  This paper presents the state-of-the-art on Collision Avoidance and Collision
Warning (CA,CW) systems. Traffic accidents result from driver errors or
situations that are unpredictable for the driver. CA,CW systems are developed
for reducing traffic accidents and saving peoples lives by warning drivers or
taking compensatory action when drivers can not react fast enough. Besides
these initiatives, this paper explains the importance of CA,CW driving
assistance systems by considering economic issues as well. Technological
developments are investigated in the context of finished and ongoing projects
all over the world. CA,CW system algorithms are discussed regarding performance
criteria such as reliability and strictness. This paper also presents the
information on Inter-Vehicle Communication Systems (IVC) which will be a key
ingredient of future CA,CW systems.
