SFO and AMASS
SFO was initially selected for the first test installation of the AMASS ground radar system in 1992. AMASS, which can detect and alert controllers to potential runway conflicts, was intended by the FAA to be eventually installed in 40 airports around the country. However much criticism was directed at the project for cost overruns and lengthy delays. The SFO AMASS was finally declared operational on June 18, 2001. According to AMASS technical support personnel, in a scenario such as this conflict, AMASS is designed to provide an alert 15 seconds before the aircraft reach the conflict point, and the system performed as designed.
Read more about this topic: 2007 San Francisco International Airport Runway Incursion