Detailed crash analyses indicate that poor gap selection, rather than stop sign violation, is the primary causal factor in crashes at rural, unsignalized intersections. To determine under what conditions the gap selection process fails, a transportable rural intersection surveillance system has been designed and implemented. The system can be installed at any rural intersection, and can be used to collect data regarding the gap acceptance behavior of drivers at the rural intersection. Described herein is the design and performance of the transportable rural intersection surveillance system. This system will be deployed at eight rural intersections in eight US states, from April 2006 through December 2008. Data collected by the system will be used to determine whether regional differences in gap acceptance behavior exist. If differences exist, they will be quantified and used in the design of an Intersection Decision Support system, a device under development designed to assist a driver at a rural intersection with the gap selection process.