Ford Motor Company engineers have introduced a host of in-vehicle intelligent active safety technologies that aim to help drivers avoid accidents. The emphasis has expanded from "passive" safety systems (seat belts, airbags and crumple zones), which look to minimize post-crash driver and passenger injury, to include "active" safety systems that focus on pre-collision accident avoidance. Among the first active safety technologies to be successfully shared globally is AdvanceTrac with Roll Stability Control (RSC). The system measures the roll motion of a vehicle and then takes corrective action to help reduce the risk of rollover. The introduction of RSC began with the launch of the Volvo XC90 and was soon migrated onto the Ford Explorer and Ford’s entire North American SUV lineup, according to a spokesman. Another active safety technology, co-developed by Ford R&A and researchers at the Volvo Safety Center, is Collision Warning with Brake Support (CWBS). Launched on the 2007 Volvo S80, CWBS uses forward-looking radar to gauge an impending frontal crash. If a potential collision is detected, a warning is first given via an audio alert and a Head-Up Display light "bar" reflected off of the front windshield. Then, the system augments the driver's braking by automatically applying additional brake pressure to further reduce the vehicle's speed. The Mazda Pre-crash Safety System is another example of a radar sensor mounted toward the front of a car to monitor the vehicle ahead, oncoming vehicles or other obstacles. In addition to a collision warning, if the driver fails to take an evasive action in the event of an impending crash, the vehicle's brakes are applied automatically and the seatbelts are pre-tensioned in an effort to restrain the occupants more effectively. A host of Volvo vehicles are already available with another optional high-tech safety feature, the Blind Spot Information System (BLIS), which utilizes cameras mounted in the side-door mirrors to warn of vehicles in a car's blind spots. Each camera takes 25 pictures every second, while an onboard computer uses these images to determine when another vehicle is alongside. The system then illuminates orange warning lamps positioned near the front-door windshield pillars, providing a subtle warning of a nearby car.