High-speed signalized intersections are associated with vehicle crashes as a result of dilemma zone problems. Dilemma zones are areas in which, at the onset of yellow, some drivers may decide to proceed and some may decide to stop. This disagreement between drivers can lead to rear-end crashes or right-angle crashes. The research objective of this work was to conduct a field comparison of a radar-based dilemma zone protection system with high-resolution data. Researchers compared the frequency of red light runners and percentage of arrivals in green. In addition, researchers desired to shed more light on the value of using high-resolution data in such a comparison and how much data would be needed. Researchers found that 1 week of high-resolution data is sufficient to draw conclusions on the effectiveness of a radar-based dilemma zone protection system. A before-and-after comparison of red light running frequency indicated a reduction of up to 80% in red light running when a radar-based dilemma zone protection system was used.