Nowadays sensor networks are employed in a huge amount of applications such as human tracking, safety structures monitoring or intelligent transportation systems. The first chapter of the book is focused on an overview of sensor networks and their main applications within Intelligent Transportation System. Moreover, the chapter includes a brief description of the SAFESPOT European project, co-funded by the European Community. The second chapter presents two sensor network applications, the first one regards a monitoring system applied to the Olympic pedestrian cable-stayed bridge of Torino. The second network is a risk mitigation proposal for building sites. The third chapter presents a flexible, robust, low-cost and low-maintenance sensor node solution for vehicle detection. In the fourth chapter, outdoor and indoor experimental tests are proposed and, in particular, the results obtained by road measure campaigns are presented. The best sensor node compromise between power consumption and processing performance are evaluated. The more appropriate version of embedded detection algorithm is pointed out. Finally, a brief description of future work is discussed.