The US civil infrastructure is aging and has been identified by several institutions (e.g. US-DOT, FHWA, FTA) as an area in critical need of improvement. ASCE estimates that current deterioration trends can have disastrous consequences in terms of costs ($520 billion by year 2040), and socioeconomic impact (loss of ~ 400,000 jobs nationwide) [1].  Approximately 25% of bridges in the US were identified as structurally deficient or functionally obsolete in 2009 [2]. Most of these structures are typical bridges, consisting of a concrete deck supported by steel girders (stringers). It becomes evident that sustainable preservation of existing infrastructure represents a goal that is essential for future vitality of the US economy and the prosperity of the US society, and the need is growing every day. With an aging infrastructure it becomes crucial to make informed decisions about maintenance and preservation actions, and renewal. Structural Health Monitoring (SHM) can be an important aid in this decision process. In spite of its great potential, however, SHM is not applied in a widespread or generic manner, mainly due to the lack of reliable and affordable monitoring solutions. Thus, there is a demand for monitoring methods that are not specific to individual structures, are reliable and robust on-site, and applicable to typical bridges.