Route monitoring system and method

A monitoring system comprising:

• a transmit monitor configured to be disposed onboard a first vehicle system moving along a route, the transmit monitor including one or more first processors configured to control injection of a transmitted current into one or more conductive components of the route;
• and
• a receive monitor configured to be disposed off-board the first vehicle system, the receive monitor including one or more second processors configured to measure a received current that represents at least a portion of the transmitted current that is conducted through the one or more conductive components of the route, wherein the transmitted current and the received current are injected and received, respectively, at different spaced-apart locations along the one or more conductive components of the route while the transmit monitor moves relative to the receive monitor;
• wherein the receive monitor is configured to generate sampled values of the measured received current by sampling the measured received current at plural different points in time during which plural vehicle systems that include the first vehicle system travel over the route plural times;
• and
• wherein the receive monitor is configured to examine changes in the sampled values to identify a contaminated portion of a surface on which the one or more conductive components of the route are disposed.