In this paper, we present the design and implementation of a sensor network system for monitoring the flow of traffic through temporary construction work zones. As opposed to long-term work zones which are common on highways, short-term or temporary work zones remain active for a few hours or a few days at most. As such, instrumenting temporary work zones with monitoring equipment similar to those used in long-term work zones is not practical. Yet, these temporary work zones present an important problem in terms of crashes occurring in and around them. Our design for a sensornet-based system for monitoring traffic is (a) inexpensive, (b) rapidly deployable, and (c) requires minimal maintenance. We report on our experiences in building this system, and with testing our system in live work zones in the Cleveland area.