A monitoring system for an electric vehicle that draws current from a conductor is provided. The monitoring system includes a plurality of sensor modules distributed at spaced intervals throughout a conducting block of a current collector. The conducting block contacts the conductor in operation of the vehicle. Each sensor module comprises a strain sensor configured to output a first optical signal that reflects changes in strain and temperature of the conducting block and a strain-isolated temperature sensor that is configured to output a second optical signal that reflects changes in temperature of the conducting block. The monitoring system also includes an optical source for illuminating each sensor module and an optical signal interpretation module configured to receive first and second optical signals from each said sensor module. The optical signal interpretation module is configured to determine, from the optical signals, a temperature-independent strain measurement for each said sensor module.