Nissan Motor Co. says it is the first automaker to have a new safety system working on its vehicles that links its cars with roadside sensors to warn drivers of dangerous intersections and blind spots. The goal is to reduce traffic accidents and congestion. Originally 1,000 roadside sensors were planned for Japan, but recent budget cuts scaled back implementation to 15 sites. Using sensors posted on poles around high-risk intersections, cars approaching the intersection are monitored and information is sent to the car’s navigation computer. Collision risk is calculated, and drivers are warned as needed.