This Spotlight concentrates on traffic flow sensors, expanding on sensor selection criteria, functioning of the various sensor technologies, providing strengths and limitations of each technology, and summarizing sensor installation and initialization processes as appropriate. It prepares undergraduate and graduate students, civil and transportation engineers, and traffic management professionals, in general, to select and evaluate the accuracy and other performance characteristics of traffic flow sensors for a variety of applications that include signalized intersection control, travel time and speed notification, ramp metering, freeway-to-freeway metering, mainline metering, wrong-way vehicle detection, incident detection, and active transportation and demand management (i.e., active demand management, active traffic management, and active parking management).

The enhanced set includes 24 journal and proceedings papers from the SPIE Digital Library selected by the author that provide additional context and describe a wide variety of applications.