Abstract. Since 2008, a sensor network on a major Dutch highway bridge has been monitoring the structural health of the bridge, by measuring various parameters at different locations along the infrastructure. These parameters include strain, vibration and climate. The aim of the InfraWatch project is to model the health and behavior of the bridge by analyzing the large quantities of data that the sensors produce. One of the many forms of modeling involved is the identification of traffic events (cars, trucks, congestion and so on), as knowing when they occur, and of what nature they are, will enable modeling the response of the bridge to each of these events. In this paper, we approach the problem as a time series subsequence clustering problem. As it is known that such a clustering method can be problematic on certain types of time series, we verified known problems on the InfraWatch data. Indeed some of the undesired phenomena occurred in our case, but to a lesser extent than previously suggested. We introduce a new distance measure over subsequences that discourages the observed behavior and allows us to identify traffic events reliably, even on large quantities of data.