Track circuits are used for traffic control on a large portion of North American mainline track. These require insulated rail joints every several kilometers in order to electrically isolate sections of the rail. Such insulated joints have short service lives compared to other track components, but current methods for monitoring their condition and detecting defects are either too involved for everyday use or insufficiently accurate. We are researching a new system based on low-cost smart sensor technology that will enable railroads to monitor the condition of insulated joints, plan for their maintenance or replacement, respond faster to problems, and collect statistical data about their performance. The system uses strain gauges to track the mechanical characteristics of a joint over time. By understanding how these properties change as the joint degrades, we can detect and report problems in a timely manner.