lifecycle.